A new deep-sea crustacean family of Tanaidacea is established from Aotearoa New Zealand and Southeast Australia based principally on morphology

Family Arthruridae n. fam

LSID urn: lsid: zoobank.org:act:1C11F461-89D8-4721-9B78-81E78F3EE4FA

Diagnosis

Cuticle well calcified, ornamented and often shiny, white, and brittle. Carapace flask-shaped or domed-capsule (“egg-shaped,”⁵); eyelobes absent or reduced, optical elements absent; rostrum shallow but acute. Pereonites lateral margins with supracoxal projections, more rarely smoothly convex; pereonite-1 weakly trapezoidal [narrower posteriad], with or without hyposphenium. Pleon narrower than pereon and pleotelson, or about equal; pleonites well-defined or slightly obscure; epimeral setation sparse, with setae at least on pleonite-5. Pleotelson pentagonal [“agathotanaoid”] or sub-cupiliform [cf. “cupiliform”⁷). Antennule four-articled; article-1 without distomesial seta; article-2 weakly overlapping article-3, shorter than articles 3–4 combined. Antenna six-articled; article-2 longer/larger than article-3, with dorsodistal seta, with or without distolateral seta; article-3 with dorsodistal seta; article-4 without fusion line. Mandible molar cylindrical, apex coronal or palmate/sub-coronal, with > five terminal spines and/or tubercles. Maxillule endite with seven or eight terminal spines, at least one bifid or pectinate. Maxilliped bases together chordate or cuneate, with weak medial ridge proximally setose, or naked; endites not fused, with two distal low-rounded tubercles [‘gustatory cusps’²⁴) and one or two setae. Epignath with large terminal seta. Cheliped with posterodorsal attachment to cephalothorax, via large sclerite extending to posterior of carapace; basis with posterior lobe; chela fixed finger with two ventral setae, incisive margin without proximal diastema and process; dactylus dorsal margin smooth, ventral margin without proximal process, with/without peglike spines. Pereopods 1–6 sticklike. Pereopods 1–3 merus shorter than carpus and propodus, with one inferodistal spine; carpus very slender (> 3 L: W), with three slender distal spines and one or more setae; pereopod-1 propodus with two inferodistal spines (one mesial and weaker). Pereopods 4–6 ischium with two short setae, rarely one; merus slender (> 1.5 L: W); carpus slender (> 2 L: W) with three slender distal spines and one seta; propodus with superior plumose sensory seta (PSS) [pereopods 4–5 only] and one or two (pereopod-6) slender superodistal spines. Pleopods absent in female; present in non-swimming males, straplike, in tent-like configuration; rami without proximal setae. Uropod exopod fused with peduncle, well-developed, oblique from or proximate to endopod; endopods bisegmented, or unisegmented, axial to peduncle, not forcipate.

Type genus

Arthrura Kudinova-Pasternak, 1966⁵.

Other genera

Libanius Lang, 1971¹¹, Arthruropsis n. gen., Paralibanius n. gen.

Etymology

From first-described genus Arthrura.

Invariant-implicit characters

Carapace usually with small seta adjacent to eyelobes. Pereonites all shorter than broad, at most equal. Antenna article-1 naked. Labium outer lobes much reduced or absent. Labrum truncate in dorsal or ventral view, hood-like, distally setose. Maxilliped endites subrectangular, weakly flared, each with setulate distolateral corner; palp article-1 without setae; article-2 with lateral seta and three mesial setae, simple and variously pinnate/pectinate; article-3 with four mesial setae (two small, two large) except A. bombus (three setae); article-4 with one subdistal and five terminal setae. Cheliped smooth, without crenulation or nodules; sidepiece naked; merus with one ventral seta; carpus with two ventral setae, usually with single proximo- and dorsodistal setae; palm with near-parallel dorsal and ventral margins, and distolateral spine near dactylus attachment; fixed finger with three setae on lateral incisive margin; dactylus with proximomesial spine. Pereopods 1–3 coxa annular, with distal seta; ischium with one short seta. Pereopod-1 carpus setae short; claw L similar to pereopods 2–3. Pereopods 4–6 merus with two slender inferodistal spines; propodus with two inferodistal spines and short acuminate process above dactylus attachment. Uropod extending beyond pleotelson.

Remarks

The nine Arthrura-like morphospecies from NZ and SE Australian waters form part of this family-level taxon that can be distinguished from the tanaellids. As mentioned above, Tanaellidae is a precariously defined family with considerable morphological diversity and the genus Arthrura is a clear outlier in this respect (Fig. 1). In the recent account of the new family Caudalongidae Błażewicz and Bird, 2024⁸ based on both morphological and molecular methods analysed with Bayesian inference and RaxML maximum likelihood analysis, four undescribed Arthrura species formed a clade excluding several Tanaella species, with robust statistical support indicated by a bootstrap value of 0.76 and posterior probability of 1 in the Bayesian analysis In that study, the phylogenetic value of the cheliped sclerite was emphasised. Arthrurids have a relatively large version that extends to the posterior margin of the carapace, which contrasts with that of core tanaellids (such as Tanaella) where it is usually narrower and often partly obscured (Fig. 4; Błażewicz et al. 2024⁸: Fig. 5A; Table 2). Arthruridae n. fam. also shares more characters with Agathotanaidae (e.g. the genera Paragathotanais Lang, 1971²⁵ and Paranarthrura) such as the pleon-pleopod-pleotelson configuration mentioned previously (apomorphic relative to tanaellids? ), and generally ’sticklike‘ pereopods (plesiomorphic? ). It retains what might be inferred as a more plesiomorphic mandible morphology (a non-reflexed and complex molar) and an anaxial cheliped-cephalothorax articulation (the cheliped basis with a free posterior lobe; ‘proximalen Vorsprunge’¹¹). Other paratanaoideans have a similar pseudo-agathotanaid combination of characters, such as the caudalongids: Caudalonga Larsen, 2005²⁶, Facultatotanais Błażewicz and Bird, 2024⁸, Macrinella Lang, 1971¹¹, Pseudoarthrura Larsen, 2005²⁶, and Universitatotanais Błażewicz and Jakiel, 2024⁸, but with an unfused, or at least only partly fused uropod exopod, and smaller, dorsally located sclerite (Błażewicz et al. 2024: Fig. 6A; Table 2)⁸. The shape of the cheliped palm is also distinct from many tanaellids, particularly those of Tanaella and Araphura, with sub-parallel dorsal and ventral margins, a form seen widely in other paratanoidean families such as Leptocheliidae Lang, 1973²⁷, Paratanaidae Lang, 1949²⁸, Pseudotanaidae Sieg, 1976²⁹, and Typhlotanaidae Sieg, 1984³⁰. A more distally flared palm is expressed in the Akanthophoreidae Sieg, 1986¹⁵ and Tanaellidae (see above).

A notable diagnostic character of the Arthruridae is the large maxilliped epignath with a prominent distal seta (Fig. 2C); in a few preserved specimens this can be seen protruding from the posterior dorsolateral branchial openings on the cephalothorax (e.g. Figure 22A). This was emphasised as a unique character among the Paratanaidae [sic.] by Lang (1971¹¹: 389) in his description of the genus Libanius. It now serves as a family diagnostic.

Along with this level of morphological distinctiveness from other families is variation within the existing and novel species that can be hypothesised as genus-level clusters. The new family, Arthruridae, is here established to hold four genera (two new) and 13 species (one a new combination, nine new). Although the type species Arthrura andriashevi (and now the type genus) is relatively poorly described, and the holotype consists only of an appendage-less body (and no cephalothorax), the decision to use the name is pragmatic should future studies synonymise any of the newly-described or restored genera (such as Libanius) with Arthrura.

• Arthrura Kudinova-Pasternak, 1966.

• Arthrura Kudinova-Pasternak, 1966.—Kudinova-Pasternak (1973)³¹: 162, non Arthrura s.s. (= Armatognathia Kudinova-Pasternak, 1987³²).

• Libanius Lang, 1971.—Sieg and Zibrowius (1988)¹²: 193.

• Paranarthrura Hansen, 1913.—Vanhöffen (1914)¹³, as Paranarthrura monacanthus.

Diagnosis

Adapted from Kudinova-Pasternak⁵. Arthrurid with cephalothorax < 20% BL [except Paralibanius n. gen., see below). Pereonites with supracoxal projections; with hyposphenium on pereonite-1. Pleon narrower than pereon and pleotelson; pleonites distinct. Pleotelson pentagonal. Antennule intermediate relative to cephalothorax L [≈ 0.75 L: W]; article-1 slender [> 3 L: W]. Antenna article-2 shorter than broad, only slighter longer than article-3, dorsal margin simple; article-3 dorsal seta shorter than article; article-5 intermediate L [2.7 L: W]. Mandible molar coronal, with blunt and sharp tubercles. Maxillule endite with two bifid spines. Maxilliped bases without medial setulate process. Cheliped carpus dorsal margins spinulate. Pereopod-1 thin sticklike [≈ 15 L: W] overall. Pereopod-1 (at least) basis with setulate superior margin; merus inferodistal spine long [= article L); propodus with distolateral slender spine (superodistal seta overlooked? ). Pereopods 2–3 carpus with one distal seta. Pereopods 4–6 claw clearly longer [> 1.2×] than propodus. Uropod longer than pleotelson; peduncle simple; endopod bisegmented, L:W intermediate [3–5 L: W]; exopod divergent from endopod.

Type species

Arthrura andriashevi Kudinova-Pasternak, 1966⁵, by original designation.

Geographic range

North Pacific, East Pacific.

Bathymetric range

Abyssal, 4000–6085 m.

Remarks

This type species remains enigmatic and not fully-described, yet it usually falls into its own clade in iterations of morphological phylogenetic analyses by a combination of characters that exclude the apparent synapomorphy of a spinulate margin on the cheliped carpus. The synonymy of Libanius is not definitive and here Arthrura andriashevi is retained as the only species in the genus. In her description of A. andriashevi, Kudinova-Pasternak referred to both specimens as ‘females without oostegites’ although the larger is certainly a male, having pleopods. In arthrurids, females lack pleopods and these only start to develop in juvenile males, as in agathotanaids such as Paranarthrura. They were usefully illustrated and described for A. monacantha¹⁵. Vanhöffen’s specimen (p.479, Fig. 16a)¹³ is that of a juvenile male.

Arthrura andriashevi does not appear to have been recorded since its original discovery from two sites ≈ 3700 km apart: the Emperor Trough (North Pacific) at 6065 m depth, and the Sukuku Basin, SE of Japan, at 4000–4150 m (Kudinova-Pasternak 1966)⁵. Neither specimen was designated as a holotype, so the type locality of A. andriashevi is unresolved. This wide distribution, both geographic and bathymetric, appears unlikely but this could be resolved with the recovery of Arthrura-like species from these areas.

Another species, Libanius longicephalus Kudinova-Pasternak, 1978³³, currently listed under the genus Arthrura⁸, has an articulated uropod exopod, excluding it from the Arthruridae. It is insufficiently described but the holotype (and only specimen) may be a juvenile male with undeveloped pleopods. However, the characteristic minute distal article on the exopod uropod (Fig. 6)³³ is similar to that observed in Leptognathioides biarticulata Bird, 2014³⁴ and Portaratrum holdichi Bird, 2014³⁴, but as Kudinova-Pasternak made no mention of a spur on the sternum of pleonite-5, we consider Libanius longicephalus a congener of the former genus, as Leptognathioides longicephalus n. comb.

• Arthruropsis n. gen.

• LSID urn: lsid: zoobank.org:act:058460C1-2AEC-400E-AE74-AC3BA9B90C0A

• Arhaphuroides.—Larsen (2005)²⁶: 232–239, in part [for A. bombus].

Diagnosis

Arthrurid with pereonites 1–6 lateral margins with supracoxal projections; pereonite-1 without hyposphenium. Pleon as wide as pereon and pleotelson; pleonites distinct. Pleotelson sub-cupiliform. Antennule long relative to cephalothorax [≈ 0.8×]; article-1 not slender [≈ 2.8 L: W]. Antenna article-2 slightly longer than broad, with dorsodistal apophysis; article-3 dorsal seta longer than article; article-5 fairly slender [3.7 L: W]. Mandible molar coronal, with low tubercles and longer spines. Maxillule endite with two coarsely pectinate (“multifurcate”²⁶) spines. Maxilliped bases without medial setulate process. Cheliped basis posterior lobe reaching pereonite-1; carpus dorsal margin smooth. Pereopods 1–6 basis smooth. Pereopod-1 thin sticklike [≈ 15 L: W overall]; merus inferodistal spine long [= article L]; propodus with inferodistal spine and distolateral seta (superodistal seta overlooked? ). Pereopods 2–3 carpus with one distal seta. Pereopods 4–6 thin, sticklike [≈ 11 L: W]; claw slightly longer [< 1.2×] than propodus. Uropod slightly longer than pleotelson; peduncle simple; endopod unisegmented (or weakly bisegmented), L:W intermediate [4 L: W]; exopod proximate to endopod.

Type species

Arthruropsis bombus (Larsen, 2005)²⁶ n. comb.

Etymology

A combination of the genus nomen Arthrura and the Greek suffix ὄψις ‘opsis,’ suggesting affinity or likeness. Gender masculine.

Geographic range

Gulf of Mexico, Northwest Atlantic.

Bathymetric range

Bathyal, 658–677 m.

Remarks

Among the arthrurids, Arthruropsisis principally characterised by the wide pleon, a near-cupiliform (or at least non-agathotanaoid) pleotelson (Fig. 69²⁶), an apparent lack of pleonal setation, relatively long antennule, the antennal article-2 with a dorsodistal apophysis, and weakly segmented (or unisegmented) uropod endopod.

Geographic separation and apparent isolation of Arthruropsis bombus from other arthrurids support evidence from morphology that is a distinct taxon from Arthrura, and Arhaphuroides bombus is now placed in this new genus. The genus Arhaphuroides belongs in Tanaellidae sensu stricto and can be difficult to distinguish from Araphura and is probably polyphyletic (Bird unpublished work).

Diagnosis

Arthrurid with cephalothorax ≥ 20% BL. Pereonites with strong or weak supracoxal projections; pereonite-1 with or without hyposphenium. Pleon narrower than pereon and pleotelson; pleonites distinct or indistinct. Pleotelson pentagonal. Antennule not long relative to cephalothorax [< 0.8×] (except L. concertator n. sp., see below); article-1 fairly stout to slender [2–3.5 L: W]. Antenna article-2 longer than broad, dorsal margin simple; article-3 dorsal seta longer than article or not; article-5 fairly slender or slender [> 2.5 L: W]. Mandible molar coronal or subpalmate, with low tubercles and longer spines. Maxilliped bases usually with medial setulate process. Cheliped basis posterior lobe just short of, or reaching, pereonite-1; carpus dorsal margin smooth. Pereopods 1–6 basis smooth. Pereopod-1 thin, sticklike [> 12.5 L: W] overall; merus inferodistal spine intermediate or long [> distal width; = article L]; carpus with one or two distal setae; propodus with inferodistal spine and distolateral seta [except one species, see below]. Pereopods 2–3 carpus with one or two distal setae; propodus with inferodistal spine. Pereopods 4–6 stout to very thin sticklike [9.2–14.4 L: W]; claw slightly shorter to longer [< 1.2×] than propodus. Uropod shorter to longer than pleotelson; peduncle simple or arcuate/geniculate; endopod bisegmented, L:W usually stout or intermediate [< 5 L: W]; exopod divergent or proximate to endopod.

Type species

Libanius pulcher Lang, 1971¹¹, by original designation.

Other species

Libanius australis n. sp., Libanius brevicarpus n. sp., Libanius clisicola n. sp., Libanius concertator n. sp.; Libanius intonsus n. sp.; Libanius largitas n. sp.; Libanius monacanthus; Libanius projectus n. sp.; Libanius tangaroa n. sp.

Geographic range

Eastern Central Pacific, Subantarctic Southern Ocean, Southwest Pacific.

Bathymetric range

Bathyal–abyssal, 204–4052 m.

Remarks

The genus as defined here remains heterogenous at the scale of relatively minor or subtle morphological differences with more obvious variant characters being the presence/absence of a hyposphenium on pereonite-1, the length of the uropod exopod (shortest in L. pulcher), and presence/absence of setules on the basis of pereopods 1–3. It is distinguishable from Arthrura by the lack of spinules on the dorsal margin of the cheliped carpus, and longer cephalothorax (proportional to body length), and from Paralibanius n. gen. by the more posterior attachment of the chelipeds on the cephalothorax.

• Libanius australis n. sp.

• LSID urn: lsid: zoobank.org:act:F799BCA8-902F-4B38-BDF2-113BA3F25C87

• (Figs. 1, 3 and 5–7)

Type material

HOLOTYPE: non-ov. ♀, 5.5 mm, J.57786, SLOPE Stn 32. PARATYPES: 1 manca-3, 2 non-ov. ♀♀, 1 posterior frag. (non-ov. ♀) (most decalcified), J.57867, 1 non-ov. ♀ dissected on microslides, J.57,785, 1 ♂, ICUL.13160 (ex. J.57867), SLOPE Stn 32; 2 non-ov. ♀♀ (one in 2 pieces), 1 ov. ♀, J.57849, SLOPE Stn 33; 1 manca-2 in 2 pieces, 1 non-ov. ♀? (damaged anterior frag.), 1 juvenile (juv.) ♂, 1 ♂ (small), J.57850, SLOPE Stn 33; 1 manca-2, 10 non-ov. ♀♀, 1 anterior fragment (non-ov. ♀?), 1 juv. ♂, 1 ♂, J.39274, 1 ♂, ICUL13161 (ex. J.39273/4), SLOPE Stn 40; small non-ov. ♀ (decalcified), J.57898, SLOPE Stn 40; small non-ov. ♀ (decalcified), J.62707, SLOPE Stn 45; 1 non-ov. ♀ (decalcified), J.37859, SLOPE Stn 46.

Type locality

Tasman Sea, South of Point Hicks, Victoria, Australia, 1000 m.

Etymology

From the Latin adjective australis for ‘southern’, alluding to the Australian locality.

Diagnosis

Libanius with cephalothorax longer than pereonites 1–2 combined. Pereonite-1 L: W intermediate [0.33 L: W], without hyposphenium; pereonite-6 not long [0.6 L: W]. Pleon just shorter than broad, pleonites distinct. Pleotelson L: W intermediate [≈ 0.7×], 0.8× pleon L. Antennule L intermediate relative to cephalothorax [≈ 0.7×]. Antenna article-2 2× article-3 L, distodorsal setae very short; article-4 fairly slender [4.1 L: W]. Mandible molar broad coronal. Maxillule endite with two coarsely pectinate spines. Cheliped basis not reaching posterior of cephalothorax; basis much longer [≈ 1.6×] than merus; merus slightly longer [1.4×] than that of carpus ventral margin; chela L: W intermediate [≈ 2.3 L: W], slightly narrower than carpus, palm dorsal and ventral margins about parallel, with 5-spined mesial comb. Pereopods 1–3 basis without groups of setules. Pereopod-1 merus inferodistal spine as long as article; carpus L: W intermediate [3.7 L: W]. Pereopod-2 carpus with one distal seta. Pereopods 4–6 overall thin [≈ 11 L: W]; merus stout [1.5 L: W], much shorter than carpus [≈ 0.5×]; carpus slender [3.6 L: W]; claw ≈ propodus L. Uropod slightly shorter than pleotelson [≈ 0.8×]; peduncle simple; endopod L: W intermediate [3.5 L: W]; exopod L: W intermediate [2.9 L: W], proximate to endopod.

Description

Holotype non-ovigerous female: Habitus Fig. 5 A–B) fairly slender, 7 L: W. Cephalothorax ≈ 1.25 L: W, 23% BL, L reaching half of pereonite-3. Pereon slightly tapering posteriad, pereonites 2–6 with convex lateral margins, pereonites 4–6 with more distinct process over pereopod attachment, 0.33, 0.53, 0.65, 0.81, 0.94, and 0.6 L: W, respectively. Pleon parallel-sided, 0.9 L: W, 11.5% BL; pleonites naked (but see male with epimeral setae). Pleotelson slightly longer than pleonites 2–5 combined), 0.73 L: W, posterior weakly-produced, with two simple dorsoposterior setae.

Paratype non-ovigerous female: Antennule Fig. 6 A) 3.6 L: W overall; article-1 0.55× L of whole, 2 L: W, with two groups of three lateral PSS, and long distolateral seta (on holotype); article-2 ≈ 0.29× article-1 L, ≈ 0.9 L: W, not overlapping article-3 dorsally, with two distolateral seta, and distomesial seta; article-3 shorter than broad, with single distolateral (long) and distomesial (shorter) setae and one PSS; article-4 slender, 3 L: W, with five setae and one aesthetasc. Antenna Fig. 6B) ≈ 0.85× antennule L; article-1 shorter than broad; article-2 1.2 L: W, dorsum slightly raised, with dorsodistal seta half as long as article-3, and with distoventral seta; article-3 shorter than broad, with longer dorsodistal seta; article-4 longer than articles 1–3 CL, with two long and one short distal setae, and three PSS; article-5 3.8 L: W, 0.37× article-4 L, with distal seta; article-6 small, with five setae.

Mouthparts: Labrum Fig. 6 C) typical of genus, hood-like, distally setulate. Mandibles Fig. 6D–E) with left incisor with about six cusps, lacinia as long as incisory, subconical, molar broad, apex with blunt tubercles and array of about eight acuminate spines; right incisor tricuspid, molar as for left mandible. Labium Fig. 6 F) medial lobes longer than broad, subtriangular, with apical setules. Maxillule Fig. 6G) endite with sparse distal setules, apex with eight spines of various thickness. Maxilla not observed.

Maxilliped Fig. 6 H) bases together chordate, 1.5 L: W, partly extending over endites, with median setulate ridge, with seta near articulation with palps; endites typical, mesial tubercles broad and shallow, and two distal setae; palp ≈ 0.9× basis L, article-1 as long as broad, article-2 sub-triangular, as long as broad, setation typical; article-3 subrectangular, as long as article-2, 1.5 L: W, setation typical; article-4 slender, subrectangular, shorter than article-3, 3.3 L: W, setation typical. Epignath Fig. 6I), typical, as long as maxilliped.

Cheliped Fig. 7 A) robust; bases as long as broad, posterior lobe shorter and lower than anterior mass; merus simple; carpus narrower distally, 1.5 L: W, with round posterior lobe, setation typical; chela 1.3× carpus L, palm 1.1 L: W; fixed finger 0.8× palm L.

Pereopod-1 Fig. 7B) slender, almost 15 L: W overall; coxa annular, with seta; basis slender, 6.5 L: W, with proximal superior PSS; merus 1.8 L: W; carpus subrectangular, ≈ 1.7× merus L, spines typical, superodistal spine over half propodus L, with one distal seta; propodus narrower and just shorter than carpus, 4.5 L: W, with superodistal seta and inferodistal spine and seta; dactylus with accessory seta, unguis twice as long as dactylus, together ≈ 0.9× propodus L. Pereopod-2 Fig. 7 C) similar to pereopod-1 but basis with superior seta and PSS; propodus without inferodistal seta. Pereopod-3 Fig. 7D) similar to pereopod-2 but basis merus and carpus slightly shorter.

Pereopod-4 Fig. 7E) basis slender, 4.5 L: W, with one inferior PSS; merus stout; carpus slender, subrectangular, 1.9× merus L; propodus slender, as long as carpus, 4.4 L: W, inferior margin with row of small spinules; dactylus longer than unguis. Pereopod-5 Fig. 7 F) similar to pereopod-4 but basis with two superior and two inferior PSS. Pereopod-6 Fig. 7G) similar to pereopod–5 but basis naked; propodus setation typical.

Uropod Fig. 7 H) peduncle fairly slender, 2 L: W; endopod 1.2× peduncle L, segment-1 longer than segment-2, with two large distomesial PSS, segment-2 with one subdistal seta, four apical setae and one PSS; exopod strong, arcuate, reaching distal of segment-1 of endopod.

Maleabitus (Fig. 5C–D) similar to non-ovigerous female but with stouter antennules and pleopods with setae; BL 2–2.2 mm.

Distribution

Recorded from the southwestern Tasman Sea off Gippsland, Victoria, and eastern Tasmania.

Bathymetric range

Bathyal, 400–1000 m.

Remark

In the second phylogenetic analysis (Fig. 3) L. australis is shown as a sister to Libanius clisicola n. sp. (see below) among the clade of three Australian species, but it differs in its shorter pereonite-1 and pleon, stouter antennule article-1, pereopod-1 merus and propodus, proportionally shorter pereopod-4 merus relatively to the carpus, and more slender uropod peduncle. It appears to have no synapomorphy to distinguish it from all other species of Libanius.

• Libanius brevicarpus n. sp.

• LSID urn: lsid: zoobank.org:act:0945FDAC-0253-485A-8BE0-8AC515499349

• (Figs. 1, 3 and 8–9, 37 C)

Type material

HOLOTYPE: non-ov. ♀, 2.7 mm, J.71186, SLOPE Stn 1. PARATYPE: 1 ♂, dissected on microslides, ICUL.13177 [ex.J.57819], SLOPE Stn 1.

Type locality

Tasman Sea, off Nowra, NSW, Australia, 204 m.

Etymology

From the Latin brevis ‘short’ and the pereopod article carpus, alluding to the short carpus on each of pereopods 4–6.

Diagnosis

Libanius with cephalothorax longer than pereonites 1–2 combined. Pereonite-1 short [0.33 L: W], without hyposphenium; pereonite-6 long [0.7 L: W]. Pleon as long as broad, pleonites distinct. Pleotelson L: W intermediate [0.8×], 0.9× pleon L. Antennule L intermediate relative to cephalothorax [0.75×]. Antenna article-2 much longer [1.8×] than article-3, distodorsal setae short; article-4 fairly slender [5.6 L: W]. Mandible molar broad coronal. Cheliped basis not reaching posterior of cephalothorax; basis much longer [1.5×] than merus; merus much longer [2.5×] than that of carpus ventral margin; chela L: W intermediate [≈ 2.4 L: W], slightly narrower than carpus, palm dorsal and ventral margins parallel. Pereopods 1–3 basis without groups of setules. Pereopod-1 merus inferodistal spine as long as article; carpus fairly stout [3.4 L: W]; propodus with one inferodistal spine, without distolateral seta Pereopod-2 carpus with two distal setae. Pereopods 4–6 overall thin [≈ 9.2 L: W]; merus L: W intermediate [2 L: W], shorter than carpus [≈ 0.7×]; carpus stout [2.1 L: W]; claw ≈ propodus L. Uropod as long as pleotelson; peduncle simple; endopod L: W intermediate [4.25 L: W]; exopod slender [≈ 4 L: W], proximate to endopod.

Description

Holotype non-ovigerous female: Habitus Fig. 8 A–B) fairly stout, 5.4 L: W. Cephalothorax Fig. 37 C) ≈ 1.1 L: W, 23% BL, L reaching half of pereonite-3. Pereon slightly tapering posteriad, pereonites 2–6 with distinct process over pereopod attachments, ≈ 0.33, 0.56, 0.57, 0.77, 0.79, and 0.7 L: W respectively. Pleon parallel-sided, as long as broad, 11% BL; pleonites naked. Pleotelson typical of genus.

Male paratype: Antennule Fig. 8 C) ≈ 0.75× cephalothorax L (holotype female), stouter than in female, 3.7 L: W overall; article-1 0.44× L of whole, 1.6 L: W, with distolateral group of three lateral PSS, and long distolateral seta; article-2 ≈ 0.4× article-1 L, ≈ 0.7 L: W, not overlapping article-3 dorsally, with distolateral seta and four PSS; article-3 shorter than broad, with single distolateral and distomesial setae; article-4 slender, with incipient division, 2.5 L: W, with five setae, one aesthetasc and one PSS. Antenna Fig. 8D) ≈ 0.7× antennule L; article-1 shorter than broad; article-2 1.1 L: W, dorsum slightly raised, with short dorsodistal and distoventral setae; article-3 shorter than broad, with longer dorsodistal seta; article-4 longer than articles 1–3 CL, with two long setae and two PSS; article-5 3.3 L: W, 0.26× article-4 L, with distal seta; article-6 small, with five setae.

Mouthparts (paratype): Labrum Fig. 8E) typical. Mandibles Fig. 8 F–G) with left incisor and lacinia not recovered, molar broad, apex with blunt tubercles and array of about eight acuminate spines and comb of thinner spines; right incisor five-cuspid, molar as for left mandible. Labium, maxillule and maxilla not observed.

Maxilliped Fig. 8 H) bases together chordate, 1.5 L: W, partly extending over endites, with median setulate ridge, with seta near articulation with palps; endites typical, mesial tubercles broad and shallow, and two distal setae; palp ≈ 0.9× basis L, article-1 as long as broad, article-2 sub-triangular, as long as broad, setation typical; article-3 subrectangular, as long as article-2, 1.5 L: W, setation typical; article-4 slender, subrectangular, shorter than article-3, 2.6 L: W, setation typical. Epignath not recovered.

Cheliped Fig. 9 A, 37 C) robust; bases as long as broad, posterior lobe not much smaller than anterior mass; merus long; carpus narrower distally, 1.7 L: W, with round posterior lobe, setation typical; chela 1.1× carpus L, palm as long as broad, mesial comb not observed; fixed finger 1.2× palm L; dactylus with about three peglike spines on incisive margin.

Pereopod-1 Fig. 9B) very slender, 13.5 L: W overall; coxa annular, with seta; basis slender, 6.25 L: W, with two proximal superior PSS; merus 2.4 L: W; carpus subrectangular, ≈ 1.4× merus L, spines typical, superodistal spine ≈ 0.5× propodus L, with two distal setae; propodus narrower and longer than carpus, 5.8 L: W, with small superodistal seta, and inferodistal spine and seta; dactylus with accessory seta, unguis 1.4× dactylus L, together ≈ propodus L. Pereopod-2 Fig. 9 C) similar to pereopod-1 but carpus with two distal setae and PSS; propodus without superodistal seta (probably lost on figured specimen). Pereopod-3 Fig. 9D) similar to pereopod-2 but basis without PSS; propodus with superodistal seta.

Pereopod-4 Fig. 9E) basis slender, 4.3 L: W, with one inferior PSS; merus not slender, carpus slender, setation typical; propodus slender, longer than carpus, 5.8 L: W, setation typical, (thinner superodistal spine missing? ), inferior margin with row of small spinules, small acute apophysis above dactylus insertion; claw broken – see pereopod-5. Pereopod-5 Fig. 9 F) similar to pereopod-4 but basis with two inferior PSS; dactylus longer than unguis, together as long as propodus. Pereopod-6 Fig. 9G) similar to pereopod–5 but basis with superior PSS; propodus setation typical.

Pleopod Fig. 9 H) typical; both rami straplike, endopod slightly shorter than exopod with subdistal seta and five terminal setae, exopod with seven distal setae.

Uropod Fig. 9I) peduncle fairly slender, 1.7 L: W; endopod 1.4× peduncle L, segment-1 longer than segment-2, naked (PSS possibly lost/broken), segment-2 with one subdistal seta, four apical setae and two PSS; exopod strong, not arcuate, reaching beyond distal of segment-1 of endopod.

Distribution

Recorded only from the type locality.

Bathymetric range

Shallow bathyal, 204 m.

Remarks

Without a pereonite-1 hyposphenium or setose pereopod bases, L. brevicarpus n. sp. is distinguished from similar Libanius species by its relatively long pereonite-6 and stout pereopod-4 carpus. Compared to the other two Australian species it also differs in having a slightly longer antennule article-1 and antenna article-2, the cheliped slightly more anterior on the ventrum of the cephalothorax, and a more slender uropod exopod.

This species has the shallowest bathymetric record of all the arthrurids ̶ just shallower than those for the NZ species L. tangaroa n. sp. (see below).

• Libanius clisicola n. sp.

• LSID urn: lsid: zoobank.org:act:4AAC3036-1EB4-409B-8348-A0D9458C08F1

• (Figs. 1, 3 and 10–13)

Type material

HOLOTYPE: juv. ♂, 5 mm, J.37884, SLOPE Stn 15. PARATYPES: 2 manca-3 (decalcified), J.57830, 1 non-ov. ♀, 5.6 mm, dissected on microslides, ICUL.13223 (ex.J.57830), 1 juv. ♂, J.71187, SLOPE Stn 25.

Type locality

Tasman Sea, off Nowra, NSW, Australia, 1750 m.

Etymology

From the Greek klísi κλίση ‘gradient’ (or ‘inclination’, etc.) and Latin suffix -cola ‘dweller’, alluding both to the bathymetric zone and the project SLOPE itself.

Diagnosis

Libanius with cephalothorax as long as pereonites 1–3 combined. Pereonite-1 L: W intermediate [≈ 0.44 L: W], with hyposphenium. Pleon longer than broad [1.2 L: W], pleonites distinct. Pleotelson almost as long as broad. Antennule L intermediate relative to cephalothorax [≈ 0.65×]. Antenna article-2 slightly longer [1.25×] than article-3, distodorsal setae very short; article-4 fairly slender [4.9 L: W]. Mandible molar broad coronal. Maxillule endite with one coarsely pectinate spine. Cheliped basis reaching posterior of cephalothorax; basis much longer [≈ 1.6×] than merus; merus slightly longer [1.4×] than that of carpus ventral margin; chela L: W intermediate [≈ 2.4 L: W], slightly narrower than carpus, palm dorsal and ventral margins clearly divergent, with 4-spined mesial comb. Pereopods 1–3 basis with groups of setules. Pereopod-1 merus inferodistal spine shorter than article; carpus fairly stout [3.5 L: W]. Pereopod-2 carpus without setae. Pereopods 4–6 overall thin [≈ 10.5 L: W]; merus stout [1.7 L: W], shorter than carpus [≈ 0.65×]; carpus slender [3.25 L: W]; claw ≈ propodus L. Uropod shorter than pleotelson [≈ 0.6×]; peduncle simple; endopod stout [2.7 L: W]; exopod L: W intermediate [2.3 L: W], proximate to endopod.

Description

Paratype non-ovigerous female: Habitus Fig. 10 A–B) fairly stout, 5.1 L: W. Cephalothorax ≈ 1.3 L: W, 25% BL. Pereon slightly tapering posteriad, pereonites 2–6 with convex lateral margins, 0.44, 0.57, 0.78, 0.76, 1.0, and 0.64 L: W respectively. Pleon parallel-sided, 10% BL; pleonites 1 and 5 slightly longer than rest; pleonite-5 with two dorsolateral setae. Pleotelson slightly longer than pleonites 3–5 combined (holotype), almost as long as broad, posterior weakly-produced, with two simple dorsoposterior setae.

Antennule Fig. 11 A) ≈ 0.65× cephalothorax L (holotype), 4.5 L: W overall; article-1 0.55× L of whole, 2.45 L: W, with two groups of three lateral PSS, and long distolateral seta; article-2 ≈ 0.35x article-1 L, ≈ 1.1 L: W, weakly overlapping article-3 dorsally, with distolateral seta and one PSS; article-3 shorter than broad, with single distolateral (long) and distomesial (shorter) setae and one PSS; article-4 slender, 2.9 L: W, with five setae and one aesthetasc. Antenna Fig. 11B) ≈ 0.8× antennule L; article-1 shorter than broad; article-2 1.25 L: W, distally wider, dorsum slightly raised, with scattered microtrichia; article-3 as long as broad, with longer dorsodistal seta; article-4 longer than articles 1–3 CL, 4.9 L: W, with one long and one short distal setae; article-5 3.25 L: W, 0.33× article-4 L, with distal seta; article-6 small, with four setae.

Mouthparts (paratype): LabrumFig. 11C) typical. Mandibles Fig. 11D–E) with left incisor distally wider, with about six cusps, lacinia as long as incisory, subconical, molar broad, apex with blunt tubercles and array of about eight acuminate spines; right incisor with several cusps, molar as for left mandible. Labium Fig. 11 F) medial lobes longer than broad, subtriangular, with apical setules. Maxillule Fig. 11G) endite with sparse distal setules, apex with eight spines of various thickness. Maxilla Fig. 11 H) subovate.

Maxilliped Fig. 11 H) basal pedestal broader than bases, bases together cuneate (or deltoid), 1.5 L: W, partly extending over endites, with weak, naked median ridge, and seta near articulation with palps; endites typical, mesial tubercles broad and shallow, and two distal setae. Palp ≈ 0.8× basis L, article-1 as long as broad; article-2 sub-triangular, as long as broad, setation typical; article-3 subrectangular, as long as article-2, 1.5 L: W, setation typical; article-4 slender, subrectangular, shorter than article-3, 3.3 L: W, setation typical. Epignath Fig. 11I), typical, as long as maxilliped.

Cheliped Fig. 12 A) robust; bases as long as broad, posterior lobe shorter and lower than anterior mass, latter with small dorsolateral seta; merus simple; carpus narrower distally, 1.5 L: W, with round posterior lobe, setation typical; chela 1.3× carpus L, palm 1.2 L: W; fixed finger ≈ palm L; dactylus with ventral margin with two peglike spines.

Pereopod-1 Fig. 12B) very slender, 15 L: W overall; coxa annular, with seta; basis slender, 6.8 L: W, with proximal superior seta and groups of setules along superior margin; merus ≈ 2.2 L: W; carpus elongate, subrectangular, ≈ 1.5x merus L, spines typical, superodistal spine ≈ 0.5× propodus L, with two small distal setae; propodus narrower and just shorter than carpus, 5.5 L: W, with superodistal seta, and inferodistal spine and seta, inferior margin with spinules; dactylus with accessory seta, unguis twice as long as dactylus, together ≈ 1.2× propodus L. Pereopod-2 Fig. 12 C) similar to pereopod-1 but basis, merus, carpus and propodus (4.7 L: W) very slightly shorter; propodus with one inferodistal spine. Pereopod-3 Fig. 12D) similar to pereopod-2 but basis very slightly shorter.

Pereopod-4 Fig. 12E) basis slender and as long as those of pereopods 1–2, 4.4 L: W, with one inferior and one superior PSS; merus stout; carpus slender, subrectangular; propodus slender, slightly longer than carpus, 5.5 L: W, setation typical, inferior margin with row of small spinules; dactylus longer than unguis, with inferior spinules. Pereopod-5 Fig. 14 F) similar to pereopod-4. Pereopod-6 Fig. 12G) similar to pereopod–5 but basis with inferior PSS in proximal position; propodus setation typical.

Uropod Fig. 12 H) fairly stout, 1.2 L: W; endopod 1.5× peduncle L, segment-1 slightly longer than segment-2, with two large distomesial PSS, segment-2 with four apical setae and two PSS; exopod strong, arcuate, reaching about half length of endopod (distal of segment-1), with one subdistal and two distal setae (one broken on figured specimen).

Juvenile male: Habitus Fig. 10 C–D, 13) similar to non-ovigerous female; BL holotype 5 mm, paratype J.71187, 4 mm. Carapace with seta posterior to antennule (possibly lost on holotype). Pleon epimera with seta (possibly lost on holotype). Antennule stouter, 4 L: W. Pleopods present but rudimentary, naked.

Distribution

Recorded from the southwestern Tasman Sea off Nowra (NSW) to off Gippsland (Victoria).

Bathymetric range

Bathyal, 1500–1850 m.

Remarks

Overall, L. clisicola n. sp. most closely resembles L. australis, but it has the most elongate pleotelson of all Libanius species, a relatively slender pleon (longer than broad), a very short distodorsal seta on antenna article-2, and small groups of setae on the bases of pereopods 1–3.

• Libanius concertator n. sp.

• LSID urn: lsid: zoobank.org:act:08C901A5-2312-44BB-8067-DAB5124B8A46

• (Figs. 1, 3 and 14–16, 32 A–B; 36 A)

Type material

HOLOTYPE: non-ov. ♀, 3.03/3.88 mm, NIWA 173617, TAN0707 Stn 119, 40.5305°S 178.5136°W, 533 m, epibenthic sled, 13 November 2011. PARATYPES: non-ov. ♀, NIWA 133401, NZOI Stn Q689; juv. ♂, NIWA 173619, TAN0707 Stn 105; 1 manca-3, NIWA 173620, 3 non-ov. ♀♀, 1 ov. ♀, NIWA 42,934, 1 non-ov. ♀ dissected on 2 microslides and remains in ethanol, NIWA 173621, TAN0707 Stn 119.

Other material

2 non-ov. ♀♀, NIWA 173618, TAN0705 Stn 136; 1 non-ov. ♀, NIWA 173622, TAN1004, Stn 27.

Type locality

Challenger Plateau, Tasman Sea, Southwest Pacific, 533 m.

Etymology

From the Latin noun concertator, a “contender (or challenger)”; referring to the type locality, itself named for the HMS Challenger, a Pearl Class screw corvette that was used for the historic British oceanographic cruise of December 1872 to May 1876³⁶.

Diagnosis

Libanius with cephalothorax slightly longer than pereonites 1–2 combined. Pereonite-1 relatively long [≈ 0.5 L: W], without hyposphenium; pereonite-6 not long [0.56 L: W]. Pleon about as long as broad, pleonites weakly defined. Pleotelson short [0.6 L: W], ≈ 0.7× pleon L. Antennule long relative to cephalothorax [≈ 0.8×]. Antenna article-2 1.4× article-3 L, distodorsal seta shorter than article-3; article-4 slender [8.3 L: W]. Mandible molar broad coronal. Maxillule endite with one coarsely pectinate (trifid? ) spine. Cheliped basis not quite reaching posterior of cephalothorax; basis longer [2.5×] than merus; merus longer [1.6×] than ventral margin of carpus; chela L: W intermediate [2.4 L: W], slightly narrower than carpus, palm dorsal and ventral margins clearly divergent, with 3-spined mesial comb. Pereopods 1–6 basis without groups of setules. Pereopod-1 merus inferodistal spine L longer than article; carpus very slender [5.6 L: W]. Pereopod-2 carpus with one distal seta. Pereopods 4–6 overall very thin [13.6 L: W]; merus slender [2.6 L: W], shorter than carpus [0.7×]; claw longer [1.4×] than propodus. Uropod longer [1.3×] than pleotelson; peduncle geniculate; endopod slender [≈ 6.5 L: W], longer than peduncle; exopod fairly slender [≈ 3.5 L: W], proximate to endopod.

Description

Holotype non-ovigerous female: Habitus Fig. 14 A) fairly stout, 5.7 L: W. Cephalothorax ≈ 1.2 L: W, 21% BL, slightly longer than pereonites 1–2 (excluding interpereonal; gaps) combined; carapace with small seta adjacent to eyelobes. Pereon slightly tapering posteriad, 0.5, 0.64, 0.61, 0.68, 0.65, and 0.58 L: W respectively; each with anterolateral seta, pereonites 4–6 also with posterolateral seta. Pleon parallel-sided, 10% BL; pleonites 1 and 5 slightly longer than rest. Pleotelson Fig. 14B) slightly longer than pleonites 3–5 combined (holotype), posterior weakly-produced, with two simple setae and two PSS, with one seta anteroventral to uropod insertion, with small conical apex with four setae (ventral-most pair deflexed); anterolateral anal ridges not meeting medially, gap between these and pleonite-5 less than 25% of pleotelson L.

Antennule Fig. 14 C) 5.6 L: W overall; article-1 0.6× L of whole, 3.4 L: W, with three lateral PSS, distolateral seta and three PSS; article-2 ≈ 0.3× article-1 L, ≈ 1.6 L: W, not overlapping article-3 dorsally, with distolateral seta, smaller distomesial seta, and three PSS; article-3 as long as broad, with single distolateral (long) and distomesial (shorter) setae; article-4 slender, 3.3 L: W, with one thin seta, four long setae, and one aesthetasc closely applied one of the setae (fused? ). Antenna Fig. 14D) ≈ 0.75× antennule L; article-1 shorter than broad; article-2 1.25 L: W, distally wider, dorsum slightly raised; article-3 as long as broad, with longer dorsodistal seta; article-4 1.3× articles 1–3 CL, with one long and two short distal setae, and four distal PSS; article-5 slender [5 L: W], as long as article-2, with distal seta; article-6 small, with five setae, two possibly fused.

Mouthparts (paratype): Labrum (not figured) typical. Mandibles Fig. 15 A–B) with left incisor narrow and weakly crenate, lacinia as long as incisory, subconical (?), molar broad, apex with about four blunt tubercles and array of about seven acuminate spines; right incisor weakly tricuspid, molar as for left mandible. Labium Fig. 15 C) medial lobes longer than broad, subtriangular, with apical setules. Maxillule Fig. 15D) endite with sparse distal setules, apex with seven spines of various thickness, one strongly pectinate. Maxilla not recovered.

Maxilliped Fig. 15E–F) basal pedestal broader than bases, bases together 1.6 L: W, median ridge with apical setules; endites typical; palp ≈ 0.9× basis L, article-1 as long as broad; article-2 sub-triangular, as long as broad, setation typical, one mesial seta stouter and more pectinate than others; article-3 subrectangular, as long as article-2, 1.6 L: W, setation typical; article-4 slender, subrectangular, shorter than article-3, 3.3 L: W, setation typical, with longitudinal fringe of setules. Epignath Fig. 15G), typical, as long as maxilliped.

Cheliped Fig. 15 H–I) robust; bases fully occluding cephalothorax ventrum, partly separated by anteriad-produced sternal apophysis; basis as long as broad, as long as merus, posterior lobe shorter than anterior mass, latter with small dorsolateral seta; merus long; carpus narrower distally, 1.7 L: W, with round posterior lobe; chela 1.2× carpus L, palm as long as broad; fixed finger ≈ 1.5× palm L; dactylus incisive margin with two peglike spines and distal co-axial spine.

Pereopod-1 Fig. 16 A) slightly more slender (1.3×) than pereopod-4; basis slender, 7.6 L: W, with proximal superior seta and PSS; merus ≈ 3 L: W, inferodistal spine longer than merus; carpus elongate, subrectangular, ≈ 1.4× merus L, superodistal spine almost as long as propodus; propodus narrower and just shorter than carpus, 5.5 L: W, distolateral spine thinner than inferodistal spine inferior margin with spinules, and setules near dactylus insertion; unguis clearly longer than dactylus [1.5×], together with dactylus ≈ 0.9× propodus L. Pereopod-2 Fig. 16B) similar to pereopod-1 but basis, merus, carpus and propodus (4.6 L: W) very slightly shorter. Pereopod-3 Fig. 16 C) similar to pereopod-2 but basis very slightly shorter, without superodistal seta.

Pereopod-4 Fig. 16D) basis slender and as long as those of pereopods 1–2, 6.3 L: W, with one inferior PSS; merus slender; carpus slender, subrectangular, 1.2× merus L, 4 L: W; propodus slender, as long as carpus, 4.8 L: W, inferior margin with row of small spinules; dactylus longer than unguis, with two rows of spinules. Pereopod-5 Fig. 16E) similar to pereopod-4 but basis with two inferior and one superior PSS. Pereopod-6 Fig. 16 F) similar to pereopods–5 but basis without inferior PSS; propodus setation typical.

Uropod Fig. 14E) projecting beyond pleotelson; peduncle slender (2.5 L: W); endopod weakly bi-segmented, 1.4× peduncle L, segment-1 slightly longer than segment-2, with two large distomesial PSS, segment-2 with one subdistal seta, three long, one small thin, terminal setae and one terminal PSS; exopod strong, acute, proximate to endopod, reaching about half length of endopod (distal of segment-1), with single long subdistal and distal setae.

Manca-3: BL 1.67 mm. Pereopod-6 rudimentary. Pleopods absent.

Non-ovigerous female: As holotype, BL 2.6–3.9 mm (n = 9), 5.5–5.7 L:W.

Ovigerous female: Similar to non-ovigerous female but with oostegites. Pleon 7% BL; BL 2.9 mm.

Juvenile male: Habitus (Fig. 32A) similar to non-ovigerous female; BL 2.12–2.39 mm (allotype BL 2.12 mm). Antennule stouter, 4.5 L:W. Pleopods (Fig. 32B) present but rudimentary, naked.

Distribution

Recorded from the Challenger Plateau, west of New Zealand, the northern flank of the Chatham Rise, and the Hikurangi Margin.

Bathymetric range

Shallow bathyal, 532–1013 m.

Remarks

One of five species of Libanius from NZ waters, L. concertator n. sp. shares with L. largitas n. sp. (see below) a weak definition of the pleonites in most specimens, the relatively long antennule article-1, antennule article-2 only slightly shorter than articles 3–4 combined, the cheliped slightly anterior on the cephalothorax ventrum, and the pereopods 4–6 claw longer than the propodus. For differences between these morphometrically similar species (Table 2) see remarks for L. largitas n. sp.

Of 12 post-mancae specimens only one is a (juvenile) male, i.e. a relatively high sex ratio of 1: 11 males to females. Eight specimens were in a single sample, from TAN0707 Stn 119, at 533 m on the Challenger Plateau, west of Te Ika-a-Māui North Island.

• Libanius intonsus n. sp.

• LSID urn: lsid: zoobank.org:act:BC26B891-F091-4BA2-B334-CCBF64A24771

• Ocean Census species 45.

• (Figs. 1, 3 and 17–21, 32 C–D, 36B)

Type material

HOLOTYPE: non-ov. ♀, 5.0 mm, NIWA 13950, NZOI Stn S152. PARATYPES: 2 non ov. ♀♀, 1 ♂, NIWA 12829, 20 non-ov. ♀♀ [1 dissected on 4 microslides, NIWA 173623], 1 ov. ♀, 1 juv. ♂, 1 ♂, NIWA 173629, NZOI Stn S152; 1 manca-2, 1 non-ov. ♀, 1 juv. ♂, NIWA 173624, TAN2402, Stn 47.

Other material

3 non ov. ♀♀, 1 ov. ♀, NIWA 14197, NZOI Stn S150; 14 non ov. ♀♀, 2 juv. ♂♂, 3 ♂♂, NIWA 12811, 1 non-ov. ♀, NIWA 14010, NZOI Stn S151; 1 non-ov. ♀, 3 juv. ♂♂, NIWA 80855, TAN0705 Stn 48; 1 manca-3, NIWA 173625, TAN1006 Stn K8; 1 non-ov. ♀, NIWA 173626, TAN1501 Stn Caravel; 1 manca-3, NIWA 173627, TAN1904, Stn 62; 1 manca-3, NIWA 173628, TAN1904, Stn 70.

Type locality

45.8717°S 171.0817°E, Chatham Rise (southern flank), NZEEZ, Southwest Pacific, 1676 m.

Etymology

From the Latin adjective intonsus, “unshaved,” alluding to the sparsely setulate pereopods 1–3.

Diagnosis

Libanius with cephalothorax ≈ pereonites 1–3 CL. Pereonite-1 short [< 0.4 L: W]; pereonite-1 without hyposphenium; pereonite-6 not long [0.65 L: W]. Pleon as long as broad, pleonites well defined. Pleotelson not stout [≈ 0.75 L: W, ≈ 0.8× pleon L]. Antennule short relative to cephalothorax [≈ 0.6×]. Antenna article-2 1.5× article-3 L, distodorsal seta about half article-3 L; article-4 L: W fairly slender [≈ 5 L: W]. Mandible molar broad coronal. Maxillule endite with one coarsely pectinate spine. Cheliped basis reaching posterior of cephalothorax; basis slightly longer [1.2×] than merus; merus much longer [2.7×] than ventral margin of carpus; chela slender [≈ 2.6 L: W], clearly narrower [0.75×] than sub-parallel, palm with 4-spined mesial comb. Pereopods 1–3 basis, carpus, and ventral margins with groups of setules. Pereopod-1 merus inferodistal spine shorter than article; carpus fairly stout [≈ 3.6 L: W]. Pereopod-2 carpus with two distal setae. Pereopods 4–6 overall very thin [12 L: W]; merus stout [≈ 1.6 L: W], much shorter than carpus [< 0.6×]; claw ≈ propodus L. Uropod shorter than pleotelson [0.75×]; peduncle geniculate; endopod L: W intermediate [≈ 3.4 L: W], longer than peduncle; exopod stout [≈ 1.8 L: W], proximate to endopod.

Description

Holotype non-ovigerous female: Habitus Fig. 17 A, 36B) fairly stout, 4.8 L: W. Cephalothorax 1.05 L: W, 23% of BL. Pereon slightly tapering posteriad, 55% of BL; pereonites with weak convex lateral margins, pereonites 4–6 with weak lateral process over coxal attachments, 0.35, 0.57, 0.68, 0.81, 0.87, and 0.65 L: W respectively; each with anterolateral seta. Pleon slightly tapering posteriad, as long as broad, 11.5% of BL, pleonites 1 and 5 slightly longer than the others; pleonites, tergites and sternites distinct, epimera with seta, that of pleonite-5 long. Pleotelson Fig. 17B) as long as pleonites 2–5 combined, 10% of BL; posterior weakly produced, with two simple setae and two PSS, with one seta anterior to uropod attachment; apex conical with four setae, ventral-most longer and more deflexed; anterolateral anal ridges meeting medially, gap between these and pleonite-5 ≈ 30% of pleotelson L.

Paratype non-ovigerous female, 5.3 mm, NIWA 173623: Antennule Fig. 17 C) 4.6 L: W; article-1 ≈ 0.55× of TL (total length), 2.5 L: W, with proximomesial setules, three lateral PSS, distolateral seta and two or three PSS; article-2 0.33× article-1 L, ≈ 1.1 L: W, with distolateral seta and three PSS, and small distomesial seta; article-3 shorter than broad, with single distolateral (long) and distomesial (shorter) setae, and one distolateral PSS; article-4 slender, 3.7 L: W, with three thin setae, three long setae, and one aesthetasc closely applied to one of the setae (fused? ). Antenna Fig. 17D) ≈ 0.8× antennule L; article-1 shorter than broad; article-2 ≈ 1.3 L: W, dorsal margin raised (convex), with dorsodistal seta, and distolateral seta; article-3 smaller than article-2, slightly wider than broad, with dorsodistal seta about as long as article; article-4 1.2× articles 1–3 combined length (CL), with two long and two short distal setae, and one (?) distal PSS; article-5 shorter than article-2, 3 L: W, with distal seta; article-6 small, with six setae.

Mouthparts (paratype): Labrum Fig. 18 A) typical. Mandibles Fig. 18B–D) body with rugose outer margin; left incisor distally broad in full profile, crenulate, lacinia as long as incisor, subrectangular, weakly tricuspid, molar broad, larger than incisor, with apex bearing at least six small subterminal tubercles; right incisor three-cusped, molar similar to that of left mandible. Labium Fig. 18E) typical, medial lobes longer than broad, subtriangular, with apical setules. Maxillule Fig. 18 F) endite with distal setules, apex with eight spines of various thickness. Maxilla Fig. 18G, 21B) laminate, almost as large as maxilliped endite.

Maxilliped Fig. 19 A, 21 A) basal pedestal broader than bases, bases together cuneate, 1.7 L: W, median ridge with proximal setules; endites typical; palp ≈ 0.8× basis L, article-1 as long as broad; article-2 sub-triangular, as long as broad, setation typical; article-3 subrectangular, narrower than article-2, twice as long as broad, setation typical; article-4 slender, subrectangular, shorter than article-3, 3 L: W, setation typical. Epignath Fig. 19B) typical, as long as maxilliped, with large pectinate distal seta.

Cheliped Fig. 19 C) robust; basis 0.9 L: W, left and right occluding ventrum of cephalothorax, posterior lobe slightly longer than anterior mass, latter with small dorsolateral seta; merus ventral margin long; carpus slightly narrower distally, 1.7 L: W; chela 1.2× carpus L, 2.6 L: W, palm 1.3 L: W; fixed finger slightly shorter than palm, incisive margin with two widely-spaced low teeth, and larger distal weakly bifid tooth; dactylus incisive margin apparently smooth.

Pereopod-1 Fig. 20 A, 21B) overall very thin, 20 L: W; basis very slender, 9.0 L: W, with proximal superior seta, and sparsely distributed setules (or naked); merus 1.8 L: W; carpus elongate, subrectangular, 1.7× merus L, spines typical, with two distomesial setae; propodus narrower but 1.1× carpus L, 6.0 L: W, with superodistal seta and two unequal distolateral and inferodistal spines, mesial inferior margin with row of spinules, and setule comb near dactylus insertion; unguis 1.8× longer than dactylus, together as long as propodus. Pereopod-2 Fig. 20B) similar to pereopod-1 but 17 L: W overall; basis stouter 7.7 L: W, with proximal superior seta and PSS; merus shorter and slightly stouter, 1.7 L: W; carpus shorter and slightly stouter, 3 L: W, spines typica; claw just shorter than propodus. Pereopod-3 Fig. 20 C) similar to pereopod-2 but slightly shorter, 15.5 L: W overall; basis and merus each slightly shorter and stouter, 6.9× and 1.5 L: W respectively, basis with simple seta only; carpus, propodus and claw similar, but carpus with one superodistal seta.

Pereopod-4 Fig. 20D) 12 L: W overall; basis slender and as long as that of pereopod-1, slightly wider, 5.7 L: W, with two inferior PSS; merus stout; carpus slender, subrectangular, 1.7× merus L, 3.2 L: W; propodus slender, slightly longer than carpus, 5.7 L: W, setation typical, with inferior margin with double row of small spinules; dactylus longer than unguis, pectinate. Pereopod-5 Fig. 20E) as pereopod-4, but basis stouter, 4.2 L: W; carpus slightly shorter; claw as long as propodus. Pereopod-6 Fig. 20 F) similar to pereopod–5 but basis naked (PSS not observed) and slightly more slender, 5.7 L: W; merus smaller, 1.8 L: W; propodus slightly shorter and more slender, 5.9 L: W, setation typical.

Uropod Fig. 17E) peduncle 1.7 L: W; endopod 1.4× peduncle L, segment-2 shorter than segment-1, segment-1 with two large distomesial PSS, segment-2 with one subdistal seta, one small and three long terminal setae, and one terminal PSS; exopod strong, arcuate, proximate to or weakly divergent from endopod, reaching half endopod L but short of endopod segment-1 distal, with single long subdistal and distal setae.

Manca-2: BL 2.2 mm (n = 1). Pereonite-6 very short and pereopods-6 absent.

Manca-3: BL 2.4–2.8 mm (n = 3). Pereonite-6 short and pereopods-6 rudimentary.

Non-ovigerous female: As holotype, 4.5–5.7 L:W (n = 14), BL 3.65–5.65 mm (n = 33). Pleon 10–13% BL, mean 12.2% (n = 33).

Ovigerous female: As non-ovigerous female but with oostegites; BL 4.5–5.2 mm (n = 2).

Juvenile male: Habitus similar to non-ovigerous female; BL 2.4–4.8mm (n = 7). Pleon 12.1% BL (n = 7). Pleopods present, rudimentary, naked.

Male: Habitus (Fig. 32C) similar to female but slightly stouter, 4.8–5.1 L:W (n = 4); pleon usually slightly longer, 13.0–15.5% BL (n = 5, mean 14.6%), BL 4.1–4.5 mm (n = 5; allotype BL 4.1 mm). Antennule (Fig. 32D) stouter than female, 4.2 L:W overall, articles 1–4 2.0, 0.9, 0.7 and 3.4 L:W respectively (figured specimen), article-4 with incipient division. Pleopods present, typical; peduncle longer than broad, rami oar-shaped.

Distribution

Recorded from the Hikurangi Margin, Kaikoura Canyon, southern flank of the Chatham Rise, and Bounty Trough.

Bathymetric range

Bathyal, 1127–1676 m.

Remarks

This large Libanius species appears as the basal taxon of the NZ clade (Fig. 3). Libanius intonsus n. sp. is the only NZ arthrurid species that sometimes has scattered setules on the basis of pereopods 1–3 (Fig. 21B), although these are also present in A. andriashevi and L. clisicola, possibly as plesiomorphies. Some specimens lack these structures, perhaps through loss during preservation or as variation. This species has similar cephalothorax proportions similar to those of L. tangaroa and a longer, more rounded pleotelson but can be distinguished from this and the other Libanius species by the more slender chela (≈ 2.7 L: W) and carpus of pereopods 2–3, and stouter merus of pereopods 4–6.

The overall sample ratio of males to females is 1: 5.2. No mancae stages have yet been recorded. It is the deepest-occurring arthrurid species within the region and only one specimen of Paralibanius taitonga n. gen. n.sp. (see below) has been recorded in the same sample, NZOI S152, at 1676 m.

• Libanius largitas n. sp.

• LSID urn: lsid: zoobank.org:act:D4229A5B-E442-47BB-9916-493C3B3737B6

• (Figs. 1, 33 and 22–24, 36 C, 37B)

Type material

HOLOTYPE: non-ov. ♀, 3.95 mm, NIWA 173630, TAN1501 Stn Caravel.

PARATYPES: non-ov. ♀, NIWA 173631, TAN1116 Stn 68; 1 manca-2, 3 non-ov. ♀♀, 1 ov. ♀, NIWA 173632, 1 non-ov. ♀ dissected on 2 microslides, NIWA 173633,TAN1501 Stn Caravel.

Type locality

45.64°S 171.50°E, Bounty Trough, NZEEZ, Southwest Pacific, 1127 m.

Etymology

From the Latin noun largitas, “bounty, abundance”; referring to the type locality, itself named for the HMS Bounty, a former merchant collier taken up by the Royal Navy, which sailed past New Zealand under the command of Captain Bligh, September 1788³⁶; used as a noun in apposition.

Diagnosis

Libanius with cephalothorax longer than pereonites 1–2 combined. Pereonite-1 short [≈ 0.25 L: W], without hyposphenium. Pereonite-6 not long [0.56 L: W]. Pleon stout [0.85 L: W], pleonites sometimes indistinct. Pleotelson stout [≈ 0.56 L: W] ≈ 0.7× pleon L. Antennule L intermediate relative to cephalothorax [≈ 0.75×]. Antenna article-2 1.9× article-3 L, distodorsal seta ≈ 0.5× article-3 L; article-4 slender [≈ 7 L: W]. Mandible molar broad coronal. Maxillule endite with one bifid spine. Cheliped basis not quite reaching posterior of cephalothorax; basis just shorter [≈ 0.9×] than merus; merus much longer (≈ 2.5×) than that of carpus ventral margin; chela L: W intermediate [≈ 2.3 L: W], slightly narrower [≈ 0.9×] than carpus, palm dorsal and ventral margins clearly divergent; palm with 3-spined mesial comb. Pereopods 1–3 basis without groups of setules. Pereopod-1 merus inferodistal spine as long as article; carpus fairly slender [≈ 4.1 L: W]. Pereopod-2 carpus with one distal seta. Pereopods 4–6 overall thin [10.8 L: W]; merus L: W intermediate [2.4 L: W], only slightly shorter than carpus [≈ 0.8×]; carpus L: W intermediate [2.8 L: W]; claw longer than propodus [1.3×]. Uropod slightly longer than pleotelson; peduncle geniculate; endopod L: W intermediate [4.9 L: W]; exopod fairly stout [≈ 2 L: W], proximate to endopod.

Description

Holotype non-ovigerous female: Habitus Fig. 22 A, 36 C) fairly stout, 5.6 L: W. Cephalothorax ≈ 1.2 L: W, L reaching half of pereonite-3 (excluding interpereonal gaps); branchial openingFig. . 22B) with setulate fringe, epignath setae sometimes visible. Pereon slightly tapering posteriad, pereonites with weakly convex lateral margins, pereonites 4–6 sometimes with weak process over coxal attachments, 0.40, 0.59, 0.63, 0.0.66, 0.70, and 0.58 L: W respectively (holotype); each with anterolateral seta. Pleon parallel-sided, 10.7% of body, pleonites and tergites/sternites weakly defined, pleonites 1 and 5 slightly longer than rest; pleonites without epimeral seta, pleonite-5 with one supero-epimeral seta. Pleotelson as long as pleonites 2–5 combined, posterior weakly-produced, with two simple setae and two PSS, with one seta anteroventral to uropod insertion (a large specimen has a small conical apex with four setae, the ventral-most pair longer and more deflexed).

Paratype non-ovigerous female (NIWA 173633). Antennule Fig. 22 C) 5 L: W overall; article-1 0.6× L of whole, 3 L: W, with three lateral PSS, distolateral seta and three PSS; article-2 0.33× article-1 L, ≈ 1.4 L: W, with distolateral seta, smaller distomesial seta, and three PSS; article-3 as long as broad, with single distolateral (long) and distomesial (shorter) setae; article-4 slender, 3.1 L: W, with two thin setae, four long setae, and one aesthetasc closely applied one of the setae (fused? ). Antenna Fig. 22D) ≈ 0.75× antennule L; article-1 shorter than broad; article-2 1.4 L: W, dorsal margin not raised; article-3 as long as broad, with longer dorsodistal seta; article-4 1.6× articles 1–3 CL, with one long and two short distal setae, and two distal PSS; article-5 0.75× article-2 L, 3 L: W, with distal seta; article-6 small, with five setae, two possibly fused.

Mouthparts (paratype): Labrum Fig. 23 A) typical. Mandibles Fig. 23B) with left incisor and lacinia unknown (not recovered), molar broad-coronal, with apex similar to that of right mandible; right incisor weakly tricuspid, molar apex slightly depressed, with a few round sub-terminal tubercles and about seven apical spines. Labium Fig. 23 C) medial lobes longer than broad, subtriangular, with apical setules. Maxillule Fig. 23D) endite with sparse ornamentation of microtrichia, apex with seven spines of various thickness. Maxilla not recovered.

Maxilliped Fig. 23E) basal pedestal broader than bases, bases together cuneate, 1.5 L: W; endites typical, endites typical; palp ≈ 0.9× basis L, article-1 as long as broad; article-2 sub-triangular, as long as broad, setation typical, one mesial seta stouter and more pectinate than others; article-3 subrectangular, as long as article-2, 1.7 L: W, setation typical; article-4 slender, subrectangular, shorter than article-3, 3 L: W, setation typical, with longitudinal fringe of setules. Epignath Fig. 23 F) typical, elongate, as long as maxilliped.

Cheliped Fig. 23G–I, 36B) robust, bases occluding cephalothorax ventrum, basis 0.9 L: W, posterior lobe shorter than anterior mass, latter with small dorsolateral seta; merus ventral margin twice long; carpus narrower distally, 1.6 L: W, with round posterior lobe; chela 1.3× carpus L, palm 1.1 L: W; fixed finger ≈ 1.2× palm L, incisive margin with two widely-spaced low teeth; dactylus incisive margin with two peglike spines and distal co-axial spine.

Pereopod-1 Fig. 24 A) overall very thin, 19.3 L: W; basis slender, 7.3 L: W, with proximal superior PSS; merus 2.4 L: W; carpus elongate, subrectangular, ≈ 1.5× merus L, spines typical, with one distal seta; propodus narrower and just shorter than carpus, 5.9 L: W, with superodistal seta, inferodistal spine, and distolateral spine (thinner and mesial), inferior margin with row of spinules, and setule comb near dactylus insertion; dactylus accessory seta not observed, dactylus and unguis together ≈ 0.8× propodus L. Pereopod-2 Fig. 24B) similar to pereopod-1 but basis, merus, carpus and propodus very slightly shorter, but propodus still very slender (5.25 L: W). Pereopod-3 Fig. 24 C) similar to pereopod-2 but basis very slightly shorter.

Pereopod-4 Fig. 24D) basis slender, 4.5 L: W, and as long as those of pereopods 1–3, slightly wider, with one inferior PSS; merus not slender; carpus slender, subrectangular, slightly longer than merus; propodus slender, as long as carpus, 5 L: W, inferior margin with row of small spinules; dactylus longer than unguis, pectinate. Pereopod-5 Fig. 24E) as pereopod-4. Pereopod-6 Fig. 24 F) similar to pereopods 4–5, setation typical.

Uropod Fig. 22E–F) peduncle 1.9 L: W; endopod 1.25× peduncle L, segment-1 slightly longer than segment-2, segment-1 with two large distomesial PSS, segment-2 with one subdistal seta, one small thin, and three long terminal setae, and one terminal PSS; exopod strong, acute, reaching just short of distal of endopod segment-1, with single long subdistal and distal setae.

Manca-2: BL 1.74–1.85 mm (n = 12); pereopods-6 and pleopods absent. Another, 1.3 mm, specimen is in poor condition and may not be this species.

Manca-3: BL 2.26–2.35 mm (n = 3). Pereopod-6 rudimentary. Pleopods absent. Non-ovigerous female. Habitus as holotype, 5.7–6.7 L:W (n = 5); BL 2.61–4.39 mm (n = 9). Pleon 8.5–11.5% BL (n = 8).

Ovigerous female: As non-ovigerous female but pereon slightly dorsoventrally compressed; BL 3.5 mm.

Male: Unknown.

Distribution

Recorded only from the southern flank of the Chatham Rise and Bounty Trough, off the southeastern seaboard of Te Waipounamu South Island.

Bathymetric range

Bathyal, 1011–1127 m.

Remarks

Most similar to L. concertator, L. largitas n. sp. shares many of its pleonal, antennule, antenna, cheliped, and pereopod characters but differs in 33 of the 98 listed characters (Tables S1, S2) among which are a relatively longer pereonite-1, relatively longer antennule, more slender antenna article-4, longer cheliped merus relative to ventral margin of carpus, and a more pereopod-1 carpus and uropod endopod. They may be sister species, or even conspecific, separated by geography, with L. largitas on the southeastern seaboard of NZ, and L. concertator largely on the western side (e.g. Challenger Plateau). No males of this scarce species have been recorded.

• Libanius projectus n. sp.

• LSID urn: lsid: zoobank.org:act:453AED3D-902B-4420-8997-831B65EE9339

• Ocean Census species 46.

• (Figs. 1 and 3, 5 A, C, E, G, 25–28, 32E–F, 36D, 37 A)

Type material

HOLOTYPE: non-ov. ♀, 5.43 mm, NIWA 173634, TAN1501 Stn Caravel. PARATYPES: 28 manca-2, 10 non-ov. ♀♀ (1 dissected on 2 microslides, NIWA 173635), 1 ov. ♀, 7 juv. ♂♂, 5 ♂♂, NIWA 173636, TAN1501 Stn Caravel.

Other material

1 non-ov. ♀ post-dissected remnant, NIWA 27317 (chelipeds on microslide), post-dissected remnant, NIWA 27318, NZOI Stn E416. Both originally deposited as types for unpublished “Libanius projectus” by Jurgen Sieg; 2 non ov. ♀♀, NIWA 13970, NZOI Stn S153; 10 non ov. ♀♀, 1 ♂, NIWA 13771, NZOI Stn S154; juv. ♂, NIWA 173637, TAN0705 Stn 45; 1 non-ov. ♀, NIWA 173638, TAN0705 Stn 48; 2 manca-3, 3 non-ov. ♀♀, 1 juv. ♂, NIWA 173639, 6 manca-3, 5 non-ov. ♀♀, 6 juv. ♂♂, 1 ♂, NIWA 173640, TAN0705 Stn 49; 2 manca-3, NIWA 173641, TAN0705 Stn 160; 2 non-ov. ♀♀, NIWA 173642, TAN0705 Stn 276; 1 juv. ♂, NIWA 173643, TAN1004 Stn 127; 1 manca-2, 1 non-ov. ♀, 1 juv. ♂, NIWA 173644, TAN2402, Stn 37.

Type locality

45.64°S 171.50°E, Bounty Trough, NZEEZ, Southwest Pacific, 1127 m.

Etymology

Adoption of an unpublished nomen proposed by either Karl Lang or Jürgen Sieg for this species, based on the Latin adjective projectus, “projecting, jutting out”; presumably referring to the uropod exopod.

Diagnosis

Libanius with cephalothorax longer than pereonites 1–2 combined. Pereonite-1 short [≈ 0.4 L: W], without hyposphenium. Pereonite-6 not long [0.55 L: W]. Pleon as long as broad, pleonites distinct. Pleotelson stout [≈ 0.75 L: W], 0.75× pleon L. Antennule L intermediate relative to cephalothorax [≈ 0.78×]. Antenna article-2 1.3× article-3 L, distodorsal seta short; article-4 very slender [8.3 L: W]. Mandible molar broad coronal. Maxillule endite with two coarsely pectinate spines. Cheliped basis reaching posterior of cephalothorax; basis clearly longer [1.3x] than merus; merus longer [1.7×] than that of carpus ventral margin; chela L: W intermediate [≈ 2.2 L: W], ≈ carpus W, palm dorsal and ventral margins clearly divergent, with 5-spined mesial comb. Pereopods 1–3 basis without groups of setules. Pereopod-1 merus inferodistal spine as long as article; carpus fairly stout [3.2 L: W]. Pereopod-2 carpus with two distal setae. Pereopods 4–6 overall very thin [≈ 12 L: W]; merus L: W intermediate [2.3 L: W], shorter than carpus [≈ 0.7×]; carpus slender [3.1 L: W]; claw ≈ propodus L. Uropod shorter than pleotelson; peduncle geniculate; endopod L: W intermediate [4.6 L: W]; exopod L: W intermediate [3 L: W], proximate or divergent to endopod.

Description

Holotype non-ovigerous female: Habitus Fig. 25 A, 36D) fairly slender, 6 L: W, BL 5.43 mm. Cephalothorax Fig. 37 A) 1.2 L: W, L reaching half of pereonite-3, 22% of BL. Pereon slightly tapering posteriad, 54% of BL; pereonites with weak convex lateral margins, pereonites 4–6 with weak lateral process over coxal attachments, 0.4, 0.56, 0.62, 0.72, 0.70, and 0.56 L: W respectively; each with anterolateral seta. Pleon parallel-sided, 12.6% of BL, pleonites 1 and 5 slightly longer than the others; tergites and sternites distinct, epimera with seta, that of pleonite-5 long. Pleotelson Fig. 25B) almost as long as pleonites 2–5 combined, 10% of BL; posterior weakly produced, with two simple setae and two PSS, with one seta anterior to uropod attachment; apex conical with four setae, ventral-most longer and more deflexed; anterolateral anal ridges meeting medially, gap between these and pleonite-5 ≈ 30% of pleotelson L.

Paratype non-ovigerous female, NIWA 173635: Antennule Fig. 25 C) article-1 ≈ 0.54× TL, 3.2 L: W, with three lateral PSS, distolateral seta and two or three PSS; article-2 0.3× article-1 L, ≈ 1.4 L: W, with distolateral seta and three PSS; article-3 as long as broad, with single distolateral (long) and distomesial (shorter) setae; article-4 slender, 3.9 L: W, with two thin setae, four long setae, and one aesthetasc closely applied to one of the setae (fused? ). Antenna Fig. 25D) ≈ 0.8× antennule L; article-1 shorter than broad; article-2 ≈ 1.2 L: W, dorsal margin raised (convex), with dorsodistal stiff seta half article-3 L; article-3 slightlyt longer than broad, with longer dorsodistal seta; article-4 1.45× articles 1–3 combined length, with one long and two short distal setae, and three (?) distal PSS; article-5 as long as article-2, 4.3 L: W, with distal seta; article-6 small, with six setae.

Mouthparts (paratype): Labrum Fig. 25 A) typical. Mandibles Fig. 26B–C) with left incisor distally broad in full profile, crenulate, lacinia as long as incisor, subrectangular, molar broad coronal, larger than incisor, with apex bearing three or four small subterminal tubercles and about six sharp spines; right incisor three-cusped, molar similar to that of left mandible. Labium Fig. 26D) medial lobes longer than broad, subtriangular, with apical setules. Maxillule Fig. 26E–F) endite with rows of microtrichia, apex with several fine setae and eight spines of various thickness. Maxilla Fig. 26G) laminate, subrectangular, almost as large as maxilliped endite.

Maxilliped Fig. 27 A–E) basal pedestal broader than bases, bases together cuneate, 1.6 L: W, median ridge with double row of proximal setules; endites typical; palp ≈ 0.9× basis L, article-1 as longer than broad; article-2 sub-triangular, as long as broad, setation typical; article-3 subrectangular, shorter than article-2, twice as long as broad, setation typical; article-4 slender, subrectangular, shorter than article-3, 3.6 L: W, setation typical, with longitudinal fringe of setules. Epignath Fig. 27 F) as long as maxilliped, with large pectinate distal seta.

Cheliped Fig. 27G–I, 37 A) robust; left and right occluding ventrum of cephalothorax, 1.3 L: W, posterior lobe as long as anterior mass, latter with small dorsolateral seta; merus ventral margin long; carpus narrower distally, 1.4 L: W, with round posterior lobe; chela 1.4× carpus L palm 1.1 L: W; fixed finger as long as palm, incisive margin with two widely-spaced low teeth, and larger distal bifid tooth; dactylus without proximomesial spine (?), incisive margin with two peglike spines and distal co-axial spine.

Pereopod-1 Fig. 28 A) overall very thin, 15.6 L: W; basis slender, 7.1 L: W, with proximal superior seta and small PSS; merus 2.2 L: W; carpus elongate, subrectangular, 1.5× merus L, spines typical, with two distomesial setae; propodus narrower but as long as carpus, 5.3 L: W, with superodistal seta and two inferodistal spines, one thinner than other, mesial inferior margin with row of spinules, and setule comb near dactylus insertion; dactylus with accessory seta, unguis slightly longer than dactylus [1.4×], together with dactylus ≈ propodus L. Pereopod-2 Fig. 28B) similar to pereopod-1 but merus, carpus and propodus each slightly shorter. Pereopod-3 Fig. 28 C) similar to pereopod-2 but merus, carpus, propodus and claw each slightly shorter.

Pereopod-4 Fig. 28D) basis slender and as long as those of pereopods 1–3, slightly wider, 5.4 L: W, with one superior and two inferior PSS; merus not slender; carpus slender, subrectangular, 1.2× merus L; propodus slender, slightly longer than carpus, 6 L: W, inferior margin with double row of small spinules; dactylus longer than unguis, pectinate. Pereopod-5 Fig. 28E) as pereopod-4, but basis without superior PSS. Pereopod-6 Fig. 28 F) similar to pereopod–5 but basis with one inferior PSS; propodus setation typical.

Uropod Fig. 25E–F) peduncle 1.8 L: W; endopod almost as long as peduncle, segments about equal in length, segment-1 with two large distomesial PSS, segment-2 with one subdistal seta, three long, two small thin, terminal setae and one (?) terminal PSS; exopod strong, acute, divergent from endopod, reaching half endopod L, with single long subdistal and distal setae.

Manca-2. BL 1.74–2.4 mm (n = 20); pereonite-6 very short; pereopods-6 and pleopods absent.

Manca-3. BL 2.0–2.5 mm (n = 8); pereopods-6 rudimentary; pleopods absent.

Non-ovigerous female: As holotype, 5.25–6.0 L: W (mean 5.5, n = 16), BL 3.3–5.3 mm (n = 27). Pleon 10.1–13.5% BL (mean 11.9%, n = 27).

Ovigerous female: As non-ovigerous female but pereon slightly dorsoventrally compressed; BL 4.6 mm (n = 1).

Juvenile male: Habitus similar to non-ovigerous female; 5.1–5.8 L:W (mean 5.3, n = 9), BL 2.8–3.9 mm (n = 15). Pleopods present, rudimentary, naked.

Male: Habitus (Fig. 32E) similar to female but slightly stouter, 5.5–6.1 L:W (n = 5; allotype 6.0 L:W); pleon generally longer, 12.2–16.8% BL (mean 15.4%, n = 7, allotype 16.7%); BL 4.3–4.7 mm (n = 7; allotype BL 4.6 mm). Antennule stouter, 4.3 L:W overall, articles 1–4 2.2, 0.9, 0.6 and 3.1 L:W respectively (allotype), article-4 with incipient division. Pleopods (Fig. 32F) near-rigid, held in tent-like configuration; peduncle slightly longer than broad; rami about equal in size and shape, 2.9 L:W, endopod with superodistal seta and fringe of eight setae, shorter than ramus; exopod with distal fringe of nine setae.

Distribution

Recorded from the southern slope of the southern flank of the Chatham Rise and Bounty Trough, as well as the Hikurangi Margin.

Bathymetric range

Bathyal, 982–1386 m.

Remarks

This species was one of those NZ tanaids starting to receive taxonomic attention by Karl Lang and Jürgen Sieg in the 1970–1980 period, which was left uncompleted, although unpublished types were deposited. In the second phylogenetic analysis (Fig. 3), L. projectus n. sp. nests within a clade of other NZ Libanius species but has a proportionally shorter cephalothorax than L. tangaroa n. sp. (see below) and a longer pleotelson, smooth pereopod bases, and well-defined pleonites.

Of 55 post-manca specimens of certain life stage 23 are males of various stages of development, resulting in a relatively low sex ratio of 1: 1.4 males to females. The largest number of specimens in a single sample is 24, from TAN0705 Stn 49, at 1237 m on the southern flank of the Chatham Rise.

• Libanius tangaroa n. sp.

• LSID urn: lsid: zoobank.org:

• Ocean Census species 47.

• (Figs. 1, 3 and 29–31, 32G–H, 36E)

Type material

HOLOTYPE: non-ovigerous (non-ov.) ♀, NIWA 173645, 3.65 mm, TAN1116 Stn 89. PARATYPES: 1 non-ov. ♀, dissected on 2 microslides, NIWA 173646, TAN0705 Stn 83; 1 ♂, NIWA 173647, TAN1116 Stn 89; 4 non-ov. ♀♀ (one partly dissected on 1 microslide, NIWA 173648), 2 juv. ♂♂ (1 with a pleopod dissected on microslide), NIWA 173649, TAN0705 Stn 251; 1 non-ov. ♀, 1 ♂, NIWA 173650, TAN1116 Stn 31; 2 ♂♂, NIWA 173651, TAN1116 Stn 33.

Other material

1 non-ov. ♀, NIWA 142262, NZOI Stn F753; 1 non-ov. ♀, NIWA 12821, NZOI Stn S138; 1 non-ov. ♀, NIWA 173652, TAN0705 Stn 24; 1 manca-2, 1 non-ov. ♀, 2 ♂♂, NIWA 173653, TAN1116 Stn 89; 2 non-ov. ♀♀, NIWA 96069, 1 ov. ♀, 1 juv. ♂, NIWA 96068, TAN1306 Stn 30; one ♂, NIWA 173654, TAN2303 Stn 22; 1 non-ov. ♀, NIWA 173655, TAN2303 Stn 47; 1 ov. ♀, NIWA 173656, TAN2303 Stn 85; 1 manca-3, 1 non-ov. ♀, NIWA 173657, TAN2402, Stn 11.

Type locality

43° 29.76’S 178° 19.84’E, near-crest southern slope of the Chatham Rise, NZEEZ, Southwest Pacific, 463 m.

Etymology

From Te reo Māori, Tangaroa, an atua (ancestor) connected to the ocean; also, for RV Tangaroa, the principal research vessel of NIWA.

Diagnosis

Libanius with cephalothorax relatively large, as long as pereonites 1–3 combined. Pereonite-1 short [< 0.4 L: W], without hyposphenium; pereonite-6 not long [≈ 0.5 L: W]. Pleon stout [0.9 L: W], pleonites well defined. Pleotelson fairly stout [0.65 L: W], ≈ 0.75× pleon L. Antennule short relative to cephalothorax [0.6×]. Antenna article-2 clearly longer [1.7×] than article-3; article-4 L: W intermediate [≈ 5 L: W]. Mandible molar broad coronal. Maxillule endite with one finely pectinate spine. Cheliped basis reaching posterior of cephalothorax; basis longer than merus; merus ≈ 2× carpus ventral margin L; chela L: W intermediate [≈ 2.4 L: W], slightly narrower than carpus, palm dorsal and ventral margins subparallel, with 3-spined mesial comb. Pereopods 1–6 basis without groups of setules. Pereopod-1 merus inferodistal spine L shorter than merus; carpus slender [4.3 L: W]. Pereopod-2 carpus with one distal seta. Pereopods 4–6 overall very thin [14.4 L: W]; merus slender [2.5 L: W]; propodus fairly stout [≈ 4.6 L: W]; claw shorter than propodus. Uropod just shorter than pleotelson; peduncle arcuate; endopod L: W intermediate [3.7 L: W], ≈ peduncle L; exopod stout [2.5 L: W], proximate to endopod.

Description

Holotype non-ovigerous female: Habitus Fig. 29 A, 36E) fairly stout, 4.9 L: W. Cephalothorax 1.2 L: W, 25% of body length. Pereon slightly tapering posteriad, pereonites 1–3 with weakly convex lateral margins, pereonites 4–6 with weak process over coxal attachments, 0.31, 0.47, 0.53, 0.63, 0.68, and 0.56 L: W respectively; each with anterolateral seta, coxal seta visible in dorsal view on pereonites 4–6 at least. Pleon parallel-sided, 11.6% of BL, pleonites 1 and 5 slightly longer than rest; tergites and sternites distinct, pleonite-5 with long epimeral seta and shorter anterodorsal seta. Pleotelson Fig. 29B) almost as long as pleonites 2–5 combined, ≈ 0.65 L: W, lateral margins weakly tapering posteriad, posterior weakly-produced, with two simple setae and two PSS, with small conical apex with four setae (two longest deflexed); anterolateral anal ridges meeting medially, and one seta anteroventral to uropod insertion.

Paratype non-ovigerous female, NIWA 173646: Antennule Fig. 29 C) 0.6× cephalothorax L (holotype), ≈ 4.4 L: W overall; article-1 ≈ 0.56× L of whole, 2.5 L: W, with two lateral PSS, distolateral seta and two or three PSS; article-2 0.3× article-1 L, 1.2 L: W, with distolateral seta and three PSS; article-3 ≈ 1.4 L: W, with single distolateral (long) and distomesial (shorter) setae; article-4 slender, 4 L: W, with two thin setae, four long setae, and one aesthetasc closely applied one of the setae (fused? ). Antenna Fig. 29D) 0.8× antennule L; article-1 shorter than broad; article-2 ≈ 1.2 L: W, dorsal margin slightly raised (convex); article-3 smaller than article-2, slightly longer than broad, dorsodistal seta longer than that of article-2; article-4 1.4× articles 1–3 CL, 5 L: W, with one short and two long distal setae, and four distal PSS; article-5 slightly longer than article-3, 3 L: W, with distal seta; article-6 small, with six setae, three possibly fused.

Mouthparts: Labrum Fig. 30 A) typical; epistome round in lateral view. Mandibles Fig. 30B–C) with left incisor narrow but strongly crenulate, lacinia as large as incisor, subrectangular with irregular crenation, molar coronal, bearing a few small sub-terminal tubercles and about eight blunt terminal spines; right incisor four-cusped, molar similar to that of left mandible, as large as or larger than incisor, slightly deflexed. Labium Fig. 30D) medial lobes longer than broad, subtriangular, with apical setules. Maxillule Fig. 30E) endite apex with setules and seven spines of various thickness, one finely pectinate; palp with two long unequal setae. Maxilla not observed.

Maxilliped Fig. 30 F–I) basal pedestal broad cordiform, bases together cuneate, narrower, 1.4 L: W, with slight median ridge with several proximal setules; endites typical, but sub-mesial tubercle broad and shallow, mesial tubercle smaller and triangular, and one distal seta; palp ≈ 0.75× basis L, article-1 longer than broad; article-2 triangular, as long as broad, setation typical, with one mesial seta stronger and more pectinate than others; article-3 subrectangular, shorter than article-2, 1.6 L: W, setation typical, setae; article-4 slender, subrectangular, just shorter than article-3, 3.5 L: W, setation typical, with several distal setules. Epignath Fig. 31 J) typical.

Cheliped Fig. 30 K–L) robust; basis 1.4 L: W, 1.25 merus L, posterior lobe almost reaching posterior of cephalothorax, about as long as anterior mass, latter with dorsolateral seta; merus ventral margin 2.3x longer than that of carpus; carpus narrower distally, 1.7 L: W; chela 1.2× carpus L but slightly narrower, 2.4 L: W, palm dorsal and ventral margins almost parallel (very weak flare), 1.3 L: W, with mesial comb of three spines; fixed finger as long as palm, incisive margin with two widely-spaced triangular teeth, and larger distal bifid tooth; dactylus incisive margin with one distal co-axial spine.

Pereopod-1 Fig. 31 A) basis slender, 7.3 L: W, with proximal superior seta; merus 2.5 L: W, slender inferodistal spine shorter than merus; carpus elongate, 1.5× merus L, distally wider, 4.3 L: W, spines typical and with one distomesial seta; propodus narrower but as long as carpus, 5.9 L: W, with superodistal seta, coaxial inferodistal spine and distolateral spine, mesial inferior margin with row of spinules; unguis clearly longer than dactylus (1.7×), together with dactylus ≈ 0.9× propodus L. Pereopod-2 Fig. 31B) similar to pereopod-1 but basis, merus, carpus and propodus each slightly shorter. Pereopod-3 Fig. 31 C) similar to pereopod-2 but basis, merus, carpus, propodus and claw each slightly shorter; carpus with one distomesial seta.

Pereopod-4 Fig. 31D) basis slender but of similar width to those of pereopods 1–3, 6.5 L: W, with two inferior PSS; merus ≈ 2.5 L: W; carpus slender, 1.5× merus L, 3.8 L: W; propodus slender, slightly longer than carpus, 4.6 L: W, inferior margin with double row of small spinules; dactylus longer than unguis, pectinate, together ≈ 0.8× propodus L. Pereopod-5 Fig. 31E) as pereopod-4, but basis with one inferior PSS. Pereopod-6 Fig. 31 F) similar to pereopods 4–5 but basis without PSS; propodus setation typical.

Uropod Fig. 29E) ≈ 0.8× as long as pleotelson; peduncle slightly arcuate, twice as long as broad; exopod strong, proximate to endopod or slightly divergent, ≈ 2.5 L: W (mid-length), reaching half endopod L, with single long subdistal and distal setae; endopod almost as long as peduncle, ≈ 3.7 L: W, segment-1 with two large distomesial PSS, segment-2 with one subdistal seta, three terminal setae and two small terminal PSS.

Manca-2. BL 1.7 mm (n = 1); pereopods-6 and pleopods absent.

Manca-3. BL 2.4 mm (n = 1); pereopods-6 rudimentary, pleopods absent.

Non-ovigerous female: As holotype, 4.0–5.5 L: W (n = 9); BL 2.7–4.8 mm (n = 14). Pleon 10.2–13.0% of BL (n = 14, mean 11.6%).

Ovigerous female: As non-ovigerous female but with oostegites; BL 4.0 mm (n = 1).

Juvenile male: Habitus similar to non-ovigerous female; BL 2.4–3.5 mm (n = 6). Pleon 11.5–13.2% of BL (n = 5, mean 12.1%). Pleopods present, rami oval, ≈ 2 L:W, naked.

Male: Habitus (Fig. 32G) similar to female but slightly stouter, 4.6–4.9 L:W (n = 6 allotype 4.6 L:W); pleon generally longer, 13.9–15.6% BL (n = 7, mean 14.6%; allotype 14.7%), with distinct tergites and sternites, epimera with seta; BL 3.1–3.2 mm (n = 6). Antennule stouter, 3.8 L:W overall, articles 1–4 1.9, 1.1, 0.9 and 2.8 L:W respectively (allotype). Pleopods (Fig. 32H) peduncle 1.4 L:W; rami of similar straplike shape, but exopod slightly longer, ≈ 3 L:W; endopod with subdistal superior seta and terminal fringe of seven setae, exopod with terminal fringe of nine setae.

Distribution

Recorded from nine sites on the southern slope and crest of the Chatham Rise, and the Memoo Gap; one from the Bounty Trough.

Bathymetric range

Shallow bathyal, 463–790 m.

Remarks

This Libanius species is distinguishable mainly by the relatively large cephalothorax compared to the other Libanius species (25–26% of BL in males, mean 25%, n = 6); 23–28% in females, mean 26%, n = 14; Table 2), and relatively short pereonite-1 and antennules. The short pleotelson with a narrow gap between the anal valves and the anterior margin (Fig. 29B) further distinguishes L. tangaroa n. sp. from L. projectus. The most likely species in NZ waters that it could be confused with is L. intonsus with a similar ‘large-cephalothorax’ habitus, but this taxon is generally larger, has proportionately longer pereonites 1–3, setules on the pereopods 1–3, and a stouter merus on pereopods 2 and 4.

Of 23 post-manca specimens, nine are males of various stages of development, yielding a relatively low sex ratio of 1: 1.6 males to females. The largest number of specimens in a single sample is six, from TAN0705 Stn 251, at 525 m near the crest of the Chatham Rise and L. tangaroa appears to be largely, but not completely, separated bathymetrically from the other five NZ species.

Diagnosis

Arthrurid with pereonites 1–6 lateral margins with supracoxal projections; pereonite-1 without hyposphenium. Pleon narrower than pereon and pleotelson; pleonites distinct. Pleotelson pentagonal. Antennule not long relative to cephalothorax [0.6–0.8×]; article-1 not slender [≈ 2.7 L: W]. Antenna article-2 about as long as broad, dorsal margin simple; article-3 dorsal seta longer than article; article-5 stout-short [2.3 L: W]. Mandible molar coronal, with low tubercles and longer spines. Maxillule endite with one bifid spine. Maxilliped bases with distomedial setulate process. Chelipeds attached anteriad on cephalothorax ventrum, separated from posterior margin by broad transverse sclerite; carpus dorsal margin smooth. Pereopods 1–6 basis smooth. Pereopod-1 stout sticklike [11 L: W overall]; merus inferodistal spine long [= article L]; carpus with one distal seta; propodus with inferodistal and distolateral seta. Pereopods 2–3 carpus with one distal seta. Pereopods 4–6 stout sticklike [< 10 L: W]; ischium with one seta; claw slightly clearly longer [> 1.2×] than propodus. Uropod as long as pleotelson; peduncle geniculate; endopod bisegmented, L:W intermediate [3 L: W]; exopod proximate to endopod.

Type species

Paralibanius taitonga n. gen. n. sp. by original designation here.

Etymology

A combination of the genus nomen Libanius and the Greek prefix ‘para,’ suggesting affinity or likeness. Gender masculine.

Geographic range

Great South Basin, Southwest Pacific.

Remarks

The principal diagnostic characters for this new genus are the advanced position of the chelipeds, short antenna article-5, and relatively stout pereopods. The appearance of the cheliped-cephalothorax configuration almost mimics that of the agathotanaid genus Paragathotanais but with the presence of a (short) posterior lobe on the basis.

• Paralibanius taitonga n. sp.

• LSID urn: lsid: zoobank.org:act:025C0D9D-1563-4F06-8917-B2A7EE70CAC8

• Ocean Census species 48.

• (Figs. 1, 3 and 33–35, 32I, 36 F, 37D)

Type material

HOLOTYPE: non-ov. ♀, 4.3 mm, NIWA 173658, TAN1902, Stn 67. PARATYPES: 1 non-ov. ♀, dissected on 3 microslides, NIWA 173659, TAN2202 Stn 93; 1 juv. ♂, NIWA 173660, TAN1902, Stn 42; 1 non-ov. ♀, 1 ov. ♀, 2 ♂♂, NIWA 173661, TAN2402, Stn 47.

Other material

1 ♂, NIWA 173662, NZOI Stn S152; 1 juv. ♂, NIWA 173663, TAN1501, Stn REF5; 1 manca-2, NIWA 173664, TAN1902, Stn 133; 1 manca-2, NIWA 173665, TAN1902, Stn 135; 1 manca-3, NIWA 173666, TAN1902, Stn 167; 1 manca-3, NIWA 173667, TAN1902, Stn 186; 1 manca-3, NIWA 173668, TAN1902, Stn 218; 1 manca-3, NIWA 173669, TAN2202, Stn 74; 1 juv. ♂, NIWA 173670, TAN2202, Stn 76; 1 manca-3, NIWA 173671, TAN2202, Stn 83; 14 manca-2, NIWA 173672, TAN2202, Stn 93; 1 ♂, NIWA 173673, TAN2402 Stn 53; 1 juv. ♂, NIWA 173674, TAN2402, Stn 55.

Type locality

46.9°S 171.6°E, Great South Basin, NZEEZ, Southwest Pacific, 1284–1287 m.

Etymology

Use of Te reo Māori noun taitonga ‘the South’, referring to the southerly NZ locality recorded for this species; used as a noun in apposition.

Diagnosis

As for genus.

Description

Holotype non-ovigerous female: Habitus Fig. 33 A, 36 F) fairly slender, 6.4 L: W; cuticle brittle and finely pitted, BL 4.3 mm. Cephalothorax 1.29 L: W, as long as pereonites 1–2 combined. Pereon slightly tapering posteriad, pereonites 1–3 with weakly convex lateral margins, pereonites 4–6 with weak process over coxal attachments, ≈ 0.6, 0.8, 0.0.8, 0.9, 0.9, and 0.6 L: W respectively; each with anterolateral seta. Pleon parallel-sided, 0.92 L: W, 10% of BL, 1.4× pereonite-6 L, pleonites 1 and 5 slightly longer than rest; tergites and sternites distinct, pleonite-5 with epimeral seta and anterodorsal seta. Pleotelson almost as long as pleonites 2–5 combined, ≈ 0.7 L: W, posterior weakly-produced, with two simple setae and two PSS, with small conical apex with four setae (two longest deflexed); anterolateral anal ridges meeting medially, and one seta anteroventral to uropod insertion.

Paratype non-ovigerous female, NIWA 173659: Antennule Fig. 33B) 0.6× cephalothorax L (holotype), ≈ 4.7 L: W overall; article-1 ≈ 0.6× L of whole, 2.7 L: W, with three lateral PSS, distolateral seta and two or three PSS; article-2 0.3× article-1 L, 1.2 L: W, with distomesial seta, long distolateral seta and two PSS; article-3 ≈ 0.9 L: W, with single distolateral and distomesial setae and distomesial PSS; article-4 slender, 3 L: W, with two short setae, four long setae, and one aesthetasc. Antenna Fig. 33 C) 0.7× antennule L; article-1 shorter than broad; article-2 slightly longer than broad, dorsal margin slightly raised (convex), with a few setules; article-3 smaller than article-2, slightly longer than broad, dorsodistal seta longer than that of article-2; article-4 1.3× articles 1–3 CL, 5.5 L: W, with two short and two long distal setae, and two distal PSS; article-5 shorter than article-3, 2.3 L: W, with distal seta; article-6 small, with four setae.

Mouthparts: Labrum Fig. 34 A) typical. Mandibles Fig. 34B–E) with left incisor narrow, bifid, lacinia as large as incisor, narrow; molar bearing about eight terminal spines; right molar with rugose proximal margin, incisor apex not observed, molar similar to that of left mandible. Labium not observed. MaxilluleFig. 34 F) endite apex with setules and eight spines of various thickness, one bifid. Maxilla Fig. 34G) longer than broad.

Maxilliped Fig. 34 H) basal pedestal broad cordiform, bases together cuneate, narrower, 1.5 L: W, with slight median ridge with several proximal setules; endites typical, but setae not observed (broken? ); palp ≈ basis L, article-1 longer than broad; article-2 triangular, as long as broad, setation typical, lateral seta long, with one mesial seta stronger and more pectinate than others; article-3 subrectangular, as long as article-2, setation typical; article-4 slender, subrectangular, just shorter than article-3, 2.3 L: W, setation typical. Epignath Fig. 34I) typical.

Cheliped Fig. 33B, 34 J–K, 37D) robust; basis 1.4 L: W, ventral margin 0.9× that of merus, posterior lobe clearly anterior of rear margin of cephalothorax, smaller than anterior mass, latter without dorsolateral seta (possibly broken); merus ventral margin 3× longer than that of carpus; carpus narrower distally, 1.5 L: W; chela 1.25× carpus L but slightly narrower, ≈ 2 L: W, palm 0.9 L: W, dorsal and ventral margins divergent, with mesial comb of three spines; fixed finger 1.2× palm L, incisive margin with distal tooth; dactylus simple, with proximo-mesial spine.

Pereopod-1 Fig. 35 A) 11 L: W overall; coxa annular with seta (lost on figured specimen); basis fairly slender, 5 L: W, with proximal superior PSS; merus 1.6 L: W, slender inferodistal spine as long as merus; carpus 1.4× merus L, 2.5 L: W, spines typical, with one distomesial seta; propodus narrower and longer than carpus, 4.2 L: W, with superodistal seta, distolateral spine, and stronger sub-coaxial inferodistal pectinate spine, mesial inferior margin with row of spinules; dactylus with accessory seta, unguis clearly longer than dactylus, together with dactylus ≈ 1.1× propodus L. Pereopod-2 Fig. 35B) similar to pereopod-1 but basis, merus, carpus and propodus each slightly shorter; propodus without distolateral spine. Pereopod-3 Fig. 35 C) similar to pereopod-2.

Pereopod-4 Fig. 35D) not sticklike, 8.7 L: W overall; basis fairly slender, 4 L: W, but slightly wider than those of pereopods 1–3, with two inferior PSS; merus ≈ 1.6 L: W; carpus slender, 1.7× merus L, 2.8 L: W; propodus slender, as long as carpus, 4.2 L: W, inferior margin with double row of small spinules; dactylus longer than unguis, pectinate, together slightly longer than propodus. Pereopod-5 Fig. 35E) as pereopod-4, but basis with one inferior PSS. Pereopod-6 Fig. 35 F) similar to pereopods 4–5 but basis without PSS; propodus setation typical.

Uropod Fig. 33D) ≈ 0.8× as long as pleotelson; peduncle proximally geniculate, 1.7 L: W; endopod as long as peduncle, ≈ 3 L: W, segment-1 1.5 L: W, with two large distomesial PSS, segment-2 as along as segment-1, with one subdistal seta, three long and one short terminal setae and two small terminal PSS; exopod strong, proximate to endopod or slightly divergent, ≈ 2.8 L: W (mid-length), reaching half endopod L, with single long subdistal and distal setae.

Manca-2: Body 5.7–6.1 L: W (n = 7), pereonite-6 very short; BL 1.74–1.85 mm (n = 12). Pereopod-6 absent.

Manca-3: Body 5.5–6.1 L: W (n = 2), pereonite-6 very short; BL 2.26–2.35 mm (n = 3). Pereopod-6 rudimentary.

Non-ovigerous female: As for holotype, 6.1–6.7 L: W (n = 4); BL 3.8–4.4 mm (n = 4). Pleon 9.6–10.8% of BL (n = 4).

Ovigerous female: As for non-ovigerous female but with oostegites, 6.5–6.6 L: W (n = 2); BL 3.4–3.7 mm (n = 2).

Juvenile male: Habitus similar to non-ovigerous female, 5.4–6.8 L: W (n = 5); BL 2.4–3.3 mm (n = 6). Pleon 10.2–11.7% of BL (n = 6). Pleopods present, rami oval, ≈ 2 L: W, naked.

Male: Habitus Fig. 32 H) similar to female but slightly stouter, 5.4–6.4 L: W (n = 3); pleon generally longer, 10.3–14.7% BL (n = 3), BL 3.4–3.7 mm (n = 3). Antennule stouter, 4.2 L: W overall.

Distribution

Recorded from three sites in the Bounty Trough, eleven sites in the Great South Basin, and one from the Challenger Plateau.

Bathymetric range

Bathyal, 1284–1676 m, most ≈ 1300 m.

Remarks

This species is the most recognisable among the Antipodean species of arthrurids, with its diagnostic cheliped attachment. Its distribution is predominantly southeastern in the NZ region but with a putative single record (and singleton) from the western seaboard of Te Waipounamu South Island.

Material

1 manca-3, TAN1004, Stn 38; 1 manca-3, TAN1004, Stn 53.

Remarks

This category is for specimens that could not be easily placed in any of the four nominal species because of the poor state of preservation, incompleteness, or falling outside of the morphological envelope in some way.