Uroptychus poorei, Baba, 2018

Baba, Keiji, 2018, Chirostylidae of the Western and Central Pacific: Uroptychus and a new genus (Crustacea: Decapoda: Anomura), Tropical Deep-Sea Benthos (Mémoires du Muséum national d'Histoire naturelle 212), pp. 1-612 : 414-418

Uroptychus poorei n. sp.

Figures 205 , 206

TYPE MATERIAL — Holotype: New Caledonia, Norfolk Ridge. NORFOLK 1 Stn CP 1714, 23°22’S, 168°03’E, 257- 269 m, 26.VI.2001, ♂ 3.1 mm ( MNHN-IU-2011-5967 ) . Paratypes: New Caledonia, Norfolk Ridge. CHALCAL 2 Stn CH 03, 24°48’S, 168°09’E, 257 m, 27.X.1986, with Chironephthya sp. ( Alcyoniina : Nidaliidae ), 1 ov. ♀ 2.0 mm ( MNHN- IU-2011-5966) . SMIB 4 Stn DW45, 24°45’S, 168°08’E, 245-260 m, 08.III.1989, 1 ♂ 2.5 mm (MNHN-IU-2011-5963). Beryx 11 Stn CP17, 24°48.00’S, 168°08.89’E, 250-270 m, 16.X.1992, 1 ov. ♀ 2.9 mm (MNHN-IU-2011-5965).

ETYMOLOGY„ Named for Gary C.B. Poore for his friendship and for his leadership to organize projects of squat lobster studies.

DISTRIBUTION„ Norfolk Ridge; 245- 270 m.

SIZE„ Males, 2.5-3.1 mm; ovigerous females, 2.0- 2.9 mm.

DESCRIPTION„ Small species. Carapace: Broader than long (0.8-0.9 × as long as broad); greatest breadth 1.5-1.6 × distance between anterolateral spines. Dorsal surface unarmed, moderately convex from side to side, slightly convex on gastric and cardiac regions in profile, with weak depression between; with distinct ridge along branchial margin. Lateral margins divergent posteriorly, with strong anterolateral spine directed straight forward, overreaching lateral orbital spine, unarmed elsewhere. Rostrum directed slightly ventrally, relatively narrow, sharp triangular, with interior angle of 30°, ending in sharp tip; dorsal surface concave; lateral margin smooth; length 0.4 × that of remaining carapace, breadth about half carapace breadth at posterior carapace margin. Lateral orbital spine small, situated directly mesial to anterolateral spine. Pterygostomian flap anteriorly angular, produced to distinct spine, smooth on surface.

Sternum: Excavated sternum convex or subtriangular on anterior margin, surface with weak ridge in midline. Sternal plastron about as long as broad, lateral extremities subparallel between sternites 4-7. Sternite 3 slightly depressed from level of sternite 4 in ventral view; anterior margin moderately concave in broad V-shape with narrow or broad deep median notch separating small submedian spines. Sternite 4 having anterolateral margin somewhat convex and anteriorly blunt angular; posterolateral margin as long as anterolateral margin. Anterolateral margins of sternite 5 subparallel, anteriorly rounded, 1.5-1.8 × longer than posterolateral margin of sternite 4.

Abdomen: With sparse long setae. Somite 1 convex from anterior to posterior. Somite 2 tergite 2.0-2.5 × broader than long; pleural lateral margin slightly concave, nearly subparallel in dorsal view, posterolaterally rounded. Pleuron of somite 3 with broadly rounded lateral margin. Telson half as long as broad; posterior plate 1.2-1.4 × length of anterior plate, posterior margin gently rounded or convex, not emarginate.

Eye: Long relative to breadth (length twice breadth), distally narrowed, lateral margin convex, slightly falling short of rostral tip. Cornea relatively small, length less than one-third that of remaining eyestalk.

Antennule and antenna: Ultimate article of antennular peduncle 2.9-3.3 × longer than high. Antennal peduncle overreaching cornea, reaching rostral tip. Article 2 with strong lateral spine. Antennal scale 1.2-1.3 × broader than article 5, fully or barely reaching midlength of article 5 (varying from slightly overreaching article 4 to terminating in midlength of article 5). Article 4 with tiny ventral distomesial spine. Article 5 unarmed, 1.4 × longer than article 4, breadth 0.5-0.6 × height of ultimate article of antennule. Flagellum of 9-14 segments not reaching distal end of P1 merus.

Mxp: Mxp1 with bases broadly separated. Mxp3 basis without denticle on mesial ridge. Ischium with flexor margin rounded distally, crista dentata with about 20 distally diminishing denticles. Merus 2.3 × longer than ischium, without distolateral spine; flexor margin well ridged along distal third of length, without spine; mesial face concave. Carpus unarmed.

P1: 7.2-7.3 × (males), 6.5-6.7 × (females) longer than carapace, slender, with sparse setae of moderate length, smooth without spine. Ischium with small dorsal spine, unarmed on ventral surface and ventromesial margin. Merus 1.6 × longer than carapace. Carpus 1.4 × longer than merus. Palm distally broadened in males, medially somewhat broader in females, 3.7-4.0 × (males), 4.9-6.7 × (females) longer than broad, 1.0 × (males), 0.8-0.9 × (females) length of carpus, somewhat depressed. Fingers slightly crossing when closed, gaping in males, not gaping in females, sparingly with setae of moderate length; movable finger 0.3-0.4 × as long as palm, opposable margin with prominent, proximally lowering process at midpoint of gaping portion; no longitudinal groove on opposite side of fixed finger.

P2-4: Setose (with long setae), relatively thick mesio-laterally; P2 merus 0.8 × length of carapace, 1.0-1.1 × length of P2 propodus; P3 merus 0.9 × length of P2 merus, 0.9 × length of P3 propodus; P4 merus 0.9 × length of P3 merus, 0.9-1.0 × (males), 0.7-0.8 (females) length of P4 propodus; length-breadth ratio, 3.7-3.8 on P2, 3.4 on P3, 3.3-3.5 on P4; dorsal margin not cristate but rounded, unarmed. Carpi subequal, 0.3-0.4 × (P2) or 0.3 × (P3 and P4) as long as propodi,‰.7-0.8 × as long as dactyli. Propodi shorter on P2 than on P3-4; flexor margin nearly straight, with pair of slender terminal spines only. Dactyli relatively stout, 1.2-1.4 × longer than carpi on P2-4, 0.4 × as long as propodi on P2-4; flexor margin nearly straight, with 6 relatively loosely arranged spines, ultimate slender, penultimate prominent, about 2 × broader than antepenultimate, preceded by proximally diminishing spines perpendicular to flexor margin, proximal-most obliquely directed.

Eggs. Number of eggs carried, 2-7; size, 0.82 × 0.98 mm - 0.92 × 1.04 mm.

REMARKS — The carapace shape and the distally narrowed eyes in the new species are very much like those of U. amabilis Baba, 1977 from off Noumea, New Caledonia. Uroptychus poorei is readily distinguished from that species by the following differences: sternite 3 has the anterior margin deeply excavated representing a broad V-shape instead of being shallowly excavated and medially transverse; sternite 4 has the anterolateral margin as long as instead of much longer than the posterolateral margin; the antennal peduncle has a small distomesial spine on article 4 only instead of a distinct spine on each of articles 4 and 5; the antennal scale terminates at most in the midlength, instead of slightly falling short of the end, of article 5; the Mxp3 merus is unarmed instead of bearing a distinct distolateral spine and a few flexor marginal spines; and the penultimate of the flexor marginal spines of P2-4 dactyli is much stronger than instead of subequal to the antepenultimate spine. In addtion, U. amabilis is a shallow water species taken in 30 m, whereas U. poorei ranges between 250 and 270 m.

The original description of U. bacillimanus Alcock & Anderson, 1899 is very brief, but the illustrations ( Alcock & Anderson, 1899: pl. 45, figs 3, 3a) show that the species is somewhat similar to this new species, although the distal parts of the P2-4 dactyli are not clearly depicted. At my request in 1977, K. K. Tiwari, then the director of the Zoological Survey of India, Calcutta, provided me with illustrations of one of the syntypes ( Figure 207 ). In fact, its P2-4 spination is nearly the same as that of the new species, but the eyes are not distally narrowed, the anterolateral spine of the carapace is separated from and not closer at base to the lateral orbital spine in dorsal view, and the antennal article 2 has no distolateral spine, all to mention obvious differences from U. poorei .

Figures

FIGURE 205 Uroptychus poorei n.sp.,holotype,male 3.1 mm (MNHN-IU-2011-5967).A, carapace and anterior part of abdomen,proximalpart of right P1 included,dorsal. B, same,setae omitted,lateral.C, sternal plastron,with excavated sternum and basal parts of Mxp1. D, telson.E, left antenna,ventral.F, left Mxp3, setae omitted,ventral.G, same,lateral. Scale bars:1 mm.

FIGURE 206 Uroptychuspoorei n.sp.,A-G,holotype,male 3.1 mm(MNHN-IU-2011-5967);H-J, ovigerous female paratype (MNHN-IU-2011-5966). A, right P1, proximal part, lateral.B, same,proximal part,setae omitted, ventral.C, same,distal three articles,dorsal. D, right P2, lateral.E, same,distal part,setae omitted,lateral.F, right P3,lateral.G, same,distal part,lateral.H, left P2,lateral.I, right P3,lateral. J, right P4, lateral. Scale bars: 1 mm.

FIGURE 207 Uroptychus bacillimanus Alcock & Anderson,1899,female syntype.A, carapace and anterior part of abdomen,dorsal.B, anterior part of sternal plastron. C, left antenna, ventral. D, right P3, distal part, setae omitted. Scale bars: 1 mm (Illustrated by K.K.Tiwari,1977).