Uroptychus enriquei, 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 : 204-207

Uroptychus enriquei n. sp.

Figures 90 , 91

TYPE MATERIAL — Holotype: New Caledonia, Norfolk Ridge. BERYX 11 Stn CP53, 23°48’S, 168°17’E, 540-950 m, 21.X.1992, ov. ♀ 10.8 mm ( MNHN-IU-2011-5953 ) . Paratypes: Philippines. MUSORSTOM 3 Stn CP105, 13°52’N, 120°30’E, 398-417 m, 1.VI.1985, 1 ov. ♀ 7.9 mm (MNHN-IU-2011-5957) . Solomon Islands. SALOMON 2 Stn CP2227, 6°37.2’S, 156°12.7’E, 508-522 m, 28.X.2004, 1 ♀ 7.0 mm (MNHN-IU-2011-5956) . New Caledonia, Norfolk Ridge. SMIB 3, Stn DW21, 22°59.2’S, 167°19.0’E, 525 m, 24.V.1987, 1 ♂ 9.5 mm (MNHN-IU-2011-5954) . MUSORSTOM 4 Stn CP216, 22°59.5’S, 167°22.0’E, 490-515 m, with Chrysogorgiidae gen. sp. ( Calcaxonia ), 29.IX.1985, 1 ♂ 8.7 mm (MNHN- IU-2011-5955) .

ETYMOLOGY — The species is named for Enrique Macpherson who has contributed greatly to the knowledge of squat lobsters.

DISTRIBUTION„ Philippines, Solomon Islands and Norfolk Ridge; 398- 950 m.

SIZE„ Males, 8.7, 9.5 mm; females, 7.0- 10.8 mm; ovigerous females from 7.9 mm.

DESCRIPTION„ Medium-sized species. Carapace: Somewhat broader than long (0.9 × as long as broad); greatest breadth 2.0 × distance between anterolateral angles. Dorsal surface moderately convex from anterior to posterior, with slight depression between gastric and cardiac regions; sparingly with long plumose setae. Lateral margins convexly divergent posteriorly, bearing row of granulate, oblique, short ridges so as to be seen as granulose in dorsal view; anterolateral corner acuminate or very minutely spiniform, close to and distinctly posterior to level of acuminate lateral limit of orbit. Rostrum triangular, with interior angle of 30°, directed somewhat dorsally; length slightly less than half that of remaining carapace, breadth about one-third carapace breadth measured at posterior carapace margin; dorsal surface flattish. Pterygostomian flap anteriorly angular, ending in acuminate point, not produced to distinct spine; surface spineless.

Sternum: Excavated sternum with convex anterior margin between bases of Mxp1, surface with rounded ridge in midline. Sternal plastron as long as broad. Sternite 3 shallowly depressed, anterior margin moderately concave, with semi-ovate median notch flanked by obsolescent spine. Sternite 4 as broad as sternite 5; anterolateral margin anteriorly rounded, length 1.5 × that of posterolateral margin. Sternite 6 slightly broader than sternite 5, as broad as sternite 7. Sternite 5 having anterolateral margin anteriorly rounded, about as long as posterolateral margin of sternite 4.

Abdomen: Tergites smooth, with very sparse fine soft setae. Dorsal surface of somite 1 well convex from anterior to posterior. Somite 2 tergite 2.3-2.6 × broader than long; pleural lateral margins concavely divergent posteriorly, rounded on posterior terminus. Pleuron of somite 3 with blunt lateral margin. Somite 4 with rounded lateral margin. Telson half as long as broad; posterior plate distinctly emarginate on posterior margin, length 1.0-1.2 × that of anterior plate.

Eye: Small, 1.8 × longer than broad, proximally broader, bearing plumose setae proximal to cornea (very thick on paratype from Philippines), terminating in midlength of rostrum. Cornea not dilated, length about half that of remaining eyestalk.

Antennule and antenna: Ultimate article of antennular peduncle 3.3-4.0 × longer than high. Antennal peduncle overreaching eyes by full length of article 5. Article 2 laterally blunt, bearing long setae. Antennal scale about 2 × as broad as article 5, ending in midlength of article 5, bearing long plumose setae marginally. Article 4 unarmed or with tiny distomesial spine. Article 5 unarmed, 1.5 × longer than article 4, breadth more than half (0.7) height of ultimate antennular article. Flagellum of 16-19 segments reaching or slightly falling short of distal end of P1 merus.

Mxp: Mxp1 with bases broadly separated. Mxp3 with long soft setae on lateral surface. Basis without denticles on mesial ridge. Ischium with more than 30 very small, distally diminishing denticles (barely discernible under high magnification on left side in holotype) on crista dentata; flexor margin not rounded distally. Merus 2.3 × longer than ischium, flattish on mesial face, flexor margin somewhat roundly ridged, without spine. Carpus unarmed.

P1: 5-6 × longer than carapace, unarmed except for ischium bearing bluntly truncate, antero-posteriorly compressed process on distodorsal margin, sparsely setose but palm almost glabrous, fingers more setose. Merus 1.1-1.3 × longer than carapace. Carpus 1.2-1.4 × longer than merus. Palm 3-4 × longer than broad, slightly longer than or subequal to carpus in males, slightly shorter in females; fingers slightly incurved distally, crossing when closed, opposable margins without process in females, with distinct median process on movable finger in males; movable finger 0.4-0.5 × length of palm.

P2-4: Compressed mesio-laterally, with sparse long setae, unarmed on meri and carpi. Meri successively shorter posteriorly (P3 merus 0.9 × length of P2 merus, P4 merus 0.8-0.9 × length of P3 merus), equally broad on P2-4; lengthbreadth ratio, 4.1-4.3 on P2, 3.0-3.7 on P3, 3.2-3.8 on P4; P2 merus subequal to or slightly shorter than carapace, 1.1- 1.2 × longer than P2 propodus; P3 merus subequal to length of P3 propodus; P4 merus 0.9 × length of P4 propodus. Carpi subequal in length on P2 and P3 or successively slightly shorter posteriorly (P3 carpus 0.93-1.00 × length of P2 carpus, P4 carpus 0.93-0.95 × length of P3 carpus); carpus-propodus length ratio, 0.36-0.41 on P2, 0.37-0.38 on P3, 0.35-0.36 on P4. Propodi successively slightly longer posteriorly; flexor margin nearly straight, with pair of distal spines only. Dactyli subequal to carpi (dactylus-carpus length ratio, 0.8-1.0 on P2, 0.9-1.0 on P3, 1.0 on P4), about one-third length of propodi (0.33-0.35 on P2 and P3, 0.34-0.35 on P4); flexor margin straight, ending in slender spine preceded by 5-6 acute, elongate spines diminishing toward base of article (all obscured by setae on P2 and less so on P3 and P 4 in Philippine material), ultimate and penultimate spines close to each other, others rather distant from one another, not perpendicular to margin but somewhat obliquely directed, ultimate much shorter than penultimate, penultimate slightly broader than antepenultimate.

Eggs. Number of eggs carried, about 40; size, 1.00 mm × 1.16 mm - 1.44 mm × 1.27 mm.

REMARKS — The specimen from the Philippines is more setose on the body and appendages than the other specimens.

Uroptychus enriquei resembles U. onychodactylus Tirmizi, 1964 from the Maldives and U. setosidigitalis Baba, 1977 from off Midway Island, in the carapace shape, especially bearing a reduced anterolateral spine. However, these congeners can be distinguished by: sternite 3 which has a deeply excavated anterior margin lacking median notch; the P2-4 dactyli which are strongly curved and much longer relative to the propodi, with closely arranged, more numerous, shorter flexor marginal spines; and the P2-4 propodi without flexor marginal spines.

Uroptychus enriquei also resembles U. tomentosus Baba, 1974 from the east coast of New Zealand, in the carapace shape, in having sternite 4 with the anteriorly rounded anterolateral margins, in having a short antennal scale, and in the spination of the P2-4 dactyli. In U. tomentosus , however, the anterolateral spine of the carapace is distinct and the penultimate of the flexor marginal spines of P2-4 dactyli is pronounced, measuring about twice as broad as the antepenultimate, both distinctive differences from U. enriquei .

Figures

FIGURE 90 Uroptychus enriquei n. sp.,holotype,ovigerous female 10.8 mm (MNHN-IU-2011-5953).A, carapace and anterior part of abdomen, proximal part of left P1 included, dorsal. B, same, lateral. C, sternal plastron, with excavated sternum and basal parts of Mxp1. D, telson.E, right antenna,ventral.F, left Mxp3,mesial ridges of basis and ischium,setae omitted,lateral.G, same,lateral.Scale bars: A, B, H, 5 mm; C-G,1 mm.

FIGURE 91 Uroptychus enriquei n. sp., holotype, ovigerous female 10.8 mm (MNHN-IU-2011-5953). A, left P2, lateral. B, same, distal part, setae omitted, lateral.C, left P3, lateral. D, left P4, lateral. Scale bars:A, C,D, 5 mm; B,1 mm.