Uroptychus convexus Baba , 1988

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 : 140-141

Uroptychus convexus Baba, 1988

Figure 55

Uroptychus convexus Baba, 1988: 32 , fig. 12. — Poore et al. 2011: 328, pl. 6, fig. G.

TYPE MATERIAL — Holotype: Indonesia, between Cebu and Bohol, 265 m, female ( USNM 150320). [not examined].

MATERIAL EXAMINED — Indonesia, Kai Islands. KARUBAR Stn DW13, 5°26’S, 132°38’E, 417-425 m, 24.X.1991, 2 ♂ 2.5, 2.9 mm, 1 ♀ 2.7 mm (MNHN-IU-2014-16359) . – Stn DW18, 5°18’S, 133°01’E, 205-212 m, 24.X.1991, 3 ♂ 2.3-2.4 mm, 4 ♀ 2.2-2.7 mm (MNHN-IU-2014-16360).

DISTRIBUTION„ Philippines between Cebu and Bohol, and now Kai Islands; in 205- 425 m.

SIZE„ Males, 2.3-2.8 mm; females, 2.2-2.7 mm.

DIAGNOSIS — Small species. Cephalothorax relatively high. Carapace broader than long (0.8 × as long as broad), greatest breadth 1.5 × distance between anterolateral spines; dorsal surface unarmed, strongly convex from side to side and anterior to posterior, without distinct border between gastric and cardiac regions. Lateral margins weakly convexly divergent posteriorly, with 7 spines: first anterolateral, overreaching lateral orbital spine; second situated at anterior end of anterior branchial region, somewhat posterior to midpoint between first and third; third to seventh situated on posterior branchial region, posteriorly diminishing, third largest. Rostrum short, less than half length of remaining carapace, broad, equilateral triangular, with interior angle of 45°, dorsally concave; breadth less than half carapace breadth measured at posterior carapace margin. Lateral orbital spine small, very slightly anterior to level of anterolateral spine. Pterygostomian flap anteriorly angular, ending in sharp spine, unarmed on surface. Excavated sternum with convex anterior margin, surface with weak ridge in midline; sternal plastron as long as broad, lateral extremities slightly divergent posteriorly; sternite 3 moderately depressed, anterior margin gently concave, with deep, broad median notch separating obsolescent submedian spines, anterolaterally sharp angular; sternite 4 having anterolateral margin convex, anteriorly bearing a few small spines, length 1.3-1.7 × that of posterolateral margin. Anterolateral margin of sternite 5 anteriorly strongly convex, about as long as or slightly longer than posterolateral margin of sternite 4. Abdominal somite 2 tergite 2.5-2.6 × broader than long; pleuron posterolaterally rounded, lateral margins slightly convergent posteriorly; pleuron of somite 3 laterally blunt. Telson half as long as broad; posterior plate 1.0-1.4 × longer than anterior plate, emarginate on posterior margin. Eyes 2 × longer than broad, proximally broad, distally narrowed, reaching or overreaching rostral tip; cornea about half as long as remaining eyestalk or less than so. Ultimate article of antennular peduncle 2.7-2.9 × longer than high. Antennal article 2 without lateral spine; antennal scale overreaching midlength of but never reaching distal end of article 5; article 4 with ventral distomesial spine; article 5 unarmed, 1.3-1.6 × longer than article 4, breadth about half height of ultimate article of antennule; flagellum of 9-10 segments nearly or barely reaching distal end of P1 merus. Mxp1 with bases broadly separated. Mxp3 basis with a few obsolescent denticles on mesial ridge; ischium with distally rounded flexor margin, crista dentata with about 25 denticles; merus 2.0 × longer than ischium, flexor margin sharply ridged along distal two-thirds, bearing a few (usually 2) denticle-like small spines distal to midlength. P1 massive, sparsely setose; ischium with sharp curved dorsal spine, ventromesially with distinct subterminal spine; merus subequal to or slightly shorter than carapace, with a few well-developed mesial and ventral spines; carpus as long as merus; palm 1.8-2.1 × longer than broad, 1.1-1.3 × longer than carpus; fingers distally incurved, crossing when closed, opposable margins not spooned. P2-4 meri and carpi relatively thick mesio-laterally, dorsal margin with several small denticle-like spines distinct on P2, obsolescent on P3, obsolete on P4; P2 merus 0.7-0.9 × length of carapace, subequal in length and breadth to P3 merus, as long as P2 propodus; P4 merus 0.9-1.0 × length of, 0.7-0.8 × breadth of P3 merus, 0.8-0.9 × length of P4 propodus; carpi subequal, each less than half length of propodus; propodi subequal in length on P3 and P4, shorter on P2; flexor margin with pair of distal spines only; dactyli slightly shorter than or subequal to carpus on P2-4, slightly less than half as long as propodi, ending in slender spine preceded by 4-5 somewhat obliquely directed, loosely arranged spines on straight flexor margin, penultimate and antepenultimate strong, remaining proximal spines slender.

Color. A specimen in color from the Philippines was illustrated by Poore et al. (2011).

REMARKS — The specimens agree well with the type of U. convexus . Ovigerous females have not been collected.

Figures

FIGURE 55 Uroptychus convexus Baba,1988,male 2.9 mm (MNHN-IU-2014-16359).A, carapace,lateral.B, anterior part of sternal plastron.C. left P1, proximal part, ventral.Scale bar: 1 mm.