Uroptychus pilosus Baba, 1981

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 : 398-399

Uroptychus pilosus Baba, 1981

Uroptychus pilosus Baba, 1981: 126 , figs 10, 11. — Baba 2005: 53, 230 (Makassar Strait, 1600 m).

Not Uroptychus pilosus — Ahyong & Poore 2004: 71 , fig. 21 (= U. inaequalis n. sp.). — Poore 2004:226, fig. 62b.

TYPE MATERIAL — Holotype: Japan, Kumanonada off E coast of Kii Peninsula, 1120-1160 m, male ( NSMT-Cr. 6172 ). [not examined].

MATERIAL EXAMINED — Indonesia, Kai Islands. KARUBAR Stn CP20, 5°15’S, 132°59’E, 769-809 m, with Chrysogorgiidae gen. sp. ( Calcaxonia ), 25.X.1991, 2 ♂ 6.0, 6.3 mm, 1 ♀ 5.5 mm (MNHN-IU-2014-16857).

DISTRIBUTION„ Known from Japan (Kumanonada off east coast of Kii Peninsula and off southeastern Kyushu) and Makassar Strait, in 1120-1600 m, and now from Indonesia (Kai Islands), in 769- 809 m.

DIAGNOSIS — Moderate-sized species. Body covered with short soft fine setae. Carapace slightly broader than long; greatest breadth 1.7 × distance between anterolateral spines. Dorsal surface markedly convex on anterior gastric region preceded by depressed rostrum, well depressed between gastric and cardiac regions. Lateral margins with no spines, convex on branchial region; anterolateral corner rounded, with a few denticle-like or obsolescent small spines. Rostrum short triangular, with interior angle of 23°, directed slightly upwards, breadth much more than half carapace breadth at posterior carapace margin. Pterygostomian flap smooth on surface, anteriorly sharp angular, produced to distinct spine. Excavated sternum with bluntly triangular anterior margin, surface ridged in midline. Sternal plastron slightly longer than broad, lateral extremities subparallel between sternites 4-7; sternite 3 having anterior margin deeply excavated, with broad U-shaped median notch devoid of flanking spine; sternite 4 with posterolateral margin as long as anterolateral margin; anterolateral margin of sternite 5 0.7 × as long as posterolateral margin of sternite 4. Abdominal somite 2 tergite 2.2-2.3 × broader than long; pleuron posterolaterally blunt angular, lateral margin concavely divergent posteriorly; pleuron of somite 3 with blunt posterolateral terminus. Telson slightly more than half (0.53-0.57) as long as broad, posterior plate 1.5 × longer than anterior plate, distinctly emarginate on posterior margin. Eyes elongate, overreaching midlength of rostrum, lateral and mesial margins subparallel; cornea less than half length of remaining eyestalk. Ultimate article of antennule slightly more than 3 × longer than high. Antennal peduncle overreaching eye by full length of article 5; article 2 with lateral spine; antennal scale terminating in or slightly overreaching distal end of antennal article 4; article 5 relatively long (three-quarters length of article 4); flagellum of 14-15 segments not reaching distal end of P1 merus; Mxp1 with bases broadly separated. Mxp3 basis having mesial ridge proximally lobe-like, distally with 1 denticle; ischium not rounded on distal end of flexor margin, crista dentata with about 20 denticles diminishing distally; merus 2.3 × longer than ischium, relatively thick mesio-laterally, flexor margin with small spines or denticles distal to midlength. P1 slender, unarmed but ischium with short, basally broad dorsal spine; merus 1.3-1.5 × longer than carapace; carpus 1.5-1.7 × length of merus; palm slightly longer than carpus, about 8 × as long as broad; fingers ending in small incurved spine, crossing when closed; movable finger one-fourth to one-fifth length of palm, opposable margin with subtriangular proximal process. P2-4 subcylindrical; meri successively shorter posteriorly (P3 merus 0.8 × length of P2 merus, P4 merus 0.7-0.8 × length of P3 merus), equally broad on P2-4; dorsal margin with small spines on proximal third at least on P2 and P3; P2 merus about as long as or slightly shorter than carapace, slightly longer than P2 propodus; P4 merus 0.8-0.9 × length of P4 propodus; carpi successively slightly shorter posteriorly, length about one-third (0.3-0.4) that of propodus; propodi successively slightly shorter posteriorly, flexor margin concave in lateral view, with pair of terminal spines only; dactyli nearly as long as carpi on P2-4, each with 2 terminal spines of subequal size.

REMARKS — This species shares with U. inaequalis n. sp. and U. plautus n. sp. the P2-4 dactyli bearing only two terminal spines, a character rather unusual among the species of Uroptychus . Characters distinguishing U. pilosus from U. inaequalis and from U. plautus are outlined under the remarks of the latter two species (see below).