Uroptychus crassipes Van Dam, 1939

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 : 146-148

Uroptychus crassipes Van Dam, 1939

Figure 58

Uroptychus crassipes Van Dam, 1939: 392 , fig. 1. — Baba 1988: 35. — Baba 2005: 35, 225. — Baba et al. 2008: 31.

TYPE MATERIAL — Holotype: Indonesia, Kei Islands , 5°29’S, 132°27’E, 290 m, male ( ZMUC-CRU 6124 ). [not examined].

MATERIAL EXAMINED — Indonesia, Kai Islands. KARUBAR Stn CP09, 5°23’S, 132°29’E, 368-389 m, 23.X.1991, 5 ♂ 4.0-8.5 mm, 4 ov. ♀ 6.1- 9.0 mm, 2 ♀ 5.0, 6.0 mm (MNHN-IU-2014-16363) . – Stn CP16, 5°17’S, 132°50’E, 315-349 m, 24.X.1991, 1 ♂ 7.2 mm, 1 ov. ♀ 6.8 mm (MNHN- IU-2014-16364) . Tanimbar Islands. KARUBAR Stn CP69,8°42’S, 131°53’E,356-368 m, 2.XI.1991, 2 ♂ 5.7,6.1 mm, 1 ov.♀ 6.6 mm, 1 ♀ 7.0 mm (MNHN- IU-2014-16365) . – Stn CP83,09°23’S,131°00’E,285-297 m, 4.XI.1991, 1 ov.♀ 4.7 mm (MNHN-IU-2014-16366) . Philippines. MUSORSTOM 2 Stn CP36, 13°31’N, 121°24’E, 569-595 m, 24.XI.1980,3 ov. ♀ 4.9-5.4 mm (MNHN-IU-2014-16367) . – Stn CP46, 13°27’N, 122°18’E,445-520 m, 26.XI.1980, 2 ♀ 3.8, 5.3 mm (MNHN-IU-2014-16368) .

DISTRIBUTION„ Kai and Tanimbar Islands ( Indonesia), and off eastern Mindoro ( Philippines); 285- 595 m.

SIZE„ Males, 4.0- 8.5 mm, females, 3.8-9.0 mm; ovigerous females from 4.7 mm.

DIAGNOSIS — Medium-sized species. Body and pereopods covered with fine setae, especially long on pereopods. Carapace 0.8 × as long as broad, greatest breadth 1.7 × distance between anterolateral spines; lateral margins convex, bearing 7 spines: first anterolateral, relatively small, slightly overreaching lateral orbital spine; second and third much smaller than first; third occasionally obsolete; fourth to seven acute, situated on branchial region. Rostrum sharp triangular, with interior angle of 20-25°, breadth less than half carapace breadth measured at posterior carapace margin; dorsal surface concave, lateral margin with small subapical spine on each side. Pterygostomian flap anteriorly angular, produced to sharp spine. Excavated sternum having anterior margin convex, surface with low longitudinal ridge in midline; sternal plastron slightly shorter than broad, sternites successively broader posteriorly; sternite 3 strongly depressed, anterior margin shallowly concave, with pair of submedian spines separated by narrow or relatively broad notch; sternite 4 with nearly straight or slightly concave anterolateral margin about 1.5 × longer than posterolateral margin. Anterolateral margin of sternite 5 anteriorly produced bluntly or roundly, length distinctly more than that of posterolateral margin of sternite 4. Abdominal somite 1 with antero-posteriorly convex setiferous transverse ridge. Somite 2 tergite 2.6 × broader than long; pleuron posterolaterally blunt angular, lateral margin slightly concave and somewhat divergent posteriorly. Pleuron of somite 3 bluntly angular on posterolateral margin. Telson about half as long as broad; posterior plate as long as anterior plate, feebly concave or moderately emarginate on posterior margin. Eyes elongate (2.0-2.6 × longer than broad), slightly overreaching midlength of rostrum, mesial and lateral margins subparallel; cornea not dilated, length more than half that of remaining eyestalk. Ultimate article of antennular peduncle 3.7-4.0 × longer than high. Antennal article 2 with small distolateral spine; antennal scale overreaching distal end of article 5, reaching subapical spine of rostrum; articles 4 and 5 each with strong distomesial spine, article 5 1.5-1.7 × longer than article 4, breadth 0.7-0.8 × height of ultimate article of antennule, flagellum of 20-24 segments distinctly overreaching distal end of P1 merus. Mxp1 with bases broadly separated. Mxp3 basis having convex mesial ridge without denticle; ischium with distally rounded flexor margin, crista dentata with more than 30 denticles; merus and carpus each with distinct distolateral spine; merus 1.9 × longer than ischium, flexor margin with a few small spines on distal third; carpus with distolateral spine. P1 massive, with short transverse ridges supporting setae; ischium with 1 strong dorsal and 1 ventromesial subterminal spine; merus as long as or slightly longer than carapace, with terminal (including 2 dorsal terminal) and mesial marginal spines; carpus with terminal (including 2 dorsal terminal) spines, length subequal to that of merus and 0.8-0.9 × that of palm; palm 2.1-2.6 × longer than broad; fingers 0.5-0.6 × length of palm, distally crossing, opposable margins sinuous, proximal process of movable finger fitting to between 2 low eminences of fixed finger. P2-4 with setiferous short ridges like those on P1, meri somewhat compressed mesio-laterally, ventrolaterally bearing distolateral spine; successively slightly shorter posteriorly or often subequal on P2-3; P2 merus 0.7-0.8 × length of carapace, slightly longer than P2 propodus; P4 merus 0.8-0.9 × as long as and 0.9 × as broad as P3 merus, 0.8 × length of P4 propodus; carpi successively slightly shorter posteriorly, half as long as propodus on P2, nearly half or slightly less than half as long on P3, much less than so on P4; extensor margin with terminal spine accompanied with another small spine lateral to it; propodal flexor margin with pair of terminal spines preceded by 1-5 spines on P2, 0-4 on P3 and P4; dactyli longer than carpi (dactylus-carpus length ratio, 1.1-1.3 on P2, 1.2- 1.5 on P3, 1.4-1.5 on P4), flexor margin with obliquely directed spines close to one another and obscured by dense setae, penultimate prominent, 2 × as broad as antepenultimate, remainder slender, ultimate subequal to antepenultimate.

Eggs. Up to about 60 eggs carried; size, 0.86 mm × 0.98 mm - 0.85 mm × 1.00 m.

REMARKS„ The specimens from the Kai Islands bear setiferous short ridges on the carapace dorsal surface so as to resemble U. micrommatus n. sp. that was taken together at KARUBAR Station CP09. However, the following characteristics are distinctive of U. crassipes : the rostrum is strongly excavated along the dorsal midline, bearing a distinct subterminal spine on each side; the anterior margin of sternite 3 has a pair of distinct submedian spines; the P1 ischium bears a stronger subterminal spine on the ventromesial margin, and the merus and carpus bear terminal spines on the dorsal side; and the eyes are subcylindrical, elongate and uniform in breadth. Uroptychus crassipes also resembles U. occultispinatus Baba, 1988 , and U. worrorra McCallum & Poore 2013 . Uroptychus crassipes differs from U. occultispinatus in having small but distinct spines on the distodorsal margins of the P1 merus and carpus, in having sharper spines on the branchial lateral margin, and in having a well-developed subterminal spine on the ventromesial margin of the P1 ischium. Uroptychus worrorra is characterized by having five branchial lateral spines (four in U. crassipes ), smooth lateral rostral margins (bearing a subapical spine in U. crassipes ), P1 slender rather than massive, with the carpus longer than the palm (shorter in U. crassipes ), and the P2 merus bearing a row of small dorsal spines (unarmed in U. crassipes ).

Figures

FIGURE 58 Uroptychus crassipes Van Dam,1939;A, B, male 6.1 mm (MNHN-IU-2014-16365);C-F, I, male 8.5 mm (MNHN-IU-2014-16363); G, H, male 7.2 mm (MNHN-IU-2014-16363).A, carapace and anterior part of abdomen,dorsal.B, same,setae omitted,lateral. C, anterior part of sternal plastron.D, left antenna,ventral.E, right Mxp3,setae omitted,ventral.F, same,lateral.G,left P1, setae (and supporting ridges) omitted, dorsal. H, same, proximal part, setae omitted, ventral. I, left P2, distal part, setae omitted, lateral. Scale bars: 1 mm.