Uroptychus soyomaruae Baba 1981
Creators: name: Baba, Keiji
Publisher: name: Zenodo
Year: 2018
Subjects: Biodiversity
Taxonomy
Animalia
Arthropoda
Malacostraca
Decapoda
Chirostylidae
Uroptychus
Uroptychus soyomaruae

description: Uroptychus soyomaruae Baba, 1981
Figures 244A, B, 306D
Uroptychus soyomaruae Baba, 1981: 129, figs 12, 13. — Baba 1990: 948.
Not Uroptychus soyomaruae – Zarenkov & Khodkina 1983: 20, fig. 5 (= U. sternospinosus Tirmizi, 1964).
TYPE MATERIAL — Holotype: Japan, SE of Miyake-jima, Izu Islands, 33°55.1´N, 140°00.5´E, 860-870 m, ov. female (NSMT-Cr. 6178). [not examined].
MATERIAL EXAMINED — New Caledonia, Norfolk Ridge. HALIPRO 2 Stn BT 66, 24°45’S, 168°29’E, 885-1450 m, 19.XI.1996, 1 ov. ♀ 14.0 mm (MNHN-IU-2014-16954). French Polynesia, Marquesas Islands. MUSORSTOM 9 Stn CP1303, 8°50’S, 140°19’W, 705-794 m, with Thouarella sp. (Calcaxonia, Primnoidae), 9.IX.1997, 1 ♂ 13.0 mm, 1 ov. ♀ 12.5 mm, 2 ♀ 9.4, 14.0 mm (MNHN-IU-2014-16955). French Polynesia, Austral Islands. BEN- THAUS Stn DW2020, 22°37’S, 152°49.1’W, 920-930 m, 25.XI.2002, 1 ♀ 9.8 mm (MNHN-IU-2014-16956).
DISTRIBUTION„ Off Izu Islands (Japan), Madagascar, and now the Norfolk Ridge and French Polynesia; 705-1450 m.
SIZE„ Male, 13.0 mm; females, 9.4-14.0 mm; ovigerous females from 12.5 mm.
DIAGNOSIS„ Large species. Carapace 1.2 × longer than broad; greatest breadth 1.7 × distance between anterolateral spines. Dorsal surface with granules well developed on large specimens, less so on small specimens; gastric and cardiac regions well inflated; pair of strong gastric spines; lateral margins slightly convexly divergent posteriorly; anterolateral spine overreaching small lateral orbital spine. Rostrum narrow triangular, with interior angle of 20°; dorsal surface flattish or feebly convex from side to side and slightly upcurved. Pterygostomian flap granulose on surface, anteriorly somewhat angular, produced to distinct spine. Excavated sternum with broadly subtriangular anterior margin ending in blunt, occasionally obsolescent spine, surface with low central process; sternal plastron slightly shorter than broad, lateral extremities nearly straight divergent posteriorly. Sternite 3 having anterior margin broadly and deeply excavated, with small submedian spines; sternite 4 relatively short; anterolateral margin as long as posterolateral margin, with strong median spine directed anteroventrally, transverse ridge elevated and denticulate. Anterolateral margin of sternite 5 convexly divergent posteriorly, about half length of posterolateral margin of sternite 4. Abdomen smooth and glabrous; somite 1 tergite with antero-posteriorly convex transverse ridge; Somite 2 tergite 2.0-2.6 × broader than long; pleuron anterolaterally rounded, lateral margin somewhat convex, strongly divergent posteriorly ending in blunt tip. Pleuron of somite 3 bluntly angular on lateral end. Telson one-third to three-quarters as long as broad; posterior plate subsemicircular, length 1.6-1.9 × that of anterior plate, posterior margin convex or slightly emarginate. Eyes 1.5 × longer than broad, distally somewhat dilated, mesial margin proximal to cornea concave, lateral margin convex; cornea much more than half length of remaining eyestalk. Ultimate article of antennular peduncle 2.3-2.5 × longer than high. Antennal peduncle slender, overreaching cornea, unarmed on distal 2 articles; article 2 with tiny or obsolescent distolateral spine; antennal scale barely reaching midlength of article 5; article 5 2.0-2.3 × longer than article 4, breadth 0.3-0.4 × height of ultimate antennular article; flagellum of more than 17 segments far falling short of distal end of P1 merus. Mxp1 with bases nearly contiguous. Mxp3 basis with a few denticles, distal one distinct; ischium with flexor margin distally not rounded, crista dentata with obsolescent denticles; merus 2.6-2.8 × longer than ischium, rather thick mesio-laterally, flexor margin ridged but not well cristate; carpus unarmed. P1 slender, covered with granules; ischium with short, blunt distodorsal process, ventromesially without subterminal spine; merus 1.4-1.5 × longer than carapace, with well-developed distodorsal spine; carpus 1.3-1.4 × length of merus; palm 0.8 × length of carpus, twice length of movable finger; fingers spooned distally, not crossing. P2-4 also slender, meri and carpi subcylindrical; meri equally broad on P2-4; P2 merus slightly longer than or subequal to P3 merus, slightly shorter than carapace, 1.4-1.6 × longer than P2 propodus; P3 merus 1.2-1.3 × length of P3 propodus; P4 merus 0.9 × length of P3 merus, 1.1-1.2 × length of P4 propodus; carpi subequal, 0.7-0.8 × length of propodi on P2-4, much longer than dactyli (carpus-dactylus length ratio, 2.0-2.4 on P2, 1.8-2.8 on P3, 1.8-2.7 on P4); propodi subequal in length; flexor margin somewhat convex on distal half, with slender movable spines, terminal single, slightly distant from distal end; dactyli less than half length of propodi on P2-4, about half as long as carpi (dactylus-carpus length ratio, 0.4-0.5 on P2, 0.4-0.6 on P3 and P4); well curved, terminating in stout spine preceded by 7-12 moderately inclined spines diminishing toward base of article, often obscured by setae.
Eggs. More than 80 eggs carried; size, 1.4 mm × 1.5 mm - 1.6 mm × 1.7 mm.
Color. Ovigerous female (MNHN-IU-2014-16954) from HALIPRO 2 Stn BT 66, Norfolk Ridge: Orange red all over, including appendages.
PARASITES„ The largest female from the Marquesas Islands (MNHN-IU-2014-16955) bears a bopyrid isopod on the
left branchial region.
REMARKS — The granulose carapace, the slender pereopods, the strong lateral spine on the thoracic sternite 4, the elongate, unarmed Mxp3 merus, the short antennal scale, and the long carpi of P2-4, characteristic of the species, are also possessed by U. sternospinosus Tirmizi, 1964 and U. thermalis Baba & de Saint Laurent, 1992. However, the latter two species are distinctive in the spination of P2-4: the dactylus has the flexor margin almost smooth (though obliquely directed small spines are present on the proximal third but hardly visible under normal magnification and obscured by thick setae) except for the terminal and subterminal spines, and the propodus has the distal two flexor marginal spines remotely separated from each other (see Figures 244C, D, 263 D-G). These characters of U. sternospinosus have been confirmed by examination of the male and female syntypes (BMNH 1966.2.3.21-22) now in the collection of the Natural History Museum, London. The material reported under U. soyomaruae by Zarenkov & Khodkina (1983) from the Marcus-Necker Rise is in all probability referable to U. sternospinosus.
description: Published as part of Baba, Keiji, 2018, Chirostylidae of the Western and Central Pacific: Uroptychus and a new genus (Crustacea: Decapoda: Anomura), pp. 1-612 in Mémoires du Muséum national d'Histoire naturelle 212 on pages 487-489, DOI: 10.5281/zenodo.3760976