Uroptychus toka Schnabel, 2009

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 : 523-526

Uroptychus toka Schnabel, 2009

Figures 264 , 265

Uroptychus toka Schnabel, 2009: 568 , fig. 14.

TYPE MATERIAL — Holotype: New Zealand, L’Esperance Rock , Kermadec Ridge, 33°02.59’S, 179°34.60’W, 350-490 m, ov. female ( NMNZ Cr. 012090 ). [not examined].

MATERIAL EXAMINED — New Caledonia, Loyalty Ridge. MUSORSTOM 6 Stn DW478, 21°08.96’S, 167°54.28’E, 400 m, 22.II.1989, 1 ♀ 3.7 mm (MNHN-IU-2014-16989) . New Caledonia, Norfolk Ridge. CHALCAL 2 Stn DW82, 23°13.68’S, 168°04.27’E, 304 m, 31.X.1986, 1 ♂ 2.6 mm ( MNHN- IU-2014-16991) . NORFOLK 1 Stn DW1657, 23°28’S, 167°52’E, 305-332 m, 19.VI.2001, 1 ♀ 2.9 mm (MNHN-IU-2014-16992) . NORFOLK 2 Stn CP2048, 23°43.82’S, 168°16.24’E, 380-389 m, unidentified host, 24.X.2003, 2 ov. ♀ 2.7, 2.8 mm (MNHN-IU-2014-16993) . Vanuatu, Monts Gemini. GEMINI Stn DW51, 20°58’S, 170°04’E, 450- 360 m, 04.VII.1989, 1 ♀ 2.9 mm (MNHN-IU-2014-16990) .

DISTRIBUTION„ Kermadec Ridge in 350-490 m, and now south of Vanuatu, Loyalty Ridge and Norfolk Ridge, in 304- 450 m.

SIZE„ Male, 2.6 mm; females, 2.8-3.7 mm; ovigerous females from 2.7 mm.

DESCRIPTION — Small species. Body and appendages very setose. Carapace: 0.85-0.95 × as long as broad; greatest breadth 1.7 × distance between anterolateral spines. Dorsal surface with long soft setae particularly numerous on branchial region, denticle-like small spines on hepatic and epigastric regions, and distinct depression bordering gastric and cardiac regions; gastric region slightly inflated, anteriorly elevated from level of rostrum. Lateral margins convex medially or on posterior third, with row of short, oblique, elevated setiferous ridges usually weak, often distinct; ridged along posterior third; anterolateral spine small, subequal to and very close to lateral orbital spine (in dorsal view, nearly contiguous at base). Rostrum nearly horizontal, triangular with interior angle of 35°, anteriorly ending in blunt tip; length 0.4 × that of remaining carapace, breadth half carapace breadth at posterior carapace margin; dorsal surface concave. Lateral orbital spine larger than anterolateral spine. Pterygostomian flap equally high on anterior and posterior halves, surface with scattered denticles and long setae, and row of tubercle-like small spines below linea anomurica; anterior margin angular, produced to small spine.

Sternum: Excavated sternum with somewhat rounded or bluntly triangular anterior margin, surface ridged in midline. Sternal plastron slightly longer than broad; lateral extremities subparallel between sternites 4 and 7. Sternite 3 weakly depressed; anterior margin shallowly emarginate, representing broad V-shape, with narrow U-shaped median sinus flanked by obsolescent spine, lateral end blunt. Sternite 4 having anterolateral margin nearly straight or slightly convex, anterior end blunt angular or rounded; posterolateral margin as long as anterolateral margin. Anterolateral margins of sternite 5 somewhat convex anteriorly, subparallel, slightly more than half as long as posterolateral margin of sternite 4.

Abdomen: Sparsely or thickly setose. Somite 2 tergite 2.2 × broader than long; pleuron posterolaterally rounded, lateral margin nearly straight or feebly concave. Pleuron of somite 3 blunt on lateral terminus. Telson about half as long as broad; posterior plate distinctly emarginate on posterior margin, slightly (1.1 x) longer than anterior plate.

Eye: Slightly falling short of apex of rostrum, 1.7 × longer than broad; mesial and lateral margins slightly convex or subparallel. Cornea not dilated, length half that of remaining eyestalk.

Antennule and antenna: Ultimate article of antennular peduncle 2.6-2.7 × longer than high. Antennal peduncle reaching apex of rostrum. Article 2 with strong distolateral spine. Antennal scale 1.5 × broader than article 5, slightly or moderately overreaching distal end of article 4, not reaching midlength of article 5. Article 4 distomesially produced to short spine. Article 5 unarmed, length 1.4 × that of article 4, breadth half height of antennular ultimate article. Flagellum of 10-11 segments not reaching distal end of P1 merus.

Mxp: Mxp1 with bases remotely separated. Mxp3 with long setae on lateral surface. Basis without denticles on mesial ridge. Ischium with obsolescent denticles on crista dentata, flexor margin rounded at distal end. Merus unarmed, twice as long as ischium, broad relative to length, well compressed and crested along flexor margin. Carpus unarmed.

P1: 5.4-5.8 × longer than carapace in females (missing in male); relatively slender, smooth with long setae. Ischium with short dorsal spine, ventromesially unarmed. Merus 1.3-1.4 × longer than carapace. Carpus 1.2-1.3 × longer than merus, nearly as long as or slightly longer than palm. Palm 3.9-4.8 × longer than broad, slightly broader than carpus. Fingers ventrally curved, ending in slightly incurved spine, slightly crossing when closed; movable finger 0.4-0.5 × length of palm, opposable margin with 2 low prominences in proximal half, that of fixed finger gently concave.

P2-4: With long soft setae. Meri successively shorter posteriorly (P3 merus 0.8-0.9 × length of P2 merus, P4 merus 0.9 × length of P3 merus), equally broad on P2-4; rather thick mesio-laterally and unarmed; length-breadth ratio, 3.2- 4.1 on P2, 3.1-3.7 on P3, 2.6-3.3 on P4; P2 merus 0.8-0.9 × length of carapace, about as long as or slightly longer than P2 propodus; P3 merus 0.8 × length of P3 propodus; P4 merus 0.7-0.8 × length of P4 propodus. Carpi subequal, relatively short, 0.3-0.4 × length of propodus on P2 and P3, 0.3 × on P4. Propodi successively longer posteriorly; flexor margin slightly curving, with pair of terminal spines only. Dactyli subequal, 1.3 (P2 and P3)-1.4 × (P4) longer than carpi, slightly less than half (0.44-0.49 on P2, 0.45-0.49 on P3, 0.41-0.47 on P4) length of propodi; flexor margin straight, with 6 or 7 loosely arranged spines nearly perpendicular to margin except for ultimate spine; ultimate very small and slender, close to penultimate; penultimate prominent; antepenultimate half as broad as penultimate, subequal to fourth; remainder smaller, diminishing toward base of article.

Eggs. Number of eggs carried, 4-5; size, 0.97 mm × 1.08 mm - 1.06 mm × 1.18 mm.

REMARKS„ The specimen from NORFOLK 1 Stn DW1657 (MNHN-IU-2014-16992) is much more densely setose on the body and appendages than the other specimens. Uroptychus toka resembles U. volsmar n. sp. more closely than U. bertrandi n. sp., U. sarahae , U. rutua , in having the anterolateral spine of the carapace contiguous at base with the lateral orbital spine when viewed from dorsal side. The relationships with U. volsmar are discussed under that species (see below). For the relationships between the other congeners, see under the remarks of U. bertrandi and U. sarahae (see above).

Figures

FIGURE 264 Uroptychus toka Schnabel,2009,female 3.7 mm (MNHN-IU-2014-16989).A, carapace and anterior part of abdomen, proximal part of right P1 included, dorsal. B, same, lateral.C, sternal plastron, with excavated sternum and basal parts of Mxp1. D, telson. E, left antenna, ventral.F, left Mxp3, ventral.G, same, merus and carpus,lateral. Scale bars:1 mm.

FIGURE 265 Uroptychus toka Schnabel,2009,female 3.7 mm (MNHN-IU-2014-16989).A, right P1, dorsal.B, left P2,lateral.C, same,distal part,setae omitted,lateral. D, left P3,setae omitted,lateral. E, left P4,lateral. Scale bars:1 mm.