Uroptychus gracilimanus Alcock 1901
Creators: name: Baba, Keiji
Publisher: name: Zenodo
Year: 2018
Subjects: Biodiversity
Taxonomy
Animalia
Arthropoda
Malacostraca
Decapoda
Chirostylidae
Uroptychus
Uroptychus gracilimanus

description: Uroptychus gracilimanus (Henderson, 1885)
Figures 98-100
Diptychus gracilimanus Henderson, 1885: 420.
Uroptychus gracilimanus — Henderson 1888: 181, pl. 21, figus 5, 5a, 5b. — Tirmizi 1964: 392, figs 6-9. — Baba 1990: fig. 8a.
Not U. gracilimanus Baba 1969: 45, figs 3, 4; 1988: 35. — Baba et al. 2009: 44, figs 36-37; 2005: 36 (= U. dejouanneti n. sp.). — Baba 1990: 941, figs 8b (= undescribed species).— Doflein & Balss 1913: 134 (part) (1 ov. ♀ from Valdivia St. 250 = U.remotispinatus Baba & Tirmizi, 1979; 1 ♂ from Valdivia St. 245 = undescribed species). — Ahyong & Poore 2004: 40, fig. 10 (= U. nigricapillis Alcock, 1901). — Poore et al. 2008: 17 (fig.) (= U.taylorae McCallum & Poore, 2013).
Identification questioned:
Uroptychus gracilimanus — Parisi 1917: 3.
Uroptychus gracilimanus var. bidentatus — Doflein & Balss, 1913: 20.
TYPE MATERIAL — Holotype: Australia, Port Jackson, CHALLENGER Stn 164, 410 fms (750 m), ov. female (BMNH 1888:33). [examined].
MATERIAL EXAMINED — Australia, Port Jackson. CHALLENGER Stn 164, 410 fms (750 m), 1 ov. ♀ 7.9 mm, holotype (BMNH 1888: 33). Solomon Islands. SALOMON 1 Stn CP1792, 9°15.4’S, 160°08.9’E, 477-505 m, 30.IX.2001, 1 ♂ 5.4 mm, 3 ov. ♀ 6.2-7.6 mm, 1 ♀ 7.0 mm (MNHN- IU-2013-8542). – Stn CP1793, 9°13.4’S, 160°07.8’E, 505-510 m, 30.IX.2001, 2 ♂ 7.1, 7.4 mm, 1 ov. ♀ 6.5 mm (MNHN-IU-2013-8543). – Stn CP1794, 9°16.1’S, 160°07.7’E, 494-504 m, 30.IX.2001, 1 ov. ♀ 7.2 mm (MNHN-IU-2013-8544). – Stn CP1858, 9°37.0’S, 160°41.7’E, 435-461 m, 7.X.2001, 1 ♂ 6.0 mm (MNHN-IU-2011-5914), 1 ♂ 6.1 mm (MNHN-IU-2011-5915). – No data, 1 ♂ 6.7 mm (MNHN-IU-2013-8545). SALOMON 2 Stn CP2176, 9°09.4’S, 158°59.2’E, 600-875 m, 21.X.2004, 1 ♂ 4.9 mm, 1 ♀ 5.7 mm (MNHN-IU-2013-8546). – Stn CP2213,7°38.7’ S, 157°42.9’E, 495- 650 m, 26.X.2004, 1 ♂ 7.1 mm, 1 ov. ♀ 7.2 mm (MNHN-IU-2013-8547). – Stn DW2238, 06°53’S, 156°21’E, 470-443 m, 30.X.2004, 1 ov. ♀ 6.2 mm (MNHN-IU-2013-8548). – Stn CP2245, 7°43.1’S, 156°26.0’E, 582-609 m, 1.XI.2004, 1 ov. ♀ 6.1 mm (MNHN-IU-2013-8549). – Stn CP2246, 7°42.6’S, 156°24.6’E, 664-682 m, 1.XI.2004, 1 ov. ♀ 6.7 mm, 1 ♀ 4.9 mm (MNHN-IU-2013-8550). – Stn CP2247, 7°44.9’ S, 156°24.7’E, 686-690 m, 1.XI.2004, 2 ♂ 5.7, 6.8 mm, 3 ov. ♀ 5.4-6.2 mm (MNHN-IU-2013-8551). – Stn CP2253, 7°26.5’S, 156°15.0’E, 1200-1218 m, 2.XI.2004, 1 ov. ♀ 7.5 mm (MNHN- IU-2013-8552). – Stn CP2267, 7°48.0’S, 156°52.0’E, 590-600 m, 4.XI.2004, 1 ♂ 7.1 mm (MNHN-IU-2013-8553). – Stn CP2269, 7°45.1’S, 156°56.3’E, 768-890 m, 4.XI.2004, 1 ♂ 6.3 mm, 1 ov. ♀ 5.5 mm (MNHN-IU-2013-8554). – Stn CP2289, 08°36’S, 157°28’E, 627-623 m, 07.XI.2004, 1 ♂ 6.4 mm, 1 ♀ 5.4 mm (MNHN-IU-2013-8555). Vanuatu. MUSORSTOM 8 Stn CP993, 18°48.78’S, 168°54.04’E, 780-783 m, 24.IX.1994, 1 ov. ♀ 6.5 mm, 2 ♀ 6.6, 8.0 mm (MNHN-IU-2013-8556). – Stn DW1064, 16°16’S, 167°21’E, 459-459 m, 2.X.1994, 1 ♂ 6.0 mm (MNHN-IU-2011-5913). New Caledonia, Loyalty Ridge. BATHUS 3 Stn DW786, 23°54.46’S, 169°49.15’E,699-715 m, 25.XI.1993, 1 ♂ 4.9 mm (MNHN-IU-2011-5911).). New Caledonia, Isle of Pines. BATHUS 2 CP738, 23°02’S, 166°56’E, 558-647 m, 13.V.1993, 1 ♀ 5.1 mm (MNHN-IU-2011-5912). New Caledonia, Norfolk Ridge. BATHUS 3 Stn CP831,23°04’S, 166°56’E,650-658 m, 30.XI.1993, 1 ov.♀ 6.7 mm (MNHN-IU-2013-8557). – Stn CP832, 23°03’S,166°54’E, 650-659 m, 30.XI.1993, 2 ov. ♀ 7.0, 7.5 mm (MNHN-IU-2013-8558). – Stn CC848, 23°02’S, 166°53’E, 680-700 m, 1.XII.1993, 1 ♂ 6.9 mm (MNHN-IU-2013-8559). HALIPRO 1 Stn CH 872, 23°02’S, 166°52’E, 620-700 m, 30.III.1994, 1 ov.♀ 7.4 mm (MNHN-IU-2013-8560). – Stn CH 873, 23°02’S, 166°54’E,640-680 m, 30.III.1994, 1 ♀ 6.0 mm (MNHN-IU-2013-8561).
DISTRIBUTION„ Port Jackson and Zanzibar, 421-750 m; and now Solomon Islands, Vanuatu, Isle of Pines, and Norfolk Ridge; in 435-1218 m.
SIZE„ Males, 4.9-7.4 mm; females, 4.9-7.9 mm; ovigerous females from 5.4 mm.
DESCRIPTION„ Medium-sized species. Carapace: As long as broad; greatest breadth 1.6-1.7 × distance between anterolateral spines. Dorsal surface smooth, glabrous and unarmed, anteriorly inflated in profile, with or without faint depression between gastric and cardiac regions. Lateral margins convexly divergent posteriorly, with row of obsolescent denticulate short ridges along anterior half; ridged along posterior half; anterolateral spine small, varying from barely to fully reaching tiny lateral orbital spine where present, situated distinctly posterior to position of that spine. Rostrum triangular with interior angle of 25-30°, horizontal or directed slightly ventrally; length 0.3-0.4 × postorbital carapace length, breadth much less than half carapace breadth measured at posterior carapace margin; lateral margins often concave; dorsal surface slightly concave at base. Lateral orbital spine small, often obsolescent or absent. Pterygostomian flap anteriorly roundish, bearing very small spine, surface smooth.
Sternum: Excavated sternum anteriorly broad triangular, ending in sharp spine, surface with spine in center. Sternal plastron about as long as broad, lateral extremities between sternites 4 and 7 straight divergent posteriorly. Sternite 3 moderately depressed, with well excavated anterior margin bearing 2 small submedian spines flanking narrow, shallow sinus. Sternite 4 having anterolateral margin convex with a few small spines on anterior half (anterior 2 often pronounced and others obsolescent), about 1.5 × length of posterolateral margin. Anterolateral margins of sternite 5 moderately convexly divergent posteriorly or with lateral margins nearly subparallel, slightly longer than posterolateral margin of sternite 4.
Abdomen: Tergites smooth and glabrous. Somite 1 dorsally convex from anterior to posterior, without transverse ridge. Somite 2 tergite 2.0-2.5 × broader than long; pleuron posterolaterally rounded, lateral margin somewhat concavely divergent posteriorly. Pleuron of somite 3 laterally blunt. Telson about half as long as broad; posterior plate distinctly or feebly emarginate, feebly concave or feebly convex on posterior margin, length 1.5-2.0 × that of anterior plate.
Eye: Short relative to breadth (about 1.6 × longer than broad), slightly concave on mesial margin, slightly convex on lateral margin, ending in between midlength and point four-fifths of rostrum. Cornea not dilated, about half length of remaining eyestalk.
Antennule and antenna: Ultimate article of antennular peduncle 2.1-2.5 × longer than high. Antennal peduncle overreaching cornea, barely reaching rostral tip. Article 2 with tiny lateral spine. Antennal scale 1.3-1.4 × broader than article 5, terminating in or overreaching midlength of article 5, never reaching its distal end. Distal 2 articles unarmed; article 5 2.0-2.5 × longer than article 4, breadth one-third to half height of ultimate antennular article. Flagellum of 16-20 segments nearly or barely reaching distal end of P1 merus.
Mxp: Mxp1 with bases close to each other. Mxp3 spineless on merus and carpus. Basis with 3 or 4 denticles on mesial ridge. Ischium with 20-30 denticles on crista dentata, flexor margin not rounded distally. Merus 2.3 × longer than ischium, relatively thick mesio-laterally, flexor margin sharply ridged. Carpus unarmed.
P1: Slender (male palm in large specimens massive, broader than distance between anterolateral spines of carapace), sparsely setose on fingers, glabrous elsewhere; length 4.9-5.9 × (males), 4.1-7.5 × (females) that of carapace. Ischium with basally broad, low and blunt dorsal spine often obsolescent; ventrally unarmed. Merus 1.2-1.3 × longer than carapace. Carpus 1.3-1.5 × longer than merus. Palm with length-breadth ratios of 2.1-4.0 (males; slender in small specimens) and 3.7-5.0 (females), length 0.7-0.9 × that of carpus. Fingers proportionately broad, ending in incurved tips, feebly crossing; movable finger 0.5-0.7 × (males), 0.4-0.6 × (females) length of palm; opposable margin of movable finger with broad proximal process low in females, high and 2-toothed in males.
P2-4: Slender. Meri successively shorter posteriorly (P3 merus 0.9 × length of P2 merus, P4 merus 0.9 × length of P3 merus), breadths subequal on P2-4 or slightly narrower on P2 than on P3; length-breadth ratio, 5.6-6.9 on P2, 5.0-6.5 on P3, 4.0-5.4 on P4; dorsal and ventral margins unarmed; P2 merus 0.8-0.9 × length of carapace, 1.1-1.3 × length of P2 propodus; P3 merus subequal to length of P3 propodus; P4 merus 0.8-0.9 × length of P4 propodus. Carpi subequal or successively shorter posteriorly; carpus-propodus length ratio, 0.5-0.6 on P2, 0.4-0.5 on P3, 0.4 on P4. Propodi subequal or successively slightly longer posteriorly; flexor margin nearly straight, with 6-9 long spines on distal two-thirds to fourfifths on P2, 5-8 spines more distal on P3-4, terminal spine single, located very close to distal end and mesial to flexor midline. Dactyli curving at middle, length 0.4-0.5 × that of propodus on P2-4; dactylus-carpus length ratio, 0.8-0.9 (rarely 1.0) on P2, 0.9-1.0 on P3 and P4; flexor margin with 8-10 sharp spines diminishing toward base of article, ultimate spine more slender than penultimate spine.
Eggs. Up to about 40 eggs carried; size, 1.10 mm × 1.20 mm - 1.33 mm × 1.41 mm. Holotype with 30 eggs, 1.7 mm in diameter.
REMARKS — The holotype has all the P2-4 detached from the body, with the dactyli broken at the tip. Material in the Australian Museum collected from NE of Wollongong and E of Broken Bay, the vicinity of Port Jackson, was examined at my request by Shane Ahyong. His illustrations show that the ultimate of the flexor spines of the dactyli is more slender than the penultimate, a consistent character in all the above-listed material that separates the species from U. dejouanneti n. sp. Uroptychus dejouanneti is described based upon material from Indonesia (see above). It has the ultimate and penultimate spines subequal, and is identical with the previously reported material under G. gracilimanus from the East China Sea (Baba 1969), Taiwan (Baba et al. 2009), Indonesia in the Molucca Sea (Baba 1988), and the Philippines off Zamboanga (Baba, 2005).
Examination of the John Murray material from Zanzibar (Tirmizi 1964) shows that it has been correctly identified, perfectly fitting the species definition herein proposed. The specimens from Madagascar reported by Baba (1990) represent an undescribed species and have been removed from the synonymy and part of the Valdivia collection has been transferred to U. remotispinatus (see Baba 2005: 36).
Uroptychus gracilimanus resembles U. brevisquamatus Baba, 1988 in the carapace shape, from which it is readily differentiated by the following: the P2-4 propodi bear a single instead of paired terminal spines on the flexor margin, the flexor margins of the P2-4 dactyli bear elongate triangular instead of very short spines; and the antennal article 2 bears a tiny instead of strong lateral spine.
All the material of U. gracilimanus reported by Ahyong & Poore (2004) from southeastern Australia and Tasmania agrees well with U. nigricapillis Alcock, 1901.
According to molecular data provided by L. Corbari (personal comm.), the two specimens from Salomon 1 Stn CP1858 (MNHN-IU-2011-5914 and 5915; divergence of 5.7 %) are different from each other at a specific level, and one of these is also genetically different from the other specimens from the Solomon Islands, Vanuatu, Loyalty Ridge and Isle of Pines. However, I find no clear morphological differences between them.
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 220-225, DOI: 10.5281/zenodo.3760976