Uroptychus nigricapillis Alcock, 1901

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 : 341-356

Uroptychus nigricapillis Alcock, 1901

Figures 162-173

Uroptychus nigricapillis Alcock, 1901: 283 , pl. 3, fig. 3. — Alcock & McArdle 1902: pl. 56, fig. 3. — Van Dam 1933: 26; 1940: 98, fig. 2. — Baba 1981: 116, fig. 4; 1988: 40; 1990: 947 (part). — Baba 2005: 50 (part). — Baba et al. 2008: 37. — Baba et al. 2009: 50 (part), figs 41, 43. — Poore et al. 2011: 329, pl. 7, fig. E.

Uroptychus gracilimanus — Ahyong & Poore 2004: 40 , fig. 10 (not U.gracilimanus Alcock, 1901 ).

Not Uroptychus nigricapillis — Laurie 1926: 123 (= U. longioculus Baba, 1990 ). — Tirmizi 1964: 390, figs 4, 5. — Baba 2005: 50 (part) (new species). — Ahyong & Baba 2004: 60 , fig. 2. — Baba et al. 2009: 50 (part), fig. 42. — Poore et al. 2011: 329, pl. 7, fig. F (new species).

TYPE MATERIAL — Holotype: Andaman Sea , 669 fms (1224 m), female, ZSI 3443/10 ). [not examined] .

MATERIAL EXAMINED — Solomon Islands. SALOMON 1 Stn CP1807, 09°42’S, 160°53’E, 1077-1135 m, 02.X.2001, 1 ♂ 10.8 mm ( MNHN- IU-2014-16817). SALOMON 2 Stn CP2182, 8°47.0’S, 159°37.9’E, 762-1060 m, 22.X.2004, 1 ♂ 8.3 mm (MNHN-IU-2014-16818). – Stn CP2230, 6°27.8’S, 156°24.3’ E, 837-945 m, 29.X.2004, 1 ♀ 9.2 mm (MNHN-IU-2013-12298) . – Stn CP2260, 8°03.5’S, 156°54.5’E, 399-427 m, 3.XI.2004, 1 ♂ 7.5 mm, 1 ♀ 7.8 mm (MNHN-IU-2014-16819) .– Stn CP2261, 8°01.9’S, 156°54.1’E, 433-470 m, 3.XI.2004, 1 ♀ 9.6 mm (MNHN-IU-2014-16820). Wallis and Futuna Islands. MUSORSTOM 7 Stn CP564, 11°46’S, 178°27’W, 1015-1020 m, with Chrysogorgia sp.( Calcaxonia , Chrysogorgiidae ), 20.V.1992, 3 ♂ 7.9-8.3 mm, 2 ov. ♀ 8.7-9.1 mm, 4 ♀ 7.1-8.8 mm (MNHN-IU-2014-16821) .– Stn CP567, 11°47’S, 178°27’W, 1010-1020 m, 20.V.1992, 1 ♂ 6.7 mm, 1 ov. ♀ 7.8 mm, 4 ♀ 7.0- 9.4 mm (MNHN-IU-2014-16822), 1 ov. 9.0 mm (MNHN-IU-2013-12297). Vanuatu. MUSORSTOM 8 Stn CP990, 18°51.63’S, 168°50.98’E, 980- 990 m, 24.IX.1994, 1 ov. ♀ 8.0 mm (MNHN-IU-2014-16823) . – Stn CP1008, 18°53.29’S, 168°52.65’E, 919-1000 m, 25.IX.1994, 1 ♂ 8.8 mm ( MNHN- IU-2014-16824) .– Stn CP1037, 18°03.70’S, 168°54.40’ E, 1058-1086 m, 29.IX.1994 ,1 ov. ♀ 8.6 mm, 1 ♀ 9.8 mm (MNHN-IU-2014-16825). – Stn CP1125, 15°57.63’S, 166°38.43’E, 1160-1220 m, 10.X.1994, 2 ♂ 6.4, 7.3 mm (MNHN-IU-2014-16826). – Stn CP1129, 16°00.73’S, 166°39.94’E, 1014-1050 m, 10.X.1994, 6 ♂ 5.0- 8.9 mm, 3 ov. ♀ 7.1-8.9 mm, 1 ♀ 6.6 mm (MNHN-IU-2010-5420,MNHN-IU-2013-12296, MNHN-IU-2014-16827). New Caledonia, Chesterfield Islands. MUSORSTOM 5 Stn CP324, 21°15.01’S, 157°51.33’E, 970 m, 14.X.1986, 1 ♂ 8.3 mm, 1 ov. ♀ 8.2 mm (MNHN-IU-2010-5421). New Caledonia. BIOCAL Stn CP55, 23°20’S, 167°30’E, 1160-1175 m, 1.IX.1985, 1 ov. ♀ 7.7 mm (MNHN-IU-2014-16828) . – Stn CP61, 24°11’S, 167°32’E, 1070 m, 2.IX.1985, 2 ov. ♀ 9.2, 11.0 mm (MNHN-IU-2014-16829).

DISTRIBUTION„ Western Indian Ocean ( Mozambique Channel, Zanzibar, off Kenya, South Arabian coast, Madagascar and Maldives), Andaman Sea, west of Makassar, Java Sea, Flores Sea off southern Sulawesi, between Siquijor and Bohol, South China Sea, Taiwan and Japan (southeastern Kyushu), in [66] 450-1939 m, and now Solomon Islands, Wallis and Futuna Islands, Vanuatu, Chesterfield Islands and New Caledonia, in 399-1220 m.

SIZE„ Males, 5.0- 10.8 mm; females, 6.6-11.0 mm; ovigerous females from 7.1 mm.

DESCRIPTION„ Medium-sized species. Carapace: 1.1-1.2 × longer than broad; greatest breadth 1.5 × distance between anterolateral spines. Dorsal surface smooth, with shallow depression between gastric and cardiac regions; pair of epigastric spines varying from small to good size. Lateral margins somewhat convex, anterolateral spine usually small but larger than lateral orbital spine, located posterior to level of that spine, usually not reaching, occasionally reaching or slightly overreaching it; anterior end of branchial region with somewhat elevated ridge or very small spine, followed by denticle-like or obsolescent very small spines; ridged along posterior half or posterior third. Rostrum narrowly triangular, with interior angle of 21-25°, straight horizontal or directed slightly ventrally; dorsal surface flattish; length 0.4-0.5 × that of remaining carapace, breadth half carapace breadth at posterior carapace margin. Pterygostomian flap anteriorly not sharply produced but somewhat roundish, ending in small spine; surface glabrous and spineless.

Sternum: Excavated sternum with anterior margin broadly triangular with small median spine, surface with small spine in center. Sternal plastron 0.9 × as long as broad, lateral extremities gently divergent posteriorly. Sternite 3 well depressed; anterior margin strongly excavated, with subovate or narrow median notch flanked by spine often accompanying a few small spines lateral to each, anterolaterally sharp angular. Sternite 4 with transverse row of denticles or tubercles on surface; anterolateral margin with posteriorly diminishing spines, length 1.5 × that of posterolateral margin.

Abdomen: Smooth and glabrous. Somite 1 with antero-posteriorly convex transverse ridge. Somite 2 tergite 2.2-2.7 × broader than long, pleural lateral margin strongly divergent posteriorly, posterolaterally blunt. Pleura of somites 3 and 4 also bluntly angular laterally. Telson 0.55-0.68 × as long as broad, posterior plate 1.5-2.0 × length of anterior plate, distinctly emarginate on posterior margin.

Eye: 1.6-2.0 × longer than broad, overreaching midlength of and not reaching apex of rostrum; mesial margin concave. Cornea slightly broader than and about as long as remaining eyestalk.

Antennule and antenna: Ultimate article of antennular peduncle 1.9-2.0 × longer than high. Antennal peduncle slender, not overreaching cornea. Article 2 with distinct distolateral spine. Antennal scale terminating in or overreaching midlength of and barely reaching distal end of article 5; breadth 1.5 × that of article 5. Articles 4 and 5 unarmed; article 5 2.2-2.6 × longer than article 4, breadth less than half height of ultimate article of antennule. Flagellum of 12-15 segments barely reaching distal end of P1 merus.

Mxp: Mxp1 with bases very close to each other. Mxp3 relatively slender, barely setose on lateral surfaces of ischium and merus. Basis with 3-5 proximally diminishing denticles on mesial ridge. Ischium with flexor margin not rounded distally, crista dentata with 14-15 denticles. Merus and carpus unarmed; merus twice as long as ischium, with weak ridge along flexor margin bearing sparse long setae, mesial and lateral faces convex.

P1: 4.5-5.0 × longer than carapace, slender, subcylindrical but somewhat depressed on fingers and palm, with setae relatively short on fingers, almost glabrous elsewhere; small tubercles occasionally present on ventral surfaces of palm, carpus and merus in large specimens, obsolete or absent in small specimens. Ischium with basally broad, depressed, short triangular dorsal spine, ventromesial margin with tubercular processes on proximal part, lacking subterminal spine. Merus 1.1-1.3 × longer than carapace. Carpus 1.1-1.3 × longer than merus. Palm 2.9-3.4 × (males), 3.9-4.5 ×, rarely 5.8 × (females) longer than broad, subequal to or slightly shorter than carpus. Fingers not gaping in females (opposable margin of movable finger with low proximal process); gaping in males (movable finger with obtuse process occasionally bidentate at midlength of gaping portion); fingers fitting in distal third, ending in small incurved spine, slightly crossing when closed; movable finger 0.5-0.6 × length of palm.

P2-4: Slender and well compressed mesio-laterally, bearing long setae on distal articles. Meri successively shorter posteriorly (P3 merus 0.8-0.9 × length of P2 merus, P4 merus 0.7-0.8 × length of P3 merus), subequally broad on P2-3, slightly narrower on P4; length-breadth ratio, 5.2-6.5 on P2, 4.7-6.0 on P3, 3.9-4.8 on P4; dorsally unarmed, ventrolaterally bearing terminal spine; P2 merus 0.8-0.9 × length of carapace, 1.2-1.3 × (1.1 × in small specimens) longer than P2 propodus; P4 merus 0.8-0.9 × length of P4 propodus. Carpi successively shorter posteriorly; carpuspropodus length ratio, 0.54-0.56 on P2, 0.51-0.54 on P3, 0.43-0.50 on P4; carpus-dactylus length ratio, 1.2-1.4 on P2, 1.0-1.2 on P3, 0.9-1.0 on P4. Propodi successively shorter posteriorly; flexor margin with long, slender spines usually along entire length at least on P2: 7-8 spines on P2, 5-6 spines on P3, 4-5 spines on P4; terminal spine single, relatively remote from juncture with dactylus, equidistant between distal second spine and juncture or closer to second. Dactyli more slender than propodi, strongly curving at proximal third; dactylus-propodus length ratio, 0.41-0.46 on P2, 0.41- 0.47 on P3, 0.46-0.48 on P4; flexor margin with relatively large, loosely spaced, obliquely directed, triangular spines 8-10 (mostly 9) in number, ultimate larger than penultimate, antepenultimate more remote from penultimate than from distal quarter.

Eggs. Number of eggs carried 5-20; size, 1.93 mm × 2.07 mm - 2.10 mm × 2.50 mm.

REMARKS — According to S.T. Ahyong (pers. comm.), all the material reported by Ahyong & Poore (2004) under U. gracilimanus is referable to this species: the anterior margin of sternite 3 is usually moderately excavated on the Australian specimens of Ahyong & Poore (2004), sometimes shallowly excavated as illustrated by Ahyong & Poore (2004: fig 10E), but usually deeper being more like Figure 162C .

Most of the present material generally fits the description and illustration of the type material from the Andaman Sea ( Alcock 1901: 283, pl. 3, fig. 3; Alcock & McArdle 1902: pl. 56, fig. 3) but it is not in complete agreement in having the carapace lateral marginal spines usually tiny or obsolescent, occasionally small and not so distinct as illustrated for the type and in having the epigastric spines small, not so clearly large as in the type. If the figure of the Investigator material is correctly illustrated, the P4 merus is as long as the P4 propodus whereas it is 0.8-0.9 times as long in the MNHN specimens ( Figures 162 , 163 ).

The specimens taken at MUSORSTOM 8 Stn CP1129, Vanuatu (MNHN-IU-2014-16827) have more closely arranged spines along the propodal flexor margins of P2-4, compared with the rest of the material examined. In one of the males ( Figures 164 , 165 ), sternite 3 is more strongly excavated.

The Albatross material reported earlier from the Philippines and Indonesia ( Baba 1988) seems to contain two or three different species: 1) one ovigerous female from Albatross Station 5660 (USNM 151644) ( Figures 166 , 167 ) looks identical with the present material; 2) one male and two females from Albatross Station 5527 (USNM 151639) are very similar to the above but differ in having the pterygostomian flap more roundish anteriorly with a tiny spine and in having the P2 merus slightly longer than the carapace ( Figures 168 , 169 ); 3) one male from Albatross Station 5274 (USNM 151638) has a upturned rostrum, the carapace lateral spines more distinct and much like that of the type, the pterygostomian flap anteriorly more or less angular with a distinct spine and the P2 merus 0.9 times as long as the carapace ( Figures 170 , 171 ).

The material from Madagascar ( Baba 1990) contains two species. One is represented by a female (6.1 mm) from Vauban Station CH 138 (MNHN-IU-2013-7805). It is similar to the western Australian specimen reported by Ahyong & Baba (2004; see below), having relatively long P2-4 carpi (carpus-dactylus length ratio, 2.0 on P2, 1.9 on P3, 1.7 on P4), but it differs from that specimen in having obsolescent carapace lateral spines, in having the anterolateral spines overreaching the lateral orbital spine, and in having the pterygostomian flap anteriorly more angular and produced to a distinct spine; this species is apparently new. The other species is represented by the rest of the material from Madagascar (see Baba 1990), which is identical with a specimen collected by Mainbaza Station CP 3139 in the Mozambique Channel [23°33.51’S, 36°7.27’E, 1092-1195 m, 11 Apr 2009, 1 female 10.6 mm, MNHN-2010-5450 (see Figures 172 , 173 )]. These specimens are morphologically hardly discriminated from the material around New Caledonia and vicinity.

The specimens from three different localities in the western Indian Ocean collected by the John Murray Expedition ( Tirmizi 1964) are identical with those taken at Galathea Station 241 off Kenya ( Baba 2005; ZMUC CRU-11279). These specimens are different from the above-mentioned western Indian Ocean material, having a small spine in midline slightly posterior to the position of a pair of epigastric spines. They appear to be an undescribed species.

Ahyong & Baba (2004) described a western Australian specimen that has well-developed carapace lateral spines and deep cervical groove, noting that the P2 merus is longer than the carapace. In addition, the specimen has longer carpi on P2-4 (the P2 carpus is nearly twice the length of the P2 dactylus), whereas this article in the holotype is shorter, 1.2 times longer than the dactylus if the figure ( Alcock & McArdle 1902: pl. 56, fig. 3) is correctly depicted; and the P3 merus is subequally long as the P2 merus rather than shorter (0.9 times as long). These features are consistent in additional material examined (Soela Stn NWS-29, 17°55.5’ S, 118°19.5’ E, 450-454 m, 27.I.1984, 1 ovigerous female 11.5 mm (NTM Cr. 000649); Soela Stn NWS-47, 18°34.3’ S, 117°30.0’ E, 404 m, 01.II.1984, 1 ovigerous female 10.0 mm (NTM Cr. 000650); Soela Stn NWS-52, 18°05.8’ S, 118°10.0’ E, 408- 396 m, 02.II.1984, 1 male 10.8 mm (NTM Cr. 000566)). Baba et al. (2009) noted that the three specimens collected off Taiwan and identified as U. nigricapillis are identical with the western Australian specimen of Ahyong & Baba (2004). In the MNHN material, the P2 merus is 0.8-0.9 times as long as the carapace and the P3 merus is 0.8-0.9 times the length of P2 merus. The western Australian and Taiwanese specimens have been described as U. michaeli by Ahyong & Baba (unpublished).

All of the above-mentioned specimens may be referable to more than four species constituting a species complex, which should be solved by examination of the type material of U. nigricapillis . However, access to the type is hardly possible, because repeated inquiries to the Zoological Survey of India, the repository of the type, have been ignored. All

of these are provisionally placed in U. nigricapillis sensu lato until the systematic status of U. nigricapillis is established by examination of the type material or by a discovery of topotypic material.

The material from Saya de Malha Bank in the western Indian Ocean ( Laurie 1926) will in all probability be referable to U. longioculus Baba, 1990 , according to the inconsistencies listed by Laurie.

Figures

FIGURE 162 Uroptychus nigricapillis Alcock,1901,ovigerous male 9.0 mm (MNHN-IU-2013-12297).A, carapace and anterior part of abdomen, proximal part of left P1 included, dorsal. B, same, lateral.C, sternal plastron, with excavated sternum and basal parts of Mxp1. D, telson. E, right antenna, ventral.F, right Mxp3, ventral.G, same, lateral.Scale bars:1 mm.

FIGURE 163 Uroptychus nigricapillis Alcock,1901,ovigerous male 9.0 mm (MNHN-IU-2013-12297).A, left P1, proximal part,ventral.B, same, proximal part omitted, dorsal. C, right P2, lateral. D, same, distal part, setae omitted, lateral. E, right P3, setae omitted, lateral. F, same, distal part, lateral.G, right P4,lateral.H, same, distal part, lateral. Scale bars: A, B, 5 mm; C-H,1 mm.

FIGURE 164 Uroptychus nigricapillis Alcock, 1901, male 6.2 mm (MNHN-IU-2013-12296). A, carapace and anterior part of abdomen, proximal part of left P1 included, dorsal.B, same,lateral.C, sternal plastron,with excavated sternum and basal parts of Mxp1. D, telson.E, left antenna, ventral.F, right Mxp3, ventral.G, same,lateral.Scar bars:1 mm.

FIGURE 165 Uroptychus nigricapillis Alcock,1901,male 6.2 mm (MNHN-IU-2013-12296).A,left P1,proximal part,setae omitted,lateral.B,same, ventral.C, same, proximal part omitted, dorsal. D, right P1, fingers, dorsal. E, left P2, lateral. F, same, distal part, setae omitted, lateral.G, right P3, lateral.H, same,distal part,lateral.I, right P4, lateral.J, same, distal part, lateral.Scale bars: 1 mm.

FIGURE 166 Uroptychus nigricapillis Alcock, 1901, female 10.0 mm (USNM 151644) from Indonesia. A, carapace and anterior part of abdomen, dorsal.B, same, lateral.C, sternal plastron, with excavated sternum and basal parts of Mxp1. D, telson.E, left antenna,ventral.F, right Mxp3,ventral.G, same,lateral. Scale bars:A, B, 5 mm; C-G,1 mm.

FIGURE 167 Uroptychus nigricapillis Alcock, 1901, female 10.0 mm (USNM 151644) from Indonesia. A, left P1, dorsal. B, same, proximal part, ventral.C, right P2, lateral. D, same, distal part, setae omitted, lateral. E, right P3, setae omitted, lateral.F, right P4, lateral.G, same, distal part,lateral.Scale bars:A,B, 5 mm; C-G,1 mm.

FIGURE 168 Uroptychus nigricapillis Alcock, 1901, ovigerous female 7.3 mm (USNM 151639) from the Philippines. A, carapace and anterior part of abdomen,dorsal.B, same,lateral.C, carapace,anterior part,lateral.D, sternal plastron,with excavated sternum and basal parts of Mxp1. E, telson.F, left antenna,ventral.G, left Mxp3, ventral.H, same, lateral. Scale bars: 1 mm.

FIGURE 169 Uroptychus nigricapillis Alcock, 1901, ovigerous female 7.3 mm (USNM 151639) from the Philippines. A, right P1, dorsal. B, same, proximal part, ventral.C, right P2, lateral. D, same, distal part, setae omitted, lateral. E, right P3, setae omitted, lateral.F, same,distal part, lateral.G, right P4, lateral.H, same,distal part, lateral.Scale bars: 1 mm.

FIGURE 170 Uroptychus nigricapillis Alcock, 1901, male 7.9 mm (USNM 151638) from the Philippines. A, carapace, dorsal. B, same, anterior part of abdomen included, lateral. C, carapace lateral margin, slightly dorsomesial. D, carapace, anterior part, lateral. E, sternal plastron, with excavated sternum and basal parts of Mxp1.F, telson.G, right antenna,ventral.H, right Mxp3, ventral.I, same, lateral.Scale bars:1 mm.

FIGURE 171 Uroptychus nigricapillisAlcock,1901,male 7.9 mm (USNM 151638) from the Philippines.A, right P1,dorsal.B, same,proximal part,ventral. C, same,fingers, ventral. D, left P2, lateral. E, same,distal part,setae omitted, lateral.F, left P3, setae omitted,lateral.G, same, distal part, lateral.H, left P4, lateral.I, same,distal part,lateral.Scale bars:A-C,5 mm;B-I, 1 mm.

FIGURE 172 Uroptychus nigricapillis Alcock,1901,female 10.6 mm from Mozambique Channel (MNHN-IU-2010-5450).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, right antenna,ventral.F, right Mxp3, ventral.G, same, lateral.Scale bars: A,B,5 mm; C-G,1 mm.

FIGURE 173 Uroptychus nigricapillis Alcock,1901, female 10.6 mm from Mozambique Channel (MNHN-IU-2010-5450).A, right P1, proximal,ventral. B, same,proximal articles omitted, dorsal.C, same, fingers, ventral. D, right P2,lateral.E, same,distal part, setae omitted, lateral.F, right P3, setae omitted, lateral.G, right P4,lateral. Scale bars:A-C, 5 mm; B-G, 1 mm.