Stylodactylus A. Milne-Edwards, 1881

Cleva, Régis & Wormhoudt, Alain Van, 2006, On two rare and poorly known species, Stylodactylus discissipes Bate, 1888, and S. serratus A. Milne-Edwards, 1881 (Crustacea, Decapoda, Stylodactylidae), Zoosystema 28 (2), pp. 347-358 : 349-354

Genus Stylodactylus A. Milne-Edwards, 1881

Stylodactylus discissipes Bate, 1888 ( Figs 1 ; 2 ; 4A ; Table 1)

Stylodactylus discissipes Bate, 1888: 851 , pl. 138, fig. 1. Stylodactylus orientalis Bate, 1888: 854 , pl. 138, fig. 2.

Non Stylodactylus discissipes – Rathbun 1906: 927, fig. 75, pl. 23, fig. 1 (= Stylodactylus kauaiensis Figueira, 1971 ).

MATERIAL EXAMINED. — Kermadec Islands (North of New Zealand). Challenger, stn 171, 28°33’S, 177°50’W, trawl, 1097 m, 15.VII.1874, 1 ♀ c. 8 mm (holotype), 1 ♀ 11 mm (holotype of S. orientalis ) (NHM 88-22).

New Caledonia, Norfolk Ridge. NORFOLK 2, stn DW 2054, 23°40’S, 168°15’E, 736-800 m, 24.X.2003, 1 ♀ 6 mm (MNHN-Na 15728). — Stn DW 2065, 25°16’S, 168°56’E, 750-800 m, 26.X.2003, 1♀ 13.5 mm (MNHN-Na 15729). — Stn DW 2072, 25°21’S, 168°57’E, 1000-1005 m, 26.X.2003, 2 ovig. ♀♀ 13 and 14 mm (MNHN-Na 15730). — Stn DW 2080, 25°20’S, 168°19’E, 764-816 m, 27.X.2003, 1♀ c. 12 mm (carapace damaged) (MNHN-Na 15731).

French Polynesia, Austral Archipelago, E of Rapa.

Specimen, Locality CL RL/CL Rostral Scapho/ Telson/ Telson/ Telson P3: P3: P4: P4: P5: P5: sex, depth (m) formula CL CL abd. 6 L/w Merus P/C Merus P/C Merus P/C coll. no. spines P/D spines P/D spines P/D ♀, NHM 88- Kermadec Is. 11 1.3 30(6)/15 0.46 0.62 – 2.5 11-11 2.1 13- 1.9 – – 22, holotype 1097 4.8 5.1

♀, NHM 88- Kermadec Is. 8 1.4 28(6)/14 – – – – 10- – 11- – 11- – 22, holotype 1097

of S.orientalis

♀ ov.,MNHN- N. Caledonia 14 1.35 28 + (6)/16 0.45 0.70 1.6 2.6 8- 2.0 12- – 10-11 2.1 Na 15730 1000-1005 tip missing 6.0 9.0 ♀ ov.,MNHN- N. Caledonia 13 – – (6) – – 0.68 1.7 2.7 – – – – – – Na 15730 1000-1005

♀, MNHN- N. Caledonia c. 12 – – (6) – – – 1.8 2.7 10-10 2.2 12- 2.2 10-12 2.2 Na 15731 764-816 5.5 6.7 7.5 ♀, MNHN- N. Caledonia 13.5 – – (6) – 0.46 0.68 1.8 2.6 – – – – – – Na 15729 750-800

♀, MNHN- N. Caledonia c. 6 – – (4) – 0.48 – – – 4- 1.8 12- – 11- – Na 15728 736-800 4.8

♀, MNHN- Austral Is. c. 13.5 1.2 27(5)/20 0.45 0.67 1.8 2.6 12-12 2.2 12-13 1.9 12-12 1.8 Na 15725 840-1200 4.7 4.9 6.3 ♀, MNHN- Austral Is. 10 1.6 33(5)/19 0.52 0.68 1.6 2.7 12-13 2.1 14-14 2.0 – – Na 15726 840-1200 4.8 5.5

♀ MNHN- Austral Is. 15 – – (5) – – 0.70 1.6 2.5 – – – – – – Na 15726 840-1200

♀ ov.,MNHN- Austral Is. 16 1.2 30(7)/17 0.46 0.68 1.7 2.6 9- 2.1 – – – – Na 15726 840-1200 tip missing 5.2

♂, MNHN- Austral Is. 15 – – (6) – 0.45 0.64 1.6 2.7 – – – – – – Na 15726 840-1200

♀ ov.,MNHN- Austral Is. 16.5 c. 1.25 26 + (5)/17 + 0.44 0.72 1.7 2.8 10-11 2.1 12- 2.1 11- 2.0 Na 15727 900-1300 tip missing 5.9 6.9 8.3 ♂, MNHN- Austral Is. 12-13 – – (5) – – – – 2.8 – – 13- – – – Na 15727 900-1300 damaged

BENTHAUS, stn CP 1910, 27°38.2’S, 144°15.4’W, 840-1200 m, 10.XI.2002, 1 ♀ 13.5 mm, photographed (MNHN-Na 15725); 1 ♂ 15 mm, 3 ♀♀ (1 ovig.) 10-16 mm (MNHN-Na 15726). — Stn CP 1911, 27°37.9’S, 144°15.2’W, 900-1300 m, 10.XI.2002, 1 ♂ c. 12 or 13 mm (carapace damaged), 1 ovig. ♀ 16.5 mm (MNHN-Na 15727).

DISTRIBUTION. — Kermadec Is., 1097 m; New Caledonia, 736-1005 m ; French Polynesia, Austral Is. (Rapa Is.), 840-1300 m .

DIAGNOSIS. — Carapace with small supra-orbital spine. Antennal and branchiostegal spines well developed. Rostrum 1.2 to 1.6 times longer than carapace, bearing from 27 to 33 dorsal spines (four to seven on carapace proper, usually five or six), and from 14 to 20 ventral spines. Telson 0.62 to 0.72 carapace length and 1.6 to 1.8 longer than sixth abdominal somite. All abdominal pleura rounded. Antennal scale with outer edge entire except for terminal spine, about half length of carapace. Merus of last three pairs of pereiopods bearing series of strong external spines as follows: P3: eight to 13 (four for smallest specimen MNHN-Na 15728); P4: 12 to 14; P5: 10 to 12. Ratios P/C and P/D of last three pereiopods ranging as follows: P3: 1.8 to 2.2 and 4.7 to 6.0; P4: 1.9 to 2.2 and 4.9 to 6.9; P5: 1.8 to 2.2 and 6.3 to 9.0.

COLORATION ( FIG. 4A ) The colour photograph of a specimen collected from Rapa during BENTHAUS cruise (female 13.5 mm, MNHN-Na 15725) reveals no special pattern: general colour of body yellowish with anterior part of cephalothorax reddish; rostrum translucent; Mxp3, P1, P2 pinkish, other pereiopods pale yellowish; parts of telson and pleopods pale pinkish.

REMARKS A summary of morphological data for the specimens studied is provided in Table 1.

As previously mentioned, only two specimens of Stylodactylus discissipes were known, both from

Challenger station 171. The synonymy of S. orientalis with S. discissipes was evident to Kemp (1925: 258) and Crosnier & Forest (1973: 131). We have reexamined Bate’s two females (8 and 11 mm CL), both in poor condition, and have illustrated them ( Fig. 1 ). The telson of the smallest female is incomplete. The telson of the largest female is abnormal, having four dorsal spines on one side and three on the other; there are four pairs of spines at its extremity, which appears enlarged, whereas three pairs are usually present in all species of the genus.

A

Stylodactylus serratus A. Milne-Edwards, 1881 ( Figs 3 ; 4B ; Table 2)

Stylodactylus serratus A. Milne-Edwards, 1881: 11 ; 1883: pl. 36. — Faxon 1896: 160. — Figueira 1971: 2, fig. 1. — Crosnier & Forest 1973: 129, fig. 36a-f. — Cleva 1990: 166. — Fransen 1991: 191. — Forest & Holthuis 1997: 102 (pl. 36): 113, 116 (pl. A, appendix 1). — d’Udekem d’Acoz 1999: 92.

Non Stylodactylus serratus – Stebbing 1914: 51, pl. 12 (= Stylodactylus stebbingi Hayashi & Miyake, 1968 ).

MATERIAL EXAMINED. — Western Atlantic, West Indies. U.S. Coast Survey, Caribbean Islands Exploration, Blake, stn 190, off Dominique Island , 958 m, 1878- 1879, A. Agassiz coll., 1 ovig. ♀ 17.5 mm, holotype (MNHN-Na 7992). — U.S. Coast Survey , Caribbean Islands Exploration , off Martinique Island, Blake, stn 205, 14°25.15’N, 60°56.35’W, 611 m, 10.II.1879, A. Agassiz coll., 1 ♂ 13 mm (MNHN-Na 1850) ; 1 ♂ 17 mm (MNHN-Na 11276). — SE of St. Vincent, Pillsbury, stn P-881, 13°20.8’N, 61°02.5’W, 576-842 m, Blake trawl, 6.VII.1969, 1 ♂ 17.5 mm; 1 ♀ 20.5 mm ( RMNH D 38033 ). — N of Monserrat, Pillsbury, stn P-954, 16°55.0’N, 62°43.0’W, 686-1043 m, Blake trawl, 18.VII.1969, 1 ♂ 12.5 mm ; 1 ovig. ♀ 18 mm ( RMNH D 38034 ). Eastern Atlantic , off south Portugal ( Banc Joséphine ). SEAMOUNT I ATLANTIQUE, stn CP 50, 36°47.4’N, 14°31.7’W, 1360-1380 m, 6.X.1988, 1 ovig. ♀ 21 mm (MNHN-Na 15732). Canary Islands. CANCAP 2, stn 131, SW of Hierro, off Punta de Orchilla, 27°40’N, 18°10’W, 1200-1800 m, Agassiz trawl, 8.IX.1977, 2 ♀♀ 18 and 19.5 mm (ovig.) ( RMNH D 38035) .

ably belonging to P3; 4, appendages detached, may belong to P4 or P5. Abbreviations: see Table 1.

Rio de Oro, Spanish Sahara (currently Morocco). Talisman , stn 73, 25°39’N, 16°06’W, 1435 m, 9.VII.1883, 1 ♂ 12.5 mm (MNHN-Na 1851).

DISTRIBUTION. — Western Atlantic : West Indies, 576- 1043 m. Eastern Atlantic: off south Portugal (Banc Joséphine), 1360-1380 m ; Canary Is., 1200-1800 m; Rio de Oro (Spanish Sahara), 1435 m .

DIAGNOSIS. — Carapace with very small supra-orbital spine, antennal and branchiostegal spines well developed. Rostrum 1.25 to 1.7 times longer than carapace, with 38 dorsal and 28 ventral spines on the unique specimen with intact rostrum; seven or eight spines on carapace proper, behind orbit.Telson 0.66 to 0.75 carapace length, and 1.6 to 1.8 longer than sixth abdominal somite. Abdominal pleurae rounded. Antennal scale with outer edge entire except for terminal spine, about half length of carapace. Merus of last three pairs of pereiopods bearing series of strong external spines: P3: 13 to 15; P4: 13 to 17; P5: 12 to 15. Ratios P/C and P/D of last three pereiopods ranging as follows: P3: 2.1 to 2.2 and 4.5 to 5.5 (6.4?); P4: 2.0 to 2.2 and 6.8 to 8.2; P5: 1.9 to 2.2 and 7.6 to 10.5.

COLORATION ( FIG. 4B )

A.Milne-Edwards’s illustration published by Forest & Holthuis (1997: 116), reproduced herein ( Fig. 4B ), indicates that coloration of this species is very similar to that of S. discissipes .

REMARK

A summary of morphological data for the specimens studied is provided in Table 2.

Figures

FIG. 1. — Stylodactylus discissipes Bate, 1888, anterior part of body and eye, lateral (A, C) and telson, dorsal (B): A, B, ♀ 11 mm, Ker- madec Is., Challenger, stn 171, holotype of S. orientalis (NHM 88-22); C, ♀ 8 mm, holotype, same origin, same registration number. Scale bars: A, C, 5 mm; B, 3 mm.

FIG. 2. — Stylodactylus discissipes Bate, 1888, anterior part of body with eye, stylocerite and antennal scale: A, ovigerous ♀ 14 mm, New Caledonia, Norfolk Ridge, NORFOLK 2, Alis, stn DW 2072 (MNHN-Na 15730); B, ♀ 13.5 mm, French Polynesia, Austral Is., east of Rapa I., BENTHAUS, Alis, stn CP 1910 (MNHN-Na 15725). Scale bars: 5 mm.

FIG. 4.— Colour pattern:A, Stylodactylus discissipes Bate,1888,♀ 13.5 mm,French Polynesia,Austral Is., east of Rapa I., BENTHAUS, Alis, stn CP 1910 (MNHN-Na 15725); B, Stylodactylus serratus A. Milne-Edwards, 1881 (from Forest & Holthuis 1997).

FIG. 3. — Stylodactylus serratus A.Milne-Edwards,1881,anterior part of body with eye (B), antennal scale (A): A, ovigerous ♀ 17.5 mm, holotype, West Indies, off Dominique I., Blake, stn 190 (MNHN-Na 7992); B, ovigerous ♀ 21 mm, off Gibraltar Strait, SEAMOUNT 1 ATLANTIQUE, stn CP 50 (MNHN-Na 15732). Scale bar: 5 mm.