Uroptychus lumarius, Baba, 2018

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 : 286-290

Uroptychus lumarius n. sp.

Figures 133 , 134

TYPE MATERIAL — Holotype: New Caledonia, Norfolk Ridge. BATHUS 3 Stn CP811, 23°41’S, 168°15’E, 383-408 m, 28.XI.1993, ♂ 3.6 mm ( MNHN-IU-2013-8516 ) . Paratypes: Solomon Islands. SALOMON 1 Stn DW1852, 09°47’S, 160°53’E, 236-250 m, 07.X.2001, 1 ov. ♀ 3.6 mm (MNHN-IU-2014-16698) . New Caledonia, Norfolk Ridge. BATHUS 2 CP736 23°03’S, 166°58’E, 452-464 m, 13.V.1993, 1 ♂ 3.4 mm, 2 ov. ♀ 3.2, 3.3 mm, 1 ♀ 3.2 mm (MNHN-IU-2014-16699) . BATHUS 3, station data as for the holotype, 1 ♂ 3.5 mm, 4 ov. ♀ 3.3-3.5 mm (MNHN-IU-2014-16700) . – Stn DW818, 23°44’S, 168°16’E, 394-401 m, 28.XI.1993, 1 ♂ 3.0 mm, 1 ov. ♀ 2.8 mm (MNHN-IU-2014-16701) . LITHIST Stn DW13, 23°45.0’S, 168°16.7’E, 400 m, 12.VIII.1999, 1 ♂ 3.1 mm (MNHN-IU-2014-16702) . – Stn CP15, 23°40’S, 168°15’E, 389- 404 m, 12.VIII.1999, 1 ♀ 3.5 mm (MNHN-IU-2014-16703) . NORFOLK 1 Stn CP1706, 23°44’S, 168°17’E, 383-394 m, 25.VI.2001, 1 ♀ 3.3 mm (MNHN-IU-2014-16704) . – Stn DW1707, 23°43’S, 168°16’E, 381-493 m, 25.VI.2001, 1 ov. ♀ 3.5 mm (MNHN-IU-2014-16705) . NORFOLK 2 Stn CP2048, 23°43.82’S,168°16.24’E, 380-389 m, with Primnoidae gen. sp. ( Calcaxonia ), 24.X.2003, 10 ♂ 2.9-3.5 mm, 7 ov. ♀ 3.2-3.5 mm (MNHN-IU-2014-16706) . – Stn CP2050, 23°42.17’S, 168°15.72’E, 377-377 m, 24.X.2003, 1 ♂ 3.0 mm, 1 ov. ♀ 2.9 mm (MNHN-IU-2014-16707) . – Stn DW2052, 23°42.29’S, 168°15.27’E, 473-525 m, 24.X.2003, 1 ov. ♀ 3.2 mm (MNHN-IU-2014-16708) . – Stn DW2108, 23°46.52’S, 168°17.12’E, 403-440 m, 31.X.2003, 1 ♂ 2.8 mm, 1 ♀ 3.3 mm (MNHN-IU-2014-16709) . – Stn DW2109, 23°47.46’S, 168°17.04’E, 422-495 m, 31.X.2003, 1 ♂ 3.0 mm, 1 ov. ♀ 3.2 mm (MNHN-IU-2014-16710) . BERYX 11 Stn CP51, 23°44’S, 168°17’E,

390-400 m, 21.X.1992, 5 ♂ 3.2-3.7 mm, 4 ov. ♀ 3.2-3.6 mm, 2 ♀ 3.5, 3.9 mm (MNHN-IU-2014-16711). – Stn CP52, 23°47.45’S, 168°17.05’E, 430-530 m, 21.X.1992, 1 ♂ 2.8 mm (MNHN-IU-2014-16712) . Philippines. MUSORSTOM 2 Stn CP51, 14°00’N, 120°17’E, 170-187 m, with corals of Antipatharia (Hexacorallia), 27.XI.1980, 1 ♂ 3.9 mm (MNHN- IU-2014-16713) . MUSORSTOM 3 Stn CP134, 12°01’N, 121°57’E, 92-95 m, with possibly Dendronephthya sp. ( Alcyoniina : Nephtheidae ), 5.VI.1985, 1 ov. ♀ 3.5 mm (MNHN-IU-2014-16714) .

ETYMOLOGY„ From the Latin lumarius (of thorns), alluding to strong spines on the flexor margin of P2-4 dactyli, by which the species is easily distinguished from the other three congeners, U. floccus , U. quinarius and U. dualis .

DISTRIBUTION„ Philippines, Solomon Islands, and Norfolk Ridge; 92- 530 m.

SIZE„ Males, 2.8-3.9 mm; females, 2.8-3.9 mm; ovigerous females from 2.8 mm. DESCRIPTION„ Small species. Carapace: As long as broad; greatest breadth 1.5 × distance between anterolateral spines. Dorsal surface slightly convex from anterior to posterior, bearing shallow depression between gastric and cardiac regions; with sparse short fine setae and a few small spines on hepatic region: usually 2 placed side by side mesial to between third and fourth lateral spines, rarely 3, 1 or 0. Lateral margins slightly divergent posteriorly, bearing 8 spines along entire length, rarely with additional obsolescent spine behind anterior third spine; first anterolateral, moderately developed, overreaching much smaller lateral orbital spine; second and third small; fourth to seventh strong and subequal, last spine small or obsolete. Rostrum narrow triangular, with interior angle of about 20°, laterally with small subapical spine (rarely 2) on each side, dorsally excavated longitudinally; length 0.5-0.7 × that of remaining carapace, breadth half carapace breadth at posterior carapace margin. Lateral orbital spine small, situated at same level as anterolateral spine. Pterygostomian flap anteriorly angular, produced to strong spine, surface with small spines on anterior half, one consistent directly below linea anomurica between third and fourth lateral spines.

Sternum: Excavated sternum with longitudinal ridge in midline on anterior half, anterior margin broadly triangular or convex between bases of Mxp1. Sternal plastron about as long as broad or slightly longer, lateral extremities subparallel between sternites 4 and 7. Sternite 3 moderately depressed; anterior margin shallowly excavated with deep median notch usually of narrow, rarely moderately broad U-shape or narrow V-shape flanked by small or obsolescent spine; anterolateral angle sharply produced. Sternite 4 with nearly straight anterolateral margin anteriorly ending in 1 or 2 (placed side by side) small spines; posterolateral margin relatively long, slightly shorter than anterolateral margin. Anterolateral margin of sternite 5 as long as posterolateral margin of sternite 4.

Abdomen: Tergites smooth, sparsely setose. Somite 1 moderately convex from anterior to posterior. Somite 2 tergite 3.1-3.5 × broader than long; pleuron anterolaterally and posterolaterally bluntly angular, lateral margin strongly concave, not divergent posteriorly. Pleuron of somite 3 tapering, laterally angular. Telson less than half (0.33-0.45 x) as long as broad; posterior plate 1.0-1.3 × longer than anterior plate, posterior margin nearly transverse or feebly concave.

Eye: Elongate (1.9 × longer than broad), slightly overreaching midlength of rostrum, distally narrowed, bearing a few setae dorsally. Cornea not dilated, about half as long as remaining eyestalk.

Antennule and antenna: Ultimate article of antennular peduncle 2.5-2.9 × longer than high. Antennal peduncle overreaching cornea. Article 2 with sharp, strong lateral spine. Antennal scale overreaching article 5 by length of proximal 2 segments of flagellum, slightly falling short of rostral tip, breadth 2.0-2.5 × that of article 5. Distal 2 articles with strong distomesial spine. Article 5 1.3 × longer than article 4, breadth two-thirds height of ultimate antennular article. Flagellum of 9-14 segments far falling short of distal end of P1 merus (rarely 19 segments reaching distal end of P1 merus (male, MNHN-IU-2014-16713)).

Mxp: Mxp1 with bases distantly separated. Mxp3 with sparse long setae on ischium, merus and carpus. Basis with or without obsolescent denticles. Ischium with distally diminishing denticles on crista dentata, distolaterally bearing small spine somewhat lateral to rounded distal end of flexor margin. Merus 2 × longer than ischium, mesio-laterally compressed, mesial face smooth, slightly concave; flexor margin with 1 or 2 small spines distal to point one-third from distal end; distolateral spine well-developed. Carpus with 1 well-developed distolateral and 1 or 2 small extensor proximal spines.

P1: Sparingly setose, 4.1-5.5 × longer than carapace. Ischium dorsally with 2 spines (distal larger), ventromesially with strong subterminal spine proximally followed by small spines. Merus with field of 3 spines in oblique row on proximomesial surface (from dorsal to ventral) and 4 strong ventromesial spines; length 1.0-1.2 × that of carapace. Carpus 1.2-1.4 × (rarely subequal to) length of merus, ventrally bearing distomesial and distolateral spines. Palm 3.0-3.5 × (males), 2.7-3.7 × (females) longer than broad, 1.2-1.4 × (rarely 1.1 x) longer than carpus. Fingers somewhat incurved distally; opposable margins not gaping in both sexes, that of fixed finger with low eminence distal to position of opposite median low process on movable finger; movable finger 0.4-0.5 × length of palm.

P2-4: Moderately compressed mesio-laterally, relatively broad, setose like P1. Meri successively shorter posteriorly (P3 merus 0.9 × length of P2 merus, P4 merus 0.8-0.9 × length of P3 merus), equally broad on P2-4; length-breadth ratio, 3.6-4.5 on P2, 3.3-3.9 on P3, 3.1-3.4 on P4; P2 merus 0.7-0.9 × length of carapace, 1.1-1.2 × length of P2 propodus; P3 merus subequal to length of P3 propodus; P4 merus 0.8 × length of P4 propodus; dorsal margin with row of 3-5 small spines

distinct on P2, 2 spines occasionally obsolescent on P3, no spine but a few setiferous eminences on P4, unarmed on distal end; ventrolaterally with distal spine, ventromesially with 4-5 spines on P2, no spine on P3 and P4. Carpi successively very slightly shorter, length 0.4 that of propodus. Propodi shorter on P2 than on P3 and P4; flexor margin nearly straight, ending in pair of spines preceded by 4 or 5 spines on P2, 3 or 4 spines on P3, 1 or 2 spines on P4. Dactyli subequal in length on P3 and P4, slightly shorter on P2; slightly longer than carpi (dactylus-carpus length ratio, 1.1-1.3 on P2, 1.2-1.3 on P3, 1.3-1.5 on P4), about half as long as propodi (dactylus-propodus length ratio, 0.4-0.5 on P2 and P3, 0.5-0.6 on P4); similar in spination on P2-4; flexor margin straight, ending in slender spine preceded by 6 or 7 (usually 7) spines relatively large, subtriangular, obliquely directed, loosely arranged, and diminishing toward base of article, penultimate somewhat closer to ultimate than to antepenultimate, antepenultimate broader than ultimate.

Eggs. Number of eggs carried, 5-15; size, 0.9 mm × 1.0 mm - 1.0 mm × 1.3 mm.

REMARKS — The male collected from the Philippines at MUSORSTOM 3 Stn CP134 (MNHN-IU-2014-16714) is somewhat different from the others in having weaker spination of P2 merus, with the dorsal margin bearing a few obsolescent spines on the proximal part and the ventromesial margin unarmed but a very small proximal spine on the left side only. This specimen was collected together with the alcyonacean, possibly Dendronephthya sp. ( Nephtheidae ), whereas the lot MNHN-IU-2014-16713 from the Philippines was with antipatharian corals, and the specimens MNHN- IU-2014-16706 from the Norfolk Ridge was with alcyonacean coral Primnoidae . Given the different hosts, it is not unlikely that these may represent cryptic species but all are provisionally placed in U. lumarius .

The carapace bearing strong lateral spines and the P1 merus bearing a field of three spines in an oblique row on the proximal portion of the mesial surface link the species to U. dualis n. sp., U. floccus N. sp., and U. quinarius n. sp. These three congeners are characterized by sternite 4 with the posterolateral margin long relative to the anterolateral margin, and the P2-4 dactyli with numerous obliquely directed flexor marginal spines among which the distal second is pronouncedly broad and the remainder are slender and close to one another. In this new species, these spines are well developed, subtriangular, successively smaller toward the base of article, and loosely arranged. In addition, the carapace lateral margin bears 7-8 spines in U. lumarius , 6 spines in U. dualis and U. floccus , and 5 spines in U. quinarius .

Figures

FIGURE 133 Uroptychus lumarius n. sp., holotype, male 3.6 mm (MNHN-IU-2013-8516).A, carapace and anterior part of abdomen, proximal part of left P1 included, dorsal. B, same, lateral. C, anterior part of sternal plastron, with excavated sternum and basal parts of Mxp1. D, telson. E, left antenna, ventral. F, right Mxp3, setae omitted, ventral. G, same, lateral.H, right P1, proximal part, setae omitted,ventral.I, same,proximal articles omitted,dorsal. Scale bars:1 mm.

FIGURE 134 Uroptychus lumarius n.sp.,holotype,male 3.6 mm (MNHN-IU-2013-8516).A, left P2 and P3,distal part omitted,ventral.B, right P2,lateral.C, same, distal part, setae omitted. D, right P3,setae omitted, lateral. E, right P4, setae omitted, lateral.Scale bars:1 mm.