Uroptychus karubar, 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 : 249-252

Uroptychus karubar n. sp.

Figures 113 , 114

TYPE MATERIAL — Holotype: Indonesia, Kai Islands. KARUBAR Stn CP19, 5°15’S, 133°01’E, 605- 576 m, with corals Primnoidae gen. sp., Acanella sp. and Chrysogorgia sp. (all Calcaxonia ), 25.X.1991, ♂ 7.4 mm ( MNHN-IU-2014-16604 ) . Paratypes: Collected together with holotype, 4 ♂ 3.5-7.5 mm, 1 ov. ♀ 5.3 mm, 2 ♀ 4.2, 6.8 mm (MNHN-IU-2014-16605) . Solomon Islands. SALOMON 1 Stn DW1775, 8°12.6’S, 160°41.7’E, 498-600 m, 28.IX.2001, 1 ov. ♀ 4.9 mm ( MNHN- IU-2014-16606) . New Caledonia, Norfolk Ridge. NORFOLK 2 Stn DW2075, 25°23.12’S, 168°20.07’E, 650-1000 m, 27.X.2003, 1 ♂ 4.3 mm, 3 ov. ♀ 5.1-6.3 mm (MNHN-IU-2014-16607) . – Stn DW2087, 24°56.22’S, 168°21.66’E, 518- 586 m, 28.X.2003, 1 ov. ♀ 6.5 mm (MNHN-IU-2014-16608) .

ETYMOLOGY„ Named for the cruise KARUBAR, by which the holotype was collected; used as a noun apposition.

DISTRIBUTION„ Kai Islands, Solomon Islands and Norfolk Ridge; 518-1000 m.

SIZE„ Males, 3.5-7.5 mm; females, 4.2-6.8 mm; ovigerous females from 4.9 mm.

DESCRIPTION„ Medium-sized species. Carapace: broader than long (0.9 × as long as broad); greatest breadth 1.6 × distance between anterolateral spines. Dorsal surface moderately convex from side to side, slightly so from anterior to posterior, with feeble depression between gastric and cardiac regions and between anterior and posterior branchial regions; transverse row of 9-11 epigastric spines (median 3 rudimentary in ovigerous female MNHN-IU-2014-16606) preceded by depressed rostrum, followed by scattered small spines. Lateral margins somewhat convexly divergent posteriorly, with 6 spines: first anterolateral, distinctly overreaching much smaller lateral orbital spine; second smaller than first, equidistant between first and third and ventral to level of these spines; third largest, located at anterior end of anterior branchial region, with accompanying small spine dorsomesial to it; fourth to sixth on posterior branchial region, all acute, sixth followed by ridge. Rostrum straight horizontal, narrow triangular, with interior angle of 20-25°; length 0.5-0.6 × (rarely 0.7 x) postorbital carapace length, breadth less than half carapace breadth at posterior carapace margin; dorsal surface flattish; lateral margin with 4-6 spinules. Lateral orbital spine somewhat anterior to level of and moderately remote from anterolateral spine. Pterygostomian flap anteriorly angular, produced to sharp spine; surface covered with small spines.

Sternum: Excavated sternum anteriorly blunt angular, surface with weak ridge in midline. Sternal plastron slightly broader than long; lateral extremities gently divergent posteriorly. Sternite 3 well depressed, anterior margin deeply excavated, with 2 small submedian spines separated by semicircular or U-shaped sinus, laterally angular. Sternite 4 anterolaterally ending in sharp, anteriorly directed spine accompanied by small spine mesial to it; anterolateral margin somewhat concave, length subequal to that of posterolateral margin. Anterolateral margin of sternite 5 straight, slightly divergent posteriorly, anteriorly blunt angular, length 0.7-0.9 × that of posterolateral margin of sternite 4.

Abdomen: Somites smooth and glabrous. Somite 1 with distinct transverse ridge. Somite 2 tergite 2.5-2.7 × broader than long; pleuron with concavely divergent lateral margin leading to bluntly produced posterior terminus. Pleuron of somite 3 with bluntly angular lateral tip. Telson slightly less than half as long as broad; posterior plate 1.4-1.6 × longer than anterior plate, distinctly emarginate on posterior margin.

Eye: Terminating in midlength of rostrum, 1.5 × longer than broad, lateral and mesial margins subparallel. Cornea not dilated, length more than half that of remaining eyestalk.

Antennule and antenna: Ultimate article of antennule 3.5-4.1 × longer than high. Antennal peduncle extending far beyond cornea and falling short of rostral tip. Article 2 with strong lateral spine. Antennal scale twice as broad as article 5, reaching rostral tip and proximal quarter segment of flagellum. Articles 4 and 5 each with strong distomesial spine; article 5 1.4-1.9 × longer than article 4, breadth 0.5-0.6 × height of ultimate antennular article. Flagellum of 11-12 segments falling short of distal end of P1 merus.

Mxp: Mxp1 with bases close to each other but not contiguous. Mxp3 basis with 1 denticle on mesial ridge. Ischium with small spine slightly lateral to distal end of flexor margin; crista dentata with very small denticles; flexor margin not rounded distally. Merus 1.8 × longer than ischium; flexor margin well ridged, bearing a few small spines on distal third; distolateral spine distinct. Carpus also with well-developed distolateral spine and a few small spines along extensor margin.

P1: Relatively slender, sparingly setose but fingers more setose; length 5.4-6.6 × that of carapace. Ischium dorsally with sharp, curved spine, ventromesially with well-developed subterminal spine followed by a few proximally diminishing spines. Merus 1.3-1.5 × longer than carapace, with 4 rows of spines: 2 dorsal rows of small spines, 1 mesial row of strong spines (4 or 5 in number), and ventral row of 3-5 spines. Carpus 1.3-1.5 × longer than merus, about as long as palm, with 3 (rarely 4) rows of small spines (2 dorsal, 1 mesial, 1 ventral). Palm unarmed, 3.6-4.9 × (males), 4.3-6.1 × (females) longer than broad, 0.9-1.0 × length of carpus. Fingers gaping in males, not gaping in females, distally ending in papilla-like tip, not crossing; movable finger with bluntly triangular proximal process, length 0.4-0.5 × that of palm; opposable margin of fixed finger with longitudinal groove to accommodate opposite process of movable finger when closed.

P2-4: Relatively slender, moderately compressed mesio-laterally, sparsely setose. 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, 5.1-5.7 on P2, 4.5-5.7 on P3, 3.8-5.0 on P4; dorsal margin with 14-16 spines on P2, 11-17 on P3, 11-15 on P4; ventrolateral margin with 1 or 2 spines distally; ventromesial margin with 3 equidistant spines on P2 only, proximal 2 obsolete in small specimens; P2 merus 0.8-1.0 × length of carapace, 1.1-1.2 × length of P2 propodus; P3 merus very slightly longer than or subequal to P3 propodus; P4 merus 0.8-0.9 × length of P4 propodus. Carpi subequal on P2-4, on P2-3 (shorter on P4), or on P3-4 (longer on P2); carpus-propodus length ratio, 0.33-0.42 on P2, 0.31-0.39 on P3, 0.31-0.36 on P4; extensor margin with 5-7 spines on P2, 4-7 on P3, 3-4 on P4, terminal spine with accompanying spine lateral to it. Propodi subequal on P3 and P4, shorter on P2; flexor margin nearly straight, with pair of terminal spines preceded by 5-7 slender, movable spines on P2, 2-6 spines on P3, 2-5 spines on P4. Dactyli longer than carpi (dactyluscarpus length ratio, 1.2-1.3 on P2, 1.4-1.5 on P3, 1.3-1.6 on P4), about half as long as propodi on P2-4; flexor margin feebly curving, with 14 or 15 spines, ultimate spine slender, penultimate about twice as broad as ultimate, remaining spines similar to ultimate, but distally blunt, strongly inclined and nearly contiguous to one another.

Eggs. Number of eggs carried, 9-16; size, 0.91 mm × 0.96 mm - 1.16 × 1.09 mm.

REMARKS — The combination of the following characters link the species to U. alophus n. sp., U. echinatus n. sp., U. longior Baba, 2005 and U. nanophyes McArdle, 1901 : the P2-4 dactyli having the flexor margin with more than 10 closely arranged spines proximal to the pronounced penultimate spine, the P2-4 carpi with a few to several extensor marginal spines, and the carapace lateral margin with at least six spines. Among these species, Uroptychus nanophyes keys out first by having the antennal scale terminating in the distal end of the antennal article 5 and by having the P2 merus with a row of spines along the ventromesial margin. Uroptychus echinatus is distinctive in having the carapace thickly covered with setae and in having carapace lateral marginal spines much smaller. Uroptychus karubar is distinguished from U. alophus and U. longior by having a pair of epigastric spines and by the Mxp3 ischium bearing a small but distinct spine near the distal end of the flexor margin.

The new species also resembles U. vegrandis n. sp. from which it is readily distinguished by having a row of epigastric spines. More of distinguishing characters are outlined under the remarks of that species (see below).

Figures

FIGURE 113 Uroptychus karubar n. sp., holotype, male 7.4 mm (MNHN-IU-2014-16604). 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, setae omitted, lateral.H, left P1, proximal part, ventral.I, same,distal part, dorsal. Scale bars: A-G, 1 mm; H, I, 5 mm.

FIGURE 114 Uroptychus karubar n. sp., holotype, male 7.4 mm (MNHN-IU-2014-16604). A, right P2, lateral. B, same, distal part, setae omitted, lateral. C, right P3, lateral. D, right P4, lateral.Scale bars: 1 mm.