Uroptychus philippei, 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 : 394-398

Uroptychus philippei n. sp.

Figures 195 , 196

TYPE MATERIAL — Holotype: New Caledonia, Chesterfield Islands . CORAIL 2 Stn DE 16, 20°47.75’S, 160°55.87’E, 500 m, 21.VII.1988, ov. ♀ 4.0 mm (MNHN-IU-2013-8529) . Paratypes: New Caledonia, Chesterfield Islands. MUSORSTOM 5 Stn CP389, 20°44.95’S, 160°53.67’E, 500 m, 22.X.1986, 1 ov. ♀ 4.3 mm (MNHN-IU-2013-8527) . CORAIL 2 Stn DE16, station data as for holotype, 2 ov. ♀ 3.9, 4.0 mm, 1 ♀ 3.6 mm (MNHN-IU-2013-8528) ; 5 ♂ 3.3-4.3 mm, 4 ov. ♀ 3.6-4.1 mm, 3 ♀ 3.5-4.1 mm (MNHN-IU-2014-16856).

ETYMOLOGY„ Named for Philippe Bouchet of MNHN for his support and friendship.

DISTRIBUTION„ Chesterfield Islands; in 500 m.

SIZE„ Males, 3.3-4.3 mm; females, 3.5-4.3 mm; ovigerous females from 3.6 mm.

DESCRIPTION„ Small species. Carapace: 0.8-0.9 × as long as broad (1.1-1.2 × broader than long); greatest breadth 1.7- 1.9 × distance between anterolateral spines. Dorsal surface well convex from side to side and from anterior to posterior, with or without feeble groove between gastric and cervical regions, covered with short fine setae, smooth, occasionally bearing denticles sparse on hepatic and anterior branchial regions. Lateral margins moderately convexly divergent posteriorly with denticles arranged on short oblique ridges; anterolateral spine small, somewhat smaller than lateral orbital spine. Rostrum triangular, with interior angle of 25-30°, nearly horizontal; length 1.1-1.3 × breadth, slightly less than half that of remaining carapace, breadth less than half carapace breadth at posterior carapace margin; dorsal surface flattish, feebly concave at base; lateral margin with or without obsolescent spine near tip. Lateral orbital spine distinctly anterior to level of anterolateral spine. Pterygostomian flap covered with tiny denticles, anteriorly angular, produced to distinct spine.

Sternum: Excavated sternum with anterior margin convex between bases of Mxp1, surface with weak ridge in midline on anterior half. Sternal plastron 0.9-1.0 × as long as broad, lateral extremities slightly divergent or subparallel between sternites 4 and 7. Sternite 3 shallowly depressed, with anterior margin gently concave with U-shaped median sinus flanked by tiny spine, and laterally blunt or with a few denticles. Sternite 4 with relatively short anterolateral margin anteriorly ending in angular corner; posterolateral margin about as long as or slightly shorter than anterolateral margin. Anterolateral margin of sternite 5 anteriorly somewhat convex, slightly shorter than posterolateral margin of sternite 4.

Abdomen: Setose like carapace. Somite 1 convex from anterior to posterior. Somite 2 tergite 2.4 × broader than long; pleuron posterolaterally blunt, lateral margin weakly concave and slightly divergent posteriorly. Pleura of somites 3 and 4 laterally rounded. Telson slightly less than half as long as broad; posterior plate 1.1-1.3 × longer than anterior plate, posterior margin feebly concave or moderately emarginate.

Eye: Long relative to breadth (1.7-2.0 × longer than broad), ending in distal third of rostrum, slightly broader proximally or with subparallel lateral and mesial margins. Cornea not dilated, length 0.6-0.8 × that of remaining eyestalk.

Antennule and antenna: Ultimate article of antennule 2.6-2.8 × longer than high. Antennal peduncle relatively slender, not reaching rostral tip. Article 2 with distinct distolateral spine. Antennal scale sharply tapering, 1.6-1.8 × broader than article 5, slightly overreaching article 4 and reaching (usually slightly falling short of) at most midlength of article 5, with no lateral spine. Article 4 with small distomesial spine. Article 5 unarmed, 1.3-1.4 × longer than article 4, breadth slightly less than half height of antennular ultimate article. Flagellum of 11-13 segments slightly falling short of distal end of P1 merus.

Mxp: Mxp1 with bases broadly separated. Mxp3 basis without denticles on convex mesial ridge. Ischium having flexor margin not rounded distally, crista dentata with 28 small denticles. Merus 1.9 × longer than ischium, lateral surface moderately setose, flexor margin not cristate, with or without denticle-like small spine distal to midlength.

P1: Slender, with fine setae, lacking spines; length 5.0-6.2 × (males), 4.2-5.2 × (females) that of carapace. Ischium with short, flattish, laciniate dorsal process, unarmed elsewhere. Merus 1.2-1.3 × longer than carapace. Carpus subcylindrical, 1.2-1.4 × longer than merus. Palm somewhat depressed (height-breadth ratio, 0.7-0.8), 0.8-0.9 × length of carpus, 3.1-4.0 × (males), 3.4-4.5 × (females) longer than broad. Fingers slightly gaping, distally slightly incurved, not spooned; movable finger half as long as palm or slightly less than so; opposable margin with small subtriangular process proximal to opposing low prominence located at midlength of fixed finger.

P2-4: Moderately compressed mesio-laterally, with soft fine setae, along extensor margin in particular. Meri successively shorter posteriorly (P3 merus 0.9 × length of P2 merus, P4 merus 0.8-0.9 × length of P3 merus), subequally broad on P2 and P3, very slightly narrower on P4 than on P3; length-breadth ratio, 3.8-4.6 on P2, 3.6-4.1 on P3, 3.1-3.8 on 4; P2 merus 0.8-0.9 × length of carapace, 1.1-1.2 × length of P2 propodus; P3 merus 1.0-1.1 × length of P3 propodus; P4 merus 0.8- 0.9 × length of P4 propodus; extensor margin smooth or with several crenulations or eminences on P2 and P3, smooth

on P4. Carpi subequal, unarmed, carpus-propodus length ratio, 0.4 on P2, 0.3 on P3 and P4. Propodi shorter on P2 than on subequal P3 and P4; flexor margin with pair of movable slender terminal spines only. Dactyli proportionately broad in lateral view, subequal to length of carpi (dactylus-carpus length ratio, 1.0 × on P2, 1.1 × on P3 and P4), less than half that of propodi (dactylus-propodus length ratio, 0.4 on P2, 0.3-0.4 on P3, 0.3 on P4); flexor margin nearly straight, with 6 or 7 spines often obscured by setae, ultimate small, slender and very close to strongest penultimate spine preceded by 4 or 5 spines successively diminishing, loosely arranged and nearly perpendicular to flexor margin, but proximal-most slightly inclined; antepenultimate spine slightly narrower than (at most three-quarters as broad as) penultimate.

Eggs. Number of eggs carried, 7; size, 0.80 × 0.90 mm - 0.90 × 1.04 mm; 2 eggs, 0.96-1.13 mm.

REMARKS — Uroptychus philippei n. sp., U. bertrandi n. sp., U. sarahae n. sp., U. rutua Schnabel, 2009 and U. toka Schnabel, 2009 are grouped together, sharing the small anterolateral spine of the carapace, the short antennal scale, the P2-4 dactyli with loosely arranged, perpendicularly directed flexor marginal spines, and the pterygostomian flap covered with denticle-like small spines. Uroptychus philippei is different from all of these related species in having the P2-4 dactyli subequal to instead of longer than carpi (the carpus-dactylus length ratio, 1.0 (P2), 1.1 (P3-4) in U. philippei ; 1.1-1.3 (P2-3), 1.2-1.4 (P4) in U. bertrandi ; 1.5 (P2-3), 1.4 (P4) in U. rutua ; 1.3 (P2-3), 1.4 (P4) in U. toka ; 1.1-1.3 (P2-3), 1.2-1.3 (P4) in U. sarahae ) and in having the dorsal surface of the rostrum concave in the proximal half and flattish in the distal half instead of distinctly hollowed out along the entire length. In addition, the dorsal surface of the carapace in U. philippei is usually smooth, occasionally bearing sparse denticles instead of bearing numerous denticle-like small spines around the hepatic region. Uroptychus philippei is distinguished from U. sarahae and U. toka by the P2-4 dactyli bearing the penultimate spine less than 1.3 instead of fully 2 times broader than the antepenultimate spine. Uroptychus bertrandi is distinctive in having proximally strongly inflated eyes, and also is U. rutua in having broad prominences on the gastric region.

Figures

FIGURE 195 Uroptychus philippei n. sp., holotype, ovigerous female 4.0 mm (MNHN-IU-2013-8529). A, carapace and anterior part of abdomen, dorsal. B, same, lateral.C, same, anterior part, lateral. D, same,lateral margin, dorsal. E, sternal plastron, with excavated sternum and basal parts of Mxp1.F, telson.G, left antenna, ventral.H, right Mxp3,ventral.I, same,setae omitted, lateral. Scale bars: 1 mm.

FIGURE 196 Uroptychus philippei n. sp., holotype, ovigerous female 4.0 mm (MNHN-IU-2013-8529). A, right P1, dorsal. B, same, proximal part, lateral. C, same, proximal part, ventral. D, right P2, lateral. E, same, distal part, setae omitted, lateral.F, right P3, lateral.G, right P4, lateral.H, same, distal part,lateral.Scale bars:1 mm.