Uroptychus granulipes, 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 : 229-232

Uroptychus granulipes n. sp.

Figures 103 , 104

TYPE MATERIAL — Holotype: New Caledonia, Norfolk Ridge. NORFOLK 2 Stn DW 2060, 24°39.84’S, 168°38.50’E, 582- 600 m, 25.X.2003, ♀ 7.0 mm ( MNHN-IU-2014-16578 ).

ETYMOLOGY„ From the Latin granulus (a small grain) plus pes (foot), alluding the granulose P1 merus and carpus.

DISTRIBUTION„ Norfolk Ridge; 582- 600 m.

DESCRIPTION„ Carapace: As long as broad; greatest breadth 1.6 × distance between anterolateral spines. Dorsal surface smooth and glabrous, slightly convex from anterior to posterior, with very feeble depression between gastric and cardiac regions. Lateral margins somewhat convex posteriorly, finely denticulate on anterior branchial margin, feebly ridged along posterior portion behind pterygostomian flap; anterolateral spine prominent, directed forward, situated directly lateral to (not posterior to level of) smaller lateral orbital spine, extending far beyond that spine. Rostrum directed somewhat ventrally, elongate triangular, with interior angle of 27°, slightly less than half length of rostrum, breadth half carapace breadth measured at posterior carapace margin; dorsal surface moderately concave. Pterygostomian flap anteriorly roundish, produced to sharp spine, surface smooth.

Sternum: Excavated sternum anteriorly produced to spine, slightly ridged in midline on surface. Sternal plastron slightly broader than long, successively broader posteriorly. Sternite 3 depressed well; anterior margin deeply excavated with deep, narrow median sinus flanked by sharp, incurved spine, lateral end sharply produced straight forward. Sternite 4 having anterolateral margin convex, anteriorly angular, slightly more than 1.5 × length of posterolateral margin. Anterolateral margin of sternite 5 anteriorly convex, 1.2 × longer than posterolateral margin of sternite 4.

Abdomen: Tergites smooth, barely setose. Somite 1 strongly convex from anterior to posterior. Somite 2 tergite 2.8 × broader than long; pleuron anterolaterally and posterolaterally blunt angular, lateral margin weakly concave and slightly divergent posteriorly. Pleura of somites 3 and 4 laterally angular. Telson half as long as broad; posterior plate concave on posterior margin, length 1.4 × that of anterior plate.

Eye: Slightly less than twice as long as broad, somewhat overreaching midlength of rostrum, mesial and lateral margins slightly concave. Cornea slightly inflated, more than half as long as remaining eyestalk.

Antennule and antenna: Ultimate article of antennular peduncle 2.3 × longer than high. Antennal peduncle relatively slender, slightly overreaching cornea. Article 2 with small distolateral spine. Antennal scale about twice as broad as article 5, slightly falling short of distal end of article 5, lateral margin with sparse setae. Article 4 with distinct distomesial spine.

Article 5 unarmed, length slightly more than twice as long as article 4, breadth 0.7 × height of antennular ultimate article. Flagellum consisting of 22-24 segments, reaching distal end of P1 merus.

Mxp: Mxp1 with bases separated. Mxp3 barely setose on lateral surface. Basis with 3 denticles on mesial ridge. Ischium with 25 distally diminishing denticles on crista dentata, flexor margin not rounded distally. Merus unarmed, 1.8 × as long as ischium; flexor margin not cristate but somewhat roundly ridged, with a few eminences. Carpus unarmed.

P1: Relatively massive, bearing short, fine setae on fingers, barely setose elsewhere, granulose on ischium, merus and carpus. Ischium dorsally with basally broad, long spine, ventromesially with well-developed subterminal spine. Merus 1.1 × longer than carapace. Carpus 1.2 × longer than merus. Palm 2.8 × longer than broad, as long as carpus. Fingers slightly curving ventrally, distally strongly incurved, crossing when closed; movable finger half as long as palm, opposable margin with 2 low processes proximal to midlength; opposable margin of fixed finger with 2 prominences, proximal one fitting to between 2 processes on movable finger.

P2-4: Slender, sparsely with fine setae on distal articles. Meri moderately compressed mesio-laterally, successively shorter posteriorly (P3 merus 0.9 × length of P2 merus, P4 merus 0.8 × length of P3 merus), equally broad on P2-4; lengthbreadth ratio, 5.4-5.9 on P2, 4.9-5.4 on P3, 3.8-4.2 on P4; P2 merus as long as carapace, 1.3 × longer than P2 propodus; P3 merus about as long as P3 propodus; P4 merus 0.8 × length of P4 propodus; dorsal margin with obsolescent denticles on proximal half. Carpi subequal on P2 and P3, P4 carpus 0.9 × length of P3 carpus; length 0.5 × that of propodus on P2 and P3, 0.4 × on P4. Propodi subequal in length on P3 and P4 and slightly shorter on P2; flexor margin ending in pair of spines preceded by 9 or 10 spines on P2, 6 on P3, 4 on P4. Dactyli shorter than carpi (dactylus-carpus length ratio, 0.8 on P2, 0.9 on P3 and P4), 0.4 × as long as propodi on P2-4; flexor margin curving, setose, with 11-12 slightly inclined, loosely arranged triangular spines successively diminishing toward proximal end of article; extensor margin with fringe of setae.

REMARKS — The new species is very close to U. inermis n. sp. in nearly all aspects. Their relationships are discussed under the remarks of that species (see below).

The shape of the carapace which bears strong anterolateral spines, and the spination of P2-4 displayed by this species resemble those of U. brucei Baba, 1986a and U. maori Borradaile, 1916 . Uroptychus granulipes is differentiated from U. brucei by the carapace dorsal surface that is smooth instead of granulose; the anterolateral spine is situated directly lateral to instead of posterior to the position of lateral orbital spine; the carapace lateral margin is almost smooth instead of distinctly ridged along the posterior portion; the P1 merus and carpus are granulose instead of smooth; the antennal article 5 is unarmed instead of bearing a distinct spine; and the dactylus-carpus length ratio is 0.8 on P2, 0.9 on P3 and P4, instead of 0.6 on P2 and P3, 0.7 on P4. Uroptychus granulipes is different from U. maori (see below) in having the carapace dorsal surface smooth instead of granulose, bearing a ridge along the posterior part of lateral margin, and in having the pterygostomian flap smooth instead of granulated on the surface.

Figures

FIGURE 103 Uroptychus granulipes n. sp., holotype, female 7.0 mm (MNHN-IU-2014-16578). 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.H, left P1, proximal part, ventral. I, same, dorsal. Scale bars: A-G, 1 mm; H, I, 5 mm.

FIGURE 104 Uroptychus granulipes n. sp.,holotype,female 7.0 mm (MNHN-IU-2014-16578).A, left P2,lateral.B, same,distal part,setae omitted,lateral.C, left P3,setae omitted, lateral. D, left P4, setae omitted, lateral. Scale bars: 1 mm.