Uroptychus multispinosus Ahyong & Poore, 2004

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 : 326-329

Uroptychus multispinosus Ahyong & Poore, 2004

Figures 156 , 157

Uroptychus multispinosus Ahyong & Poore, 2004: 60 , fig. 17.

TYPE MATERIAL — Holotype: Australia, E of Southport , Queensland, 318 m, female ( AM P31415 ). [not examined].

MATERIAL EXAMINED — New Caledonia, Norfolk Ridge.CHALCAL 2 Stn DW74, 24°49.36’S, 168°38.38’E, 650 m, 29.X.1986, 1 ♂ 3.2 mm ( MNHN- IU-2014-16743) .

DISTRIBUTION„ Southern Queensland, and now New Caledonia; 318- 650 m.

DESCRIPTION„ Small species. Carapace: As long as broad; greatest breadth 1.6 × distance between anterolateral spines. Dorsal surface convex from anterior to posterior, with feeble depression between gastric and cardiac regions, bearing scattered short setae. Lateral margins posteriorly divergent but slightly convex on posterior branchial region; anterolateral spine small, barely reaching tip of lateral orbital spine, followed by 5 or 6 very small, obsolescent spines along entire margin; no ridge along posterior lateral margin. Rostrum narrow triangular, with interior angle of 15°, horizontal on ventral surface, dorsally concave, laterally with small subterminal spine on each side; length about half that of remaining carapace, breadth about half carapace breadth at posterior carapace margin. Lateral orbital spine as large as anterolateral spine, situated slightly anterior to level of, and separated from that spine by its basal breadth. Pterygostomian flap with spinules on surface, anteriorly angular, produced to small spine.

Sternum: Excavated sternum moderately convex on anterior margin, surface with distinct ridge in midline. Sternal plastron somewhat broader than long. Sternite 3 shallowly depressed; anterior margin shallowly excavated, with broad median notch flanked by very small spine, lateral end with a few very small spines. Sternite 4 anterolaterally blunt angular, anterolateral margin smooth, more than twice as long as posterolateral margin. Sternite 5 slightly broader than sternite 4, anterolateral margins anteriorly convex, subparallel, much longer than posterolateral margin of sternite 4. Sternites 6 and 7 subequal in breadth, broader than sternite 5.

Abdomen: More setose than carapace. Somite 1 moderately convex from anterior to posterior. Somite 2 tergite 2.4 × broader than long; pleuron posterolaterally blunt; lateral margin slightly concave and somewhat divergent posteriorly. Pleuron of somite 3 with blunt lateral terminus. Telson slightly less than half as long as broad; posterior plate somewhat concave on posterior margin, length 0.8 × that of anterior plate.

Eye: 1.8 × longer than broad, slightly overreaching midlength of rostrum, somewhat narrowed distally. Cornea half as long as remaining eyestalk.

Antennule and antenna: Ultimate article of antennular peduncle 2.9 × longer than high. Antennal peduncle relatively short, terminating in distal end of cornea. Article 2 with sharp lateral spine. Antennal scale overreaching peduncle by full length of article 5, breadth 1.7 × that of article 5. Distal 2 articles short relative to breadth, each with distinct distomesial spine; article 5 as long as article 4; breadth 0.7 × height of ultimate antennular article. Flagellum of 9 segments far falling short of distal end of P1 merus.

Mxp: Mxp1 with bases broadly separated. Mxp3 basis without distinct denticles on mesial ridge. Ischium with very small denticles on crista dentata, bearing tuft of setae lateral to rounded distal end of flexor margin. Merus twice as long as ischium, flattish on mesial face; flexor margin ridged, with 2 or 3 small spines on distal third; distolateral spine short and small. Carpus also with distolateral spine.

P1: 5.7 × longer than carapace, setose, relatively massive. Ischium with well-developed distodorsal spine; ventromesial margin with 2 or 3 small denticle-like processes on proximal portion, lacking subterminal spine. Merus with granulate scale-like ridges supporting setae on dorsal surface and tubercles on proximal mesial portion; length 1.1 × that of carapace. Carpus 1.1 × longer than merus, ventrally bearing small distolateral spine. Palm unarmed, about 3 × longer than broad, distally somewhat broader, 1.2 × longer than carpus. Fingers stout, distally crossing when closed. Movable finger falling short of distal end of fixed finger when closed, opposable margin with median process fitting to between 2 low processes on opposite fixed finger; length slightly less than half (0.45) that of palm.

P2-4: Broad relative to length, moderately setose. Meri successively shorter posteriorly (P3 merus 0.9 × length of P2 merus, P4 merus 0.9 × length of P3 merus), equally broad on P2 and P3, slightly narrower on P4 (P4 merus 0.9 × as broad as P3); length-breadth ratio, 2.8 on P2, 2.9 on P3, 2.5 on P4; dorsal margin with a few small proximal spines distinct on P2 and P3, obsolescent on P4. P2 merus 0.7 × length of carapace, subequal to length of P2 propodus; P3 merus 0.9 × length of P3 propodus; P4 merus 0.8 length of P4 propodus. Carpi successively slightly shorter posteriorly; distinctly shorter than dactyli, carpus-dactylus length ratio, 0.9 on P2, 0.7 on P3 and P4; carpus-propodus length ratio, 0.4 on P3 and P4. Propodi subequal on P3 and P4, shorter on P2 (P2 propodus 0.8 × length of P3 propodus); flexor margin nearly straight, ending in pair of spines preceded by 6 spines on P2 and P3, 5 spines on P4. Dactyli slender relative to propodi, length more than half (0.52 on P2, 0.53 on P3, 0.56 on P4) that of propodus; dactylus-carpus length ratio, 1.2 on P2, 1.4 on P3, 1.5 on P4; flexor margin nearly straight on P2, slightly curving on P3, more distinctly so on P4, bearing 7 spines, ultimate spine slender and very close to penultimate, 2 proximal spines small and slender and strongly inclined, 4 other spines strong, somewhat inclined, and widely spaced.

REMARKS — The present specimen agrees with the original description of U. multispinosus , with only small differences: the dorsal margins of P2 and P3 meri bear small spines instead of being unarmed and the lateral marginal spines of the carapace are very small and obsolescent instead of small and distinct. These difference are here regarded as individual variations.

This species strongly resembles U. vicinus n. sp. Their relationships are discussed under the remarks of that species (see below).

Figures

FIGURE 156 Uroptychus multispinosus Ahyong & Poore,2004,male 3.2 mm (MNHN-IU-2014-16743).A,carapace and anterior part of abdomen, proximal part of P1 included, dorsal. B, same, lateral. C, lateral margin of carapace, dorsal. D, sternal plastron, with excavated sternum and basal parts of Mxp1. E, left antenna, ventral. F, right Mxp3, ventral.G, left Mxp3, lateral. H, left P1, proximal part, ventral.I, right P1, dorsal.Scale bars:1 mm.

FIGURE 157 Uroptychus multispinosus Ahyong & Poore, 2004,male 3.2 mm (MNHN-IU-2014-16743).A, left P2,lateral.B, same,distal part, setae omitted, lateral.C, left P3,setae omitted,lateral. D, same, distal part, setae omitted, lateral. E, left P4, setae omitted, lateral.Scale bars:1 mm.