Uroptychus longvae 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 : 283-286

Uroptychus longvae Ahyong & Poore, 2004

Figure 131

Uroptychus longvae Ahyong & Poore, 2004: 58 , fig. 16.

TYPE MATERIAL — Holotype: Australia, 342 km west of Cape Wiles, Great Australian Bight , South Australia, 34°56’S, 133°20’E, 805-816 m, ov. female ( SAMC C6064 ). [not examined].

MATERIAL EXAMINED — New Caledonia, Norfolk Ridge.NORFOLK 2 Stn DW2070, 25°22.97’S, 168°57.12’E, 630-1150 m, 26.X.2003, 1 ♂ 5.0 mm (MNHN-IU-2014-16697).

DISTRIBUTION„ Great Australian Bight, and now Norfolk Ridge; 630-1150 m.

DESCRIPTION„ Medium-sized species. Carapace: Broader than long (0.8 × as long as broad), greatest breadth 1.8 × distance between anterolateral spines. Dorsal surface unarmed, covered with short fine setae, moderately convex from anterior to posterior, without groove or depression. Lateral margins convexly divergent, bearing row of short, oblique, setiferous ridges; anterolateral spine strong, overreaching acuminate lateral orbital angle. Rostrum narrow triangular, with interior angle of ca. 20°, straight horizontal on ventral surface; dorsal surface flattish; length about half that of remaining carapace, breadth one-third carapace breadth at posterior carapace margin. Lateral limit of orbit acuminate without distinct spine, situated at same level as anterolateral spine, and separated from that spine by full breadth of cornea. Pterygostomian flap with somewhat angular anterior margin without distinct spine, surface smooth.

Sternum: Excavated sternum with anterior margin slightly convex between bases of Mxp1, surface with low ridge in midline. Sternal plastron 1.4 × broader than long (three-quarters as long as broad), lateral extremities convexly divergent posteriorly. Anterior margin of sternite 3 excavated in broad V-shape, without spines but obsolescent median notch, lateral ends bluntly angular. Sternite 4 with anterolateral margin anteriorly convex with obsolescent denticles, twice as long as posterolateral margin. Anterolateral margin of sternite 5 anteriorly rounded, 1.5 × longer than posterolateral margin of sternite 4.

Abdomen: Smooth, with fine setae. Somite 1 without transverse ridge. Somite 2 tergite 3.3 × broader than long; pleuron rounded on anterolateral end, bluntly angular on posterolateral end, lateral margin concavely divergent posteriorly. Pleuron of somite 3 tapering. Telson slightly less than half as long as broad; posterior plate 1.2 × longer than anterior plate, posterior margin distinctly emarginate.

Eye: Short (1.6 × longer than broad), barely reaching midlength of rostrum, slightly narrowed distally. Cornea more than half as long as remaining eyestalk.

Antennule and antenna: Ultimate article of antennule 2.9 × longer than high. Antennal peduncle overreaching cornea. Article 2 without distinct lateral spine. Antennal scale more than 2 × as broad as article 5, ending in midlength of that article. Article 5 1.3 × longer than article 5, breadth 0.6 × height of antennular basal article; no spine on articles 4 and 5 but tuft of setae on each mesio-distoventral margin; flagellum of 11-12 segments.

Mxp: Mxp1 with bases broadly separated. Mxp3 basis with obsolescent denticle. Ischium with flexor margin not rounded distally, crista dentata with numerous, very small denticles. Merus 2 × longer than ischium, unarmed. Carpus also unarmed.

P1: Missing.

P3-4: P2 missing; left P3, left P4, and right P4 available, relatively thick, not strongly compressed mesio-laterally, sparingly bearing soft setae. P3 merus 0.9 × length of P3 propodus; P3 merus 0.9 × length of P3 propodus; P4 merus 0.7 × length of P3 merus, 0.7 × length of P4 propodus; length-breadth ratio, 3.3 on P3, 2.6 on P4. P4 carpus 0.9 length of P3 carpus, carpus-propodus length ratio, 0.4 on P3 and P4. Propodi without flexor marginal spine, slightly longer on P3 than on P4. Dactyli subequal on P3 and P4, strongly curving at proximal quarter of length; dactylus-carpus length ratio, 1.7 on P3, 1.5 on P4; dactylus-propodus length ratio, 0.6 on P3, 0.7 on P4; flexor margin thickly setose, with row of 20 subtriangular spines successively diminishing toward proximal end of article, more or less close to one another, somewhat obliquely directed (proximal spines perpendicular to margin), all obscured by setae; ultimate spine slightly larger than penultimate.

REMARKS — The specimen examined agrees well with the description of the holotype, except that the P3 carpus is relatively short.

The species is very similar to U. setosidigitalis Baba, 1977 from off Midway Island and U. onychodactylus Tirmizi, 1964 from the Maldives. In addition to the differences noted by Ahyong & Poore (2004), U. longvae is distinguished from these two species by the anterolateral spine of the carapace that is strong rather than small, extending far beyond instead of never overreaching the acuminate lateral orbital angle. Examination of the type material of Uroptychus onychodactylus shows that the P2-4 dactyli are more strongly curved ( Figure 132 ), a distinctive difference from U. longvae and U. setosidigitalis .

Uroptychus longvae also resembles U. foulisi Kensley, 1977 in having no flexor marginal spine on the P2-4 propodi, in having proximally diminishing flexor marginal spines on the dactyli, and in having the anterolateral spine of the carapace distinctly larger than the lateral orbital spine. Uroptychus foulisi is known only from the brief description of the type material from the western Indian Ocean, but is clearly different from U. longvae in having distinct carapace lateral spines in addition to the anterolateral one and in having fewer (8 versus 18-20), more obliquely directed flexor marginal spines on the P2-4 dactyli.

Figures

FIGURE 131 Uroptychus longvae Ahyong & Poore,2004,male 5.0 mm (MNHN-IU-2014-16697).A, carapace and anterior part of abdomen, dorsal.B, same,lateral.C, lateral margin of carapace,right,dorsal. D, sternal plastron,with excavated sternum and basal parts of Mxp1. E, left antenna, ventral. F, right Mxp3, ventral.G, same, lateral.H, left P3, lateral. I, same, distal part, setae omitted, lateral.J, left P4, setae omitted, lateral.Scale bars: 1 mm.

FIGURE 132 Uroptychus onychodactylus Tirmizi, 1964, holotype, ovigerous female 7.5 mm (BMNH 1966.2.3.41). A, anterior part of carapace, dorsal. B, right P2, distal part,lateral.C, right P3,distal part,lateral.Scale bar:1 mm.