Uroptychus longicheles 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 : 277-279

Uroptychus longicheles Ahyong & Poore, 2004

Figure 128

Uroptychus longicheles Ahyong & Poore, 2004: 55 , fig. 15.

TYPE MATERIAL — Holotype: Australia, Gifford Guyot , Tasman Sea, 26°44.27’S, 159°28.93’E, 306 m, ov. ♀ ( AM P65826 ). [not examined].

MATERIAL EXAMINED — New Caledonia, Chesterfield Islands. MUSORSTOM 5 Stn DW256, 25°18.0’S, 159°52.70’ E, 290-300 m, 7.X.1986, 1 ♀

1.8 mm (MNHN-IU-2014-16654).

DISTRIBUTION„ Tasman Sea, and now Chesterfield Islands; 290- 306 m.

DIAGNOSIS — Small species. Carapace slightly broader than long (0.9 × as long as broad); greatest breadth 1.3 × distance between anterolateral spines. Dorsal surface with weak depression bordering gastric and cardiac regions; lateral portion of posterior branchial region with low projection around last lateral spine; lateral margins weakly convex, with 5 spines: first anterolateral, distinctly posterior to level of lateral orbital spine, never overreaching that spine, subequal to second and fifth; third ventral to level of second and fourth; fifth more dorsal to this level. Rostrum half as broad as posterior carapace margin. Lateral orbital spine distinctly larger than anterolateral spine. Pterygostomian flap anteriorly angular, produced to sharp spine; surface with small spines. Excavated sternum anteriorly ending in rounded margin, surface ridged in midline. Sternal plastron as long as broad, lateral extremities subparallel between sternites 4 and 7; sternite 3 with 2 tiny submedian spines separated by narrow notch; sternite 4 with anterolateral margin about as long as posterolateral margin. Anterolateral margins of sternite 5 slightly convex, length 0.8 × that of posterolateral margin of sternite 4. Abdominal somite 1 without transverse ridge. Somite 2 tergite 2.4 × broader than long, pleuron anterolaterally and posterolaterally rounded, lateral margins somewhat concave; pleuron of somite 3 posterolaterally blunt. Telson half as long as broad, posterior plate as long as anterior plate, posterior margin barely emarginate. Eyes 1.7 × longer than broad; lateral and mesial margins subparallel, cornea not dilated, more than half length of remaining eyestalk. Ultimate article of antennule 3.2 × longer than high. Antennal article 2 with distinct lateral spine; antennal scale terminating in midlength of article 5; article 4 with distomesial spine; article 5 as long as article 4, breath about half height of antennular ultimate article. Mxp1 with bases broadly separated. Mxp3 basis without denticles on mesial ridge; ischium with flexor margin not rounded distally, crista dentata with obsolescent denticles; merus 2.8 × longer than ischium, with distinct distolateral spine; carpus unarmed. P1 slender, about 7 × longer than carapace; ischium with sharp, triangular dorsal spine, ventromesial margin unarmed; merus 1.7 × longer than carapace; carpus 1.4 × longer than merus; palm 6 × longer than broad, slightly shorter than carpus; fingers one-third length of palm, distally slightly incurved. P2 merus as long as carapace, as well as P3 merus and P2 propodus; length-breadth ratio, 4.0 on P2 and P3 (P4 missing); carpi subequal on P2 and P3, less than one-third (0.28 on P2, 0.25 on P3) length of propodus, slightly more than half length of dactylus; flexor margin of propodus with pair of terminal spines only; dactyli 3 × longer than broad (breadth measured at base), 1.6 × longer than carpi, half length of propodi, flexor margin nearly straight, bearing 7 spines, ultimate slender, penultimate pronouncedly broad and long (fully 3 × broader than ultimate and antepenultimate), remaining spines slender, obliquely directed and loosely arranged.

REMARKS — The rostrum in the present specimen is not normal, very short as displayed by the ovigerous female paratype (MNHN-IU-2014-16386) of U. denticulisquama n. sp. (see above). The P2-3 meri bear 2 small spines on the proximal portion of dorsal crest (P4 missing), a character not possessed by the holotype (rechecked by S. Ahyong, pers. comm). The other features agree very well with the original description.

The sternal plastron, antenna, P1 and P2 dactyli are nearly similar in U. laurentae n. sp., U. longicheles , U. paenultimus Baba, 2005 and U. turgidus n. sp. Uroptychus longicheles differs from U. paenultimus in having the carapace lateral margin with 4 or 5 distinct spines instead of 7 or 8 very small spines, in addition to the anterolateral spine of good size, and in having the posterior branchial region with a low dorsolateral projection instead of being smooth. The differences between U. longicheles and U. laurentae are outlined under the remarks of the latter (see above). Also, the reader is referred to the remarks of U. turgidus for its relationships with U. longicheles (see below).

Figures

FIGURE 128 Uroptychus longicheles Ahyong & Poore, 2004, female 1.8 mm (MNHN-IU-2014-16654). A, carapace and anterior part of abdomen, dorsal. B, same,lateral.C, same,right half,dorsomesial.D, right P2,proximal part,lateral.E, same,distal part,setae omitted,lateral.Scale bars:1 mm.