Uroptychus dejouanneti, 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 : 159-163

Uroptychus dejouanneti n. sp.

Figures 65 , 66

Uroptychus gracilimanus Baba 1969: 45 , figs 3, 4; 1988: 35; 2005: 36. — Baba et al. 2009: 44, figs 36-37 (not U.gracilimanus ( Henderson, 1885)) .

TYPE MATERIAL — Holotype: Indonesia, Tanimbar Islands. KARUBAR Stn CP38, 7°40’S, 132°27’E, 620-666 m, with Acanella sp. ( Isididae ) and Thouarella sp. ( Primnoidae ), 28.X.1991, ov. ♀ 6.9 mm ( MNHN-IU-2013-8538 ) . Paratypes: Indonesia, Kai Islands. KARUBAR Stn CP19, 5°15’S, 133°01’E, 605- 576 m, on gorgonacean, 25.X.1991, 2 ov. ♀ 6.9 mm, 7.5 mm (MNHN-IU-2013-8535) . – Stn CP20, 5°15’S, 132°59’E, 769-809 m, Chrysogorgiidae gen. sp. ( Calcaxonia ), 25.X.1991, 3 ♂ 6.8, 6.8, 7.6 mm, 6 ov. ♀ 7.2-7.8 mm (MNHN-IU-2013-8536) . – Stn CC21, 5°14’S, 133°00’E, 688-694 m, 25.X.1991, 2 ♂ 7.6, 7.8 mm, 4 ov. ♀ 6.0-8.0 mm, 2 ♀ 4.8, 6.8 mm (MNHN-IU-2013-8537) . Indonesia, Tanimbar Islands. KARUBAR Stn CP38, 7°40’S, 132°27’E, 620-666 m, Acanella sp. ( Isididae ) + Thouarella sp. ( Primnoidae ), 28.X.1991, 5 ♂ 5.7-7.8 mm, 5 ov. ♀ 6.7-7.6 mm, 3 ♀ 5.6-7.8 mm, 1 ♂ 7.6 mm (MNHN-IU-2014-10140, MNHN-IU-2014-10141, MNHN-IU-2014-10142, MNHN-IU-2014-16379) . – Stn CP39, 7°47’S, 132°26’E, 477- 466 m, 28.X.1991, 1 ♂ 8.6 mm (MNHN-IU-2013-8539) . – Stn CC57, 8°19’S, 131°53’E, 603-620 m, 31.X.1991, 3 ♂ 5.0- 6.2 mm, 1 ov. ♀ 6.2 mm, 1 ♀ 7.2 mm (MNHN-IU-2013-8540) . – Stn CC58, 8°19’S, 132°02’E, 457-461 m, 31.X.1991, 1 ♂ 7.1 mm ( MNHN- IU-2013-8541) .

ETYMOLOGY„ Named after Jean-Françoise Dejouannet, artist at the Paris Museum, for his friendship.

DISTRIBUTION„ Indonesia (Kai Islands, Tanimbar Islands, Molucca Sea off west coast of Halmahera), Philippines (east

of Zamboanga), Taiwan and East China Sea; 441-1060 m.

SIZE„ Males 5.0- 8.6 mm; females, 4.8-8.0 mm; ovigerous females from 6.0 mm.

DESCRIPTION„ Medium-sized species. Carapace: As long as broad; greatest breadth 1.6-1.8 × distance between anterolateral spines. Dorsal surface smooth, glabrous and unarmed, anteriorly somewhat inflated in profile, with or without faint depression between gastric and cardiac regions. Lateral margins somewhat convex and divergent posteriorly, with row of obsolescent short ridges along anterior half of branchial margin; ridged along posterior half; anterolateral spine small, varying from barely to fully reaching tiny lateral orbital spine where present, situated distinctly posterior to level of that spine. Rostrum 0.8-1.0 × as long as broad, triangular with interior angle of 24-30°, straight horizontal or curving slightly ventrally; length 0.3-0.4 × that of remaining carapace, breadth slightly less than half carapace breadth measured at posterior carapace margin; lateral margins slightly concave; dorsal surface slightly concave at base. Lateral orbital spine small, often obsolescent or absent. Pterygostomian flap anteriorly roundish, bearing very small spine.

Sternum: Excavated sternum anteriorly broad triangular, ending in small spine, surface with spine in center. Sternal plastron 0.9-1.0 × as long as broad, lateral extremities between sternites 4 and 7 divergent posteriorly. Sternite 3 moderately depressed, with well-excavated anterior margin bearing 2 distinct submedian spines flanking narrow and shallow or U-shaped sinus, laterally angular. Sternite 4 having convex anterolateral margin, with short spines on anterior half (anterior 2 often of good size and others obsolescent), about 1.6-1.8 × length of posterolateral margin. Anterolateral margins of sternite 5 somewhat convexly divergent posteriorly, slightly longer than posterolateral margin of sternite 4.

Abdomen: Tergites smooth and glabrous. Somite 1 without transverse ridge. Somite 2 tergite 2.3-2.5 × broader than long; pleuron posterolaterally ending in rounded terminus, lateral margin somewhat concavely divergent posteriorly. Pleura of somites 3 and 4 laterally rounded. Telson very slightly more than half (0.53-0.58 x) as long as broad; posterior plate moderately emarginate or feebly concave on posterior margin, length 1.6-1.8 × that of anterior plate.

Eye: Short relative to breadth (1.7-1.8 × longer than broad), slightly concave on mesial margin, slightly convex on lateral margin, slightly falling short of rostral tip. Cornea not dilated, about half length of remaining eyestalk.

Antennule and antenna: Ultimate article of antennular peduncle 2.3-2.7 × longer than high. Antennal peduncle overreaching cornea, reaching rostral tip. Article 2 distolaterally acuminate or with very tiny spine. Antennal scale 1.5- 1.7 × broader than article 5, usually slightly falling short of midlength of, rarely reaching point three-quarters of article 5. Distal 2 articles unarmed; article 5 1.6-1.8 × longer than article 4, breadth slightly smaller than height of ultimate antennular article. Flagellum of 18-20 segments fully or barely reaching distal end of P1 merus.

Mxp: Mxp1 with bases close to each other. Mxp3 spineless on merus and carpus. Basis with 3 denticles on mesial ridge. Ischium with 20-28 denticles on crista dentata, flexor margin not rounded distally. Merus 2.3 × longer than ischium, relatively thick mesio-laterally, flexor margin sharply ridged.

P1: Slender (male palm in large specimens massive, broader than distance between anterolateral spines of carapace), unarmed, sparsely setose on fingers, glabrous elsewhere; length 4.7-5.5 × (males), 4.9-5.3 × (females) that of carapace. Ischium with basally broad, low and blunt dorsal spine often obsolescent, ventrally unarmed. Merus 1.1-1.3 × longer than carapace. Carpus 1.3-1.4 × longer than merus. Palm 2.2-3.2 × (males; slender in small specimens), 3.6-3.8 × (females) longer than broad, 0.7-0.9 × as long as carpus. Fingers proportionately broad, gaping in proximal half in males, not gaping in females, ending in incurved tips, feebly crossing; movable finger 0.6-0.7 × length of palm; opposable margin of movable finger with broad proximal process low in females, high and 2-toothed in males.

P2-4: Slender, with sparse long setae. Meri successively shorter posteriorly (P3 merus 0.9 × length of P2 merus, P4 merus 0.9 × length of P3 merus), breadths subequal on P2-4; length-breadth ratio 5.7-6.4 on P2, 4.9-5.6 on P3, 4.5-5.5 on P4; dorsal and ventrolateral margins unarmed; P2 merus 0.8-0.9 × length of carapace, 1.2 × length of P2 propodus; P3 merus as long as P3 propodus; P4 merus 0.9 × length of P4 propodus. Carpi subequal or shorter on P2 than on subequal P3 and P4; carpus-propodus length ratio, 0.4-0.5 on P2 and P3, 0.4 on P4. Propodi successively slightly longer posteriorly; flexor margin nearly straight, with 6-8 basally articulated, long spines on two-thirds to four-fifths of length on P2, 6 or 7 spines on P3, 5 or 6 spines more distal on P4, terminal spine single, located very close to distal end and mesial to flexor midline. Dactyli curving at middle, length 0.4 × length of propodi on P2-4; dactylus-carpus length ratio, 0.8-0.9 on P2, 0.8-1.0 on P3, 1.0 on P4; flexor margin with 8-10 sharp, obliquely directed spines, distal 4 or 5 subequal, remaining spines successively diminishing toward base of article.

Eggs. Up to 40 eggs carried; size, 0.92 × 1.25 mm - 1.01 × 1.29 mm.

Color. A specimen from Taiwan reported under U. gracilimanus was illustrated by Baba et al. (2009).

PARASITES — Three males of the specimens from KARUBAR Stn CC21, CC57 and CC58 and one female from Stn CP38 each bear an externa of rhizocephalan parasite.

REMARKS — This species is so similar to U. gracilimanus ( Henderson, 1885) that careful examination should be paid to the spination of the P2-4 dactyli: the ultimate of the flexor spines in the new species is subequal to, instead of distinctly narrower than, the penultimate spine as in U. gracilimanus (see below). The material reported under U. gracilimanus ( Henderson, 1885) by Baba (1969; 1988) and Baba et al. (2009) are now referred to U. dejouanneti . Uroptychus dejouanneti resembles U. stenorhynchus n. sp. Their relationships are discussed under that species (see below).

Molecular data provided by L. Corbari (personal comm.) suggest that the specimens MNHN-IU-2014-10141 and IU-2014-10142 are different from each other at a specific level (the genetic divergence between the two specimens is 7.2 % (COI)), but no morphological differences were found.

Figures

FIGURE 65 Uroptychus dejouanneti n.sp.,holotype,ovigerous female 6.9 mm (MNHN-IU-2013-8538).A, carapaceand anterior part of abdomen, dorsal. B, same, lateral. C, anterior part of cephalothorax, showing anterolateral spine, anterior part of pterygostomian flap and antenna, lateral. D, sternal plastron, with excavated sternum and basal parts of Mxp1. E, telson. F, right antenna, ventral. G, right Mxp3,setae omitted,ventral.H, same,lateral. Scale bars: 1 mm.

FIGURE 66 Uroptychus dejouanneti n. sp., holotype,ovigerous female 6.9 mm (MNHN-IU-2013-8538).A, left P1, dorsal.B, same,proximal part, ventral. C, same, lateral. D, left P2, lateral. E, same,distal part, setae omitted, lateral. F, left P3,setae omitted,lateral.G, same,distal part, setae omitted, lateral.H, left P4,setae omitted, lateral. I, same, distal part, setae omitted,lateral.Scale bars:1 mm.