Uroptychus imparilis, 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 : 232-236

Uroptychus imparilis n. sp.

Figures 105 , 106

Uroptychus scandens Baba 1981: 132 (not Uroptychus scandens Benedict, 1902 ).

TYPE MATERIAL — Holotype: Philippines. MUSORSTOM 1 Stn CP 40, 13°57.4’N, 120°27.8’E, 287- 265 m, 24.III.1976, ov. ♀ 3.8 mm ( MNHN-IU-2013-8565 ) . Paratypes: Philippines. MUSORSTOM 1, collected with holotype 1 ♂ 3.2 mm, 1 ov. ♀ 3.6 mm (MNHN-IU-2014-10143 & MNHN-IU-2014-10144) , 1 ov. ♀ 4.0 mm (MNHN-IU-2014-16579) . MUSORS- TOM 2 Stn CP75, 13°51’N, 120°30’E, 300-330 m, 1.XII.1980, 1 ov. ♀ 3.2 mm (MNHN-IU-2014-16580) . Indonesia, Kai Islands. KARUBAR Stn CP06, 5°49’S, 132°21’E, 298- 287 m, 22.X.1991, 1 ♂ 3.5 mm (MNHN-IU-2014-16582) . Vanuatu. MUSORSTOM 8 Stn CP1025, 17°49.01’S, 168°39.37’E, 385-410 m, 28.IX.1994, 1 ov. ♀ 3.0 mm (MNHN-IU-2014-16583) .

OTHER MATERIAL EXAMINED — Japan, Tosa Bay. On pennatulacean, 24.XII.1959, K. Sakai coll., 1 ov. ♀ (carapace broken), 1 ♀ 3.6 mm ( ZLKU 7466) ; 150 m, 31.I.1959,K.Kurohara coll., 1 ♂ 3.6 mm ( ZLKU 5871) ; IV.1960,K.Sakai coll., 1 ov. ♀ 3.2 mm ( ZLKU 14393) . Southern Kyushu,SOYO-MA- RU Stn 72d, 31°13.6’N, 129°58.5’E, 310 m, 12.II.1959, 2 ♂ 2.7, 3.1 mm, 1 ♀ 3.2 mm ( NSMT) . Hachijo-jima, SOYO-MARU Stn B3, 33°06.5’N, 140°04.8’E, 490-495 m, 12.XII.1963, 1 ♂ 3.7 mm ( NSMT) .

ETYMOLOGY„ From the Latin imparilis (different), suggesting that the species is different from the closest congener U. parisus n. sp. (see below).

DISTRIBUTION„ Philippines, Indonesia, Vanuatu and Japan; 150- 495 m.

SIZE„ Males, 2.7-3.7 mm; females, 3.0- 3.8 mm; ovigerous females from 3.0 mm.

DESCRIPTION„ Small species. Carapace: Broader than long (0.8 × as long as broad); greatest breadth 1.8 × distance between anterolateral spines. Dorsal surface setose laterally, with very small spines on epigastric, hepatic and anterior lateral branchial regions, those on hepatic region somewhat larger. Lateral margins convexly divergent posteriorly, occasionally slightly constricted between hepatic and branchial regions, bearing row of small spines; anterolateral spine much larger than others, directed straight forward, overreaching much smaller lateral orbital spine. Rostrum narrow triangular, with interior angle of 25°; lateral margins feebly concave, with 8-9 denticles; dorsal surface somewhat concave; length slightly smaller than (0.9 ×) breadth, 0.4 × that of remaining carapace, breadth less than half carapace breadth measured at posterior carapace margin; lateral orbital spine slightly anterior to level of anterolateral spine. Pterygostomian flap anteriorly angular, produced to strong sharp spine; surface with small spines on anterior half, including row of spines along anterior part of dorsal margin.

Sternum: Excavated sternum with slightly convex anterior margin; surface smooth, without ridge and central spine, with setae along anterior margin; sternal plastron 0.8 × as long as broad (1.3 × broader than long); anterior margin of sternite 3 broadly and deeply excavated nearly in semicircular shape, with pair of small median spines basally contiguous (one of the spines occasionally missing), anterolateral margin with several small or obsolescent spines. Sternite 4 having anterolateral margin feebly convex, anteriorly produced to distinct spine and followed by a few smaller spines; posterolateral margin 0.7 × as long as anterolateral margin. Anterolateral margin of sternite 5 as long as posterior margin of sternite 4.

Abdomen. Somite 1 gently convex from anterior to posterior. Somite 2 tergite 2.5 × broader than long, pleura similar in males and females, slightly concavely divergent posteriorly, ending in rounded margin. Pleura of somites 3-5 laterally rounded. Telson slightly less than half as long as broad; posterior plate slightly emarginate or feebly convex, 1.7 × longer than anterior plate.

Eyes: Elongate, 1.9-2.1 × longer than broad, reaching or very slightly falling short of rostral tip, lateral margin convex, mesial margin concave. Cornea slightly inflated, very slightly broader than and half as long as remaining eyestalk.

Antennule and antenna: Ultimate article of antennular peduncle 2.7-2.9 × longer than high. Antennal peduncle slightly overreaching rostral tip. Article 2 with strong distolateral spine. Antennal scale articulated with article 2, ending in midlength of article 5, laterally with 1 or 2 spines; breadth 1.3-1.4 × that of article 5. Article 3 distomesially rounded or produced to small spine. Article 4 with distinct distomesial spine. Article 5 with small distomesial spine, length 1.5 × that of article 4, breadth 0.4-0.5 × height of ultimate article of antennule. Flagellum of 8-10 segments ending in midlength of P1 merus.

Mxp: Mxp1 with bases broadly separated. Mxp3 with long setae. Basis with 1 distal denticle on mesial ridge. Ischium with small spine lateral to distal end of flexor margin, crista dentata with a few to several obsolescent denticles on proximal half. Merus 2.5 × length of ischium, ridged along flexor margin, not well compressed; with 3 spines on distal third of flexor margin and 2 distolateral spines. Carpus unarmed.

P1: Slender, subcylindrical, 5.7-6.6 × (males), 4.4-6.8 × (females) longer than carapace. Ischium dorsally with basally broad, depressed, bifurcate short spine, ventromesially unarmed. Merus 1.5 × longer than carapace, dorsally bearing 2 rows of spines: 1 row along mesial margin and another row of smaller (some bifurcated) spines directly dorsolateral

to it). Carpus 1.3-1.4 × longer than merus, unarmed. Palm 4.1-5.0 × (males), 6.4-6.6 (females) as long as broad, slightly (females) or distinctly (males) broadened distally, length 0.9 × that of carpus. Fingers relatively narrow distally, strongly gaping in proximal two-thirds in males, weakly so in proximal third in females; opposable margins fitting to each other in distal two-thirds (females) or in distal third (males) when closed, with row of denticles; movable finger 0.4 × length of palm, with obtuse process at midpoint of gaping portion.

P2-4: Thickly setose like P1. Meri successively shorter posteriorly (P3 merus 0.9 × length of P2 merus, P4 merus 0.8 × length of P3 merus), slightly broader on P3 and P4 than on P2, or slightly broader on P3 than on P2 and P4; lengthbreadth ratio, 4.1-4.2 on P2, 3.4 on P3, 2.9-3.0 on P4; dorsal margin with 7-9 small spines on P2, 6-7 on P3, unarmed on P4; P2 merus subequal to length of carapace, 1.3-1.4 × length of P2 propodus; P3 merus 1.3 × length of P3 propodus; P4 merus 1.2-1.3 × length of P4 propodus. Carpi successively shorter posteriorly; carpus-propodus length ratio, 0.6 on P2, 0.5 on P3 and P4. Propodi successively shorter posteriorly; flexor margin straight in lateral view, with pair of small terminal spines only. Dactyli subequal on P2-4; dactylus-carpus length ratio, 0.5-0.6 on P2, 0.6-0.7 on P3, 0.6-0.8 on P4; dactylus-propodus length ratio, 0.3 on P2, 0.3-0.4 on P4; truncate, bearing 7 slender spines obscured by setae on P2 and P3, 6 spines on P4, 3 or 4 of these located on terminal margin, remainder perpendicular to flexor margin, terminal spine smaller.

Eggs. Number of eggs carried, about 40; size, 0.63 × 0.68 mm - 0.61 × 0.71 mm.

REMARKS — The material registered under ZLKU 5871 contains three specimens. One is identified as U. imparilis and the other two, with the label “associated with a pennatulacean,” are Uroptychus scandens . The materials reported under U. scandens by Baba (1981) are referable to U. imparilis .

This species shares truncate dactyli of P2-4 with U. articulatus n. sp., U. parisus n. sp. and U. scandens Benedict, 1902 . Their relationships are discussed under U. scandens (see below).

Figures

FIGURE 105 Uroptychus imparilis n. sp., holotype, ovigerous female 3.8 mm (MNHN-IU-2013-8565). A, carapace, dorsal. B, same, anterior part of abdomen included, lateral.C, anterior part of carapace,dorsal. D, anterior part of sternal plastron, with excavated sternum and basal parts of Mxp1.E, right pleura of abdominal somites 2-5, dorsolateral.F, telson.G, right antenna,ventral.H, right Mxp3,ventral, setae omitted.I, same, lateral.Scale bars: 1 mm.

FIGURE 106 Uroptychus imparilis n. sp.; A-C, E-I, holotype, ovigerous female 3.8 mm (MNHN-IU-2013-8565); D, male paratype 3.2 mm (MNHN-IU-2014-10143).A, left P1,setae omitted,dorsal.B, same,proximal part,ventral.C, same,lateral.D,left fingers,setae omitted, dorsal. E, right P2, setae omitted, lateral.F, same,distal part, lateral.G, right P3, lateral.H, same, distal part, lateral.I, right P4,lateral. J, same,distal part, lateral. Scale bars:1 mm.