Uroptychus kareenae, 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 : 245-249

Uroptychus kareenae n. sp.

Figures 111 , 112

TYPE MATERIAL — Holotype: Solomon Islands. SALOMON 1 Stn DW 1775, 08°13’S, 160°42’E, 498-600 m, 28.IX.2001,

1 ♂ 4.1 mm ( MNHN-IU-2012-692 ).

DISTRIBUTION„ Solomon Islands, in 498- 600 m.

ETYMOLOGY — Named for Kareen Schnabel for her contributions to the knowledge of squat lobster taxonomy and distribution.

DESCRIPTION„ Small species. Carapace: Slightly broader than long (0.9 × as long as broad); greatest breadth 1.9 × distance between anterolateral spines. Dorsal surface smooth and glabrous, feebly convex from anterior to posterior, depressed between gastric and cardiac regions. Lateral margins divergent posteriorly to point at anterior end of branchial region, with small acuminate eminence at midpoint between, then subparallel posteriorly; feebly ridged along posterior part of branchial margin; anterolateral spine overreaching lateral orbital spine, more or less close to and situated directly lateral to that spine; branchial margin with well-developed spine at anterior end, followed by 5 or 6 posteriorly diminishing spines. Rostrum narrow triangular, with interior angle of 23°, length half that of carapace, breadth slightly more than one-third carapace breadth at posterior carapace margin; dorsal surface somewhat concave. Pterygostomian flap anteriorly moderately angular, ending in distinct spine.

Sternum: Excavated sternum sharp triangular on anterior margin, with weak ridge in midline on surface. Sternal plastron 0.9 × as long as broad, lateral extremities slightly divergent posteriorly. Sternite 3 well depressed, anterolaterally sharp angular, anterior margin semicircular (shallowly), with V-shaped median notch. Sternite 4 having anterolateral margin slightly shorter than posterolateral margin, slightly concave, anteriorly angular, not produced to spine. Sternite 5 with anterolateral margin convex anteriorly, 0.6 × as long as posterolateral margin of sternite 4.

Abdomen: Smooth and nearly glabrous; somite 1 gently convex from anterior to posterior. Sternite 2 tergite 2.5 × broader than long; pleural lateral margins feebly concave, weakly divergent posteriorly; pleuron of somite 3 laterally blunt. Telson slightly less than half as long as broad, slightly concave on posterior margin, posterior plate 1.4 × longer than anterior plate.

Eye: Relatively long (1.7 × longer than broad), medially somewhat swollen, cornea not dilated, more than half length of remaining eyestalk.

Antennule and antenna: Ultimate article of antennular peduncle 3.5 × longer than high. Antennal article 2 with distinct lateral spine; antennal scale twice as broad as article 5 and slightly overreaching that article; article 4 with distinct distomesial spine; article 5 with small distomesial spine, length 1.7 × that of article 4, breadth 0.6 × height of ultimate article of antennule; flagellum of 12 or 13 segments far falling short of distal end of P1 merus.

Mxp: Mxp1 with bases close to each other. Mxp3 basis without denticle on mesial ridge. Ischium with distally rounded flexor margin, crista dentata with obsolescent denticles. Merus 1.8 × longer than ischium, flattish on mesial face, weakly ridged along flexor margin, distolateral spine small, flexor margin with 2 small, blunt spines distal to point two-thirds of length. Carpus with small distolateral spine.

Pereopods sparsely with soft fine setae.

P1: Slender, 5.2 × longer than carapace. Ischium dorsally with basally broad, dorso-ventrally depressed sharp spine, ventromesially with strong subterminal spine; merus 1.2 × longer than carapace, ventrally with 2 rows of spines: 1 row along mesial margin, consisting of 3 or 4 small spines, another row in line with subterminal spine of ischium, consisting of 5 large spines, distalmost largest. Carpus 1.2 × longer than merus. Palm 3.3 × longer than broad, 0.9 × length of carpus. Fingers slightly incurved distally, not gaping; movable finger half length of palm, opposable margin slightly concave, with proximal eminence; opposable margin of fixed finger convex, without prominence.

P2-4: Meri flattish on mesial face, moderately inflated on lateral face, dorsal margin rounded; subequal in length on P2 and P3, P4 merus 0.8 × length of P3 merus; successively narrower posteriorly; length-breadth ratio, 4.0 on P2 and P4, 3.4 on P4; P2 merus 0.9 × length of carapace,1.1 × longer than P2 propodus; P3 merus very slightly longer than P3 propodus; P4 merus 0.8 × length of P4 propodus. Carpi subequal, 0.4 × length of propodi on P2-4. Propodi successively longer posteriorly; flexor margin straight, ending in pair of long movable spines preceded by 4 single spines on distal twofifths length on P2-4. Dactyli slightly longer on P3 and P4 than on P2, much longer than carpi (1.4 ×, 1.6 ×, 1.6 × longer on P2, P3, P4, respectively), distinctly more than half (0.5 on P2, 0.6 on P2 and P4) as long as propodi, well compressed mesio-laterally, proportionately broad; flexor margin nearly straight, with 16, 18, 18 spines on P2, P3, P4 respectively, all obliquely directed and very close but not contiguous to one another, ultimate slender, penultimate 2 × broader than ultimate, remaining spines as broad as ultimate; antepenultimate spine 3.9-4.8 × longer than broad.

REMARKS — Uroptychus kareenae n. sp. is very close to U. adiastaltus n. sp. (see above), U. depressus n. sp. (see above) and U. levicrustus Baba, 1988 in the shape of sternite 4 and in the spination of pereopods. Uroptychus adiastaltus differs from the these three related species in the spination of the branchial lateral margin (see above under U. adiastaltus ), in having the sternite 3 anterior margin with a V-shaped emargination lacking a median notch, and in having the antennal article 4 unarmed. Uroptychus kareenae is differentiated from U. adiastaltus , U. depressus and U. levicrustus by the antennal article 5 that bears a distinct distomesial spine instead of being unarmed, and by the antepenultimate spines of the P2-4 dactyli that are long relative to breadth, with the length-breadth ratio, 3.9-4.8 instead of 2.0-2.9 (2.0- 2.7 in U. adiastaltus , 2.7-2.9 in U. depressus , 2.5-2.6 in U. levicrustus ). Moreover, the ultimate spines of the P2-4 dactyli are as broad as the antepenultimate spines in U. kareenae and U. levicrustus , while more slender in U. adiastaltus and U. depressus .

Uroptychus kareenae is distinguished from U. depressus by the following differences: the anterolateral spine of the carapace is closer to lateral orbital spine (these spines are separated by less than basal width of the anterolateral spine in U. kareenae , more than that in U. depressus ; the eyes are more elongate in U. kareenae (breadth-length ratio = 1.7 in U. kareenae , 1.4 in U. depressus ), reaching the distal third point of rostrum length instead of barely reaching the midlength of the rostrum; the antennal scale slightly overreaches article 5 in U. kareenae , reaching the first or second segment of the flagellum in U. depressus ; the gastric region in profile is smoothly sloping down anteriorly on to the rostrum in U. kareenae , preceded by the depressed rostrum in U. depressus .

Figures

FIGURE 111 Uroptychus kareenae n. sp., holotype, male 4.1 mm (MNHN-IU-2012-692). A, carapace and anterior part of abdomen, dorsal. B, same, lateral. C, sternal plastron,with excavated sternum,basal parts of Mxp1 included.D, telson.E, left antenna,ventral.F, left Mxp3,ventral.G, same,lateral. Scales bars: 1 mm.

FIGURE 112 Uroptychus kareenae n.sp.,holotype,male 4.1 mm (MNHN-IU-2012-692).A, right P1,proximal part,dorsomesial.B, same,ventral.C, same,dorsal. D, same, distal 3 articles, dorsal. E, same, fingers, ventral.F, left P2, lateral. G, same, distal part, setae omitted, lateral.H, left P3, setae omitted, lateral.I, same,distal part,lateral.J, left P4, setae omitted,lateral.K, same,distal part,lateral.Scales bars: 1 mm.