Uroptychus lanatus, 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 : 256-259

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Uroptychus lanatus

n. sp.

Uroptychus lanatus n. sp.

Figures 117 View FIGURE 117 , 118 View FIGURE 118

TYPE MATERIAL — Holotype: Indonesia, Kai Islands. KARUBAR Stn CP17, 5°15’S, 133°01’E, 459- 439 m, with coral, possibly belonging to Chrysogorgiidae ( Calcaxonia) , 24.X.1991, ov. ♀ 2.8 mm ( MNHN-IU-2011-5958 ) GoogleMaps . Paratypes: Collected with holotype, same host, 3 ♂ 2.4-3.0 mm, 2 ov. ♀ 2.7, 3.0 mm (MNHN-IU-2011-5960, MNHN-IU-2011-5961, MNHN-IU-2014-16611) . Vanuatu. MUSORSTOM 8 Stn CP975, 19°23.60’S, 169°28.93’E, 566- 536 m, 22.IX.1994, 1 ♀ 3.8 mm (MNHN-IU-2011-5959).

ETYMOLOGY„ From the Latin lanatus (soft), alluding to soft setae covering the body, characteristic of the species.

DISTRIBUTION„ Kai Islands and Vanuatu; 459- 536 m.

SIZE„ Males, 2.4-3.0 mm; females 2.7-3.8 mm; ovigerous females from 2.7 mm.

DESCRIPTION„ Small species. Body densely covered with soft fine setae. Carapace: 1.1-1.2 × broader than long; greatest breadth 1.7 × distance between anterolateral spines. Dorsal surface somewhat convex from anterior to posterior, without distinct groove. Lateral margins convexly divergent posteriorly, bearing several small spines; first anterolateral, largest, slightly overreaching lateral orbital spine; second rather remote from first, usually equidistant between first and third, rarely with accompanying small spine mesial to it; remaining spines situated on anterior half of posterior branchial region. Rostrum sharply triangular, with interior angle of 25-27°, deflected ventrally; length about half or slightly less than half that of remaining carapace, breadth distinctly less than half carapace breadth at posterior carapace margin; dorsal surface concave. Lateral orbital spine smaller than, moderately remote from, and slightly anterior to level of anterolateral spine. Pterygostomian flap anteriorly angular, produced to small spine, surface unarmed.

Sternum: Excavated sternum anteriorly triangular, surface with weak ridge in midline. Sternal plastron much broader than long, lateral extremities convexly divergent posteriorly. Sternite 3 weakly depressed; anterior margin nearly semicircular or of very broad V-shape, without median notch and submedian spines, laterally sharply produced or bluntly angular. Sternite 4 having anterolateral margin convex, anteriorly rounded, bearing a few distinct or obsolescent denticles, posterolateral margin short, less than half as long as anterolateral margin. Anterolateral margin of sternite 5 strongly convex, much longer than (2 x) posterolateral margin of sternite 4.

Abdomen: Somite 1 slightly convex from anterior to posterior, without transverse ridge. Somite 2 tergite 2.4-2.9 × broader than long; pleuron posterolaterally blunt, lateral margin slightly concave, moderately divergent posteriorly. Pleuron of somite 3 with blunt lateral margin. Telson 0.4 × as long as broad; posterior plate nearly as long as or slightly shorter than anterior plate, posterior margin feebly or somewhat concave, not emarginate.

Eye: Relatively short (1.4-1.6 × longer than broad), terminating in midlength of rostrum, medially somewhat inflated, distally narrowed. Cornea not dilated, about half length of remaining eyestalk.

Antennule and antenna: Ultimate article of antennular peduncle 2.8-3.0 × longer than high. Antennal peduncle overreaching eyes by half length of article 5. Article 2 with small lateral spine. Antennal scale distinctly overreaching distal end of antennal peduncle, breadth 1.7 × that of article 5 or slightly more. Articles 4 and 5 each with distoventral spine very small or barely discernible. Article 5 1.3-1.5 × length of article 4, breadth 0.6-0.7 height of ultimate article of antennular peduncle. Flagellum of 10-11 segments reaching or somewhat overreaching distal end of P 1 merus.

Mxp: Mxp1 with bases close to each other but not contiguous. Mxp3 with plumose setae on lateral surface of merus and carpus, other than brushes. Basis without denticles on mesial ridge. Ischium with flexor margin not rounded distally; crista dentata with numerous small distally diminishing denticles. Merus 2.1 × as long as ischium, flattish on mesial face, with distinct distolateral spine and a few small or obsolescent spines anterior to midlength of flexor margin. Carpus with small or obsolescent distolateral spine.

Pereopods thickly covered with soft, fine, plumose setae. P 1: Massive, 4.7-4.8 × (males), 3.9-4.1 × (females) longer than carapace. Ischium dorsally with short spine, ventromesially with several small spines obscured by setae, subterminal spine very small. Merus 0.8-1.0 × length of carapace, usually with ventral distomesial spine, rarely with a few tubercular processes on proximal mesial margin. Carpus 1.1 × longer than merus. Palm 2.5-2.7 × (females), 2.5-3.0 × (males) longer than broad, 1.2-1.6 × longer than carpus. Fingers depressed, relatively broad, directed straight forward in females and small males, somewhat laterally directed in largest male, distally incurved, crossing when closed; movable finger having opposable margin with bluntly triangular median process fitting to groove between 2 low eminences on opposite face of fixed finger when closed, length usually 0.4 ×, rarely 0.5 × (non-ovigerous female) that of palm.

P 2-4: Somewhat compressed mesio-laterally. Meri and carpi unarmed. Meri successively shorter posteriorly ( P 3 merus 0.9 × length of P 2 merus, P 4 merus 0.8 × length of P 3 merus), subequally broad on P 2 and P 3, very slightly narrower on P 4 than on P 3; length-breadth ratio, 3.2-3.9 on P 2, 3.1-3.9 on P 3, 2.6-3.2 on P 4; dorsal margin unarmed; P 2 merus 0.7-0.8 length of carapace, 0.9 × length of P 2 propodus; P 3 merus 0.9 × length of P 3 propodus; P 4 merus 0.7-0.8 × length of P 4 propodus. Carpi subequal in length on P 2 and P 3 or slightly longer on P 2 than on P 3 and shortest on P 4; carpus-propodus length ratio, 0.5 on P 2, 0.4-0.5 on P 3, 0.4 on P 4; unarmed. Propodi subequal on P 2-4 or longer on P 3-4 than on P 2; flexor margin slightly convex (rarely somewhat more convex on P 2), ending in pair of spines preceded by 6-7 slender movable spines on distal two-thirds on P 2, 6 spines in distal half on P 3, 4-5 spines on P 4. Dactyli longer on P 3 and P 4 than on P 2; dactylus-carpus length ratio, 0.9-1.0 on P 2, 1.0-1.1 on P 3, 1.2 on P 4; dactylus-propodus length ratio, 0.4-0.5 on P 2-4; flexor margin moderately curving, ending in slender spine preceded by 7-9 subtriangular, moderately obliquely directed spines diminishing toward juncture with propodus, ultimate somewhat more slender than penultimate.

Eggs. Number of eggs carried, 10; size, 0.83 mm × 0.83 mm - 1.0 mm × 1.25 mm (smallest eggs yolky).

REMARKS — Uroptychus lanatus keys out together with U. perpendicularis n. sp., but it is closer to U. posticus n. sp. Their relationships are discussed under the remarks of that species (see below).