Uroptychus beryx, 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 : 103-107

Uroptychus beryx n. sp.

Figures 36 , 37

TYPE MATERIAL — Holotype: New Caledonia, Norfolk Ridge. BERYX 11 Stn CH 49, 23°45’S, 168°17’E, 400-460 m, 21.X.1992, ov. ♀ 2.5 mm ( MNHN-IU-2013-8514 ).

ETYMOLOGY„ Named for the BERYX 11 cruise by which the new species was collected; used as a noun in apposition.

DISTRIBUTION„ Norfolk Ridge; 400- 460 m.

DESCRIPTION„ Small species. Carapace: Slightly longer than broad (length 1.06 × breadth); greatest breadth 1.7 × distance between anterolateral spines. Dorsal surface feebly convex from anterior to posterior, without distinct groove, with sparse short setae, unarmed except or a few spinules on hepatic region. Lateral margins slightly divergent posteriorly, with row of about 10 small lateral spines along entire length; anterolateral spine slightly falling short of tip of lateral orbi- tal spine; spine at anterior end of branchial region well developed, preceded by 1 or 2 small spines, with accompanying smaller spine dorsomesial to it, followed by 7 spines (first of these much smaller and ventral to level of remainder, last closer to posterior end than to preceding). Rostrum slightly deflected ventrally, deeply excavated dorsally, with 2 subapical spines (proximal obsolescent) on lateral margin; length about half that of carapace, breadth somewhat more than half carapace breadth measured at posterior carapace margin. Lateral orbital spine well developed, slightly smaller than anterolateral spine, both situated at same level and close to each other, but not contiguous in dorsal view.

Sternum: Excavated sternum with anterior margin transverse between bases of Mxp1, surface feebly ridged in midline. Sternal plastron slightly broader than long, somewhat broader posteriorly. Sternite 3 shallowly depressed; anterior margin well emarginate, with U-shaped median notch flanked by small but distinct spine, laterally sharp angular. Sternite 4 with slightly convex anterolateral margin anteriorly angular or with small spine, posterolateral margin slightly shorter than anterolateral margin. Anterolateral margin of sternite 5 anteriorly convex, about as long as posterolateral margin of sternite 4.

Abdomen: Smooth, with sparse tufts of setae. Somite 1 feebly convex from anterior to posterior. Somite 2 tergite 2.3 × broader than long; pleural lateral margins concavely divergent posteriorly, posterolateral end somewhat angular. Pleura of somites 3 and 4 laterally angular. Telson slightly less than half as long as broad; posterior plate somewhat emarginate on posterior margin, length two-thirds length of anterior plate.

Eye: Relatively broad (1.6 × longer than broad), with subparallel lateral and mesial margins, overreaching midlength of rostrum, falling short of rostral tip. Cornea not dilated, half as long as remaining eyestalk.

Antennule and antenna: Ultimate article of antennular peduncle 2.8 × longer than high. Antennal peduncle ending in distal margin of cornea. Article 2 with strong distolateral spine. Antennal scale tapering, barely reaching distal end of article 5, breadth 1.3 × that of article 4. Article 4 with distinct distomesial spine. Article 5 unarmed, 1.5 × longer than article 5, breadth three-quarters height of ultimate antennular article. Flagellum consisting of 12 (left) or 9 (right) segments, reaching distal end of P1 merus.

Mxp: Mxp1 with bases broadly separated. Mxp3 basis without denticles on mesial ridge. Ischium flexor margin rounded distally, crista dentata with 30 small denticles diminishing toward distal end. Merus 2 × longer than ischium, moderately ridged along flexor margin bearing small spine at distal third; distolateral spine distinct. Carpus also with distolateral spine.

P1-4 with long soft setae. P1: 4.0 × longer than carapace. Ischium dorsally with basally broad, depressed, short spine, ventrally with 2 denticles proximally, without subterminal spine. Merus about as long as carapace, bearing spines (1 dorsal row in midline, 1 dorsomesial row, a few mesial spines, another few small spines on proximo-ventral surface close to mesial margin, and ventral distomesial and distolateral spines). Carpus slightly longer than merus, dorsally with 4 tubercle-like processes directly distal to juncture with merus. Palm with subparallel lateral and mesial margins, 3.0 × longer than broad, 1.2 × longer than carpus. Fingers ending in slightly incurved blunt spine; movable finger half as long as palm, opposable margin with median process; opposing margin of fixed finger nearly straight.

P2-4: Relatively broad and thick, sparse setose. Meri subequal in length on P2 and P3, P4 merus 0.9 × as long as and 0.9 × as broad as P3 merus; length-breadth ratio, 2.8-3.2 on P2, 2.8-2.9 on P3, 2.8 on P4; P2 merus 0.7 × as long as carapace and subequal to length of P2 propodus; P3 merus 0.8 × length of P3 propodus; P4 merus 0.7 × length of P4 propodus; dorsal crest with 7 (left) or 5 (right) spines on P2, 6 on P3, 2 or 3 on P4, one of these situated at distal end; ventrolateral margin with small but distinct terminal spine. Carpi slightly shorter posteriorly (P3 carpus 0.96 × length of P2 carpus, P4 carpus 0.95 × length of P3 carpus), much shorter than dactyli; carpus-propodus length ratio, 0.37 on P2, 0.36 on P3, 0.34 on P4; extensor margin with 1 proximal and 1 distal spine. Propodi subequal; flexor margin ending in pair of spines preceded by 4 or 5 spines on P2, 3 or 4 on P3, 3 on P4. Dactyli relatively stout, ending in slender spine preceded by 9 or 10 sharp strong spines nearly perpendicular to slightly curving flexor margin and gradually smaller proximally (proximal spines somewhat oblique); dactylus-carpus length ratio, 1.4 on P2, 1.6 on P3, 1.7 on P4, dactylus-propodus length ratio, 0.6 on P2-4.

Eggs. Number of eggs carried, 7; size, 0.90 mm × 1.02 mm.

REMARKS — The new species resembles U. multispinosus Ahyong & Poore, 2004 and U. vicinus n. sp., in having the anterolateral spine slightly larger than or subequal to the lateral orbital spine and in having the anterior margin of sternite 3 with median notch. Uroptychus beryx differs from U. multispinosus in the following features: the rostrum is as long as instead of longer than broad; the antennal scale is slightly broader instead of more than twice broader than article 5, falling short of instead of extending far beyond the apex of article; the antennal article 5 is unarmed instead of bearing a distinct distal spine; the P2-4 meri bear spines instead of being unarmed on the dorsal crest; and the P2-4 dactyli bear more numerous and more closely arranged flexor spines (9 or 10 instead of 6 or 7 spines that are more loosely arranged). The relationships with U. vicinus are discussed under that species (see below).

Figures

FIGURE 36 Uroptychus beryx n. sp., holotype,ovigerous female 2.5 mm (MNHN-IU-2013-8514). A, carapace and anterior part of abdomen, proximal part of right P1 included,dorsal. B, same,lateral. C, sternal plastron,with excavated sternum and basal parts of Mxp1. D, telson. E, left antenna, ventral. F, left Mxp3, setae omitted, ventral.G, same,lateral.H, right P1, proximal part, setae omitted, ventral.I, same, distal part, dorsal. Scale bars: 1 mm.

FIGURE 37 Uroptychus beryx n. sp., holotype, ovigerous female 2.5 mm (MNHN-IU-2013-8514). A, left P2, lateral. B, same, distal part, setae omitted,lateral. C, left P3, setae omitted,lateral. D, right P4, lateral. Scale bars: 1 mm.