Coleusia urania (Herbst, 1801)

(Figs. 1, 2, 4–6)

Cancer urania Herbst, 1801: 17, pl. 53, fig. 3.

Leucosia urania — Lichtenstein 1816: 140.— Leach 1817: 21.— Desmarest 1825: 167.— White 1847: 48 (part).— Gibbes 1850: 185.— Bell 1855a: 362.— Bell 1855b: 283.— Bell 1855c: 5.— Serène 1968: 47. Leucosia anatum – K. Sakai 1999: 19, pl. 7F (not Cancer anatum Herbst, 1783).

Leucosia grandis – Chen & Sun 2002: 422, fig. 190, pl. 16.5, 6 [name not available, see above].

Coleusia urania — Galil 2006: 64, figs. 2E, F, 3E, 4D.—Ng et al. 2008: 94.

Not Leucosia urania — Bianconi 1867: 341.— Hilgendorf 1869: 110.—De Man 1881: 256 [= Coleusia signata (Paul’son, 1875)]

Not Leucosides urania — Rathbun 1910: 309, pl. 1, fig. 1.— Suvatti 1950: 143. [= Soceulia brunnea Miers, 1877].

Not Leucosia urania — Hilgendorf 1879: 811 [= Coleusia rangita Galil, 2006].

Not Leucosia urania — Naiyanetr 1998: 58.— Naiyanetr 2007: 69 [= Soceulia brunnea Miers, 1877].

Not Leucosia urania — Alcock 1896: 220 [= Coleusia new species, Promdam et al., 2014].

Material examined. China. Guangdong Province, Haimen, 07– 15.05.1957, coll. Z. Fan, paratype of Leucosia grandis Chen & Türkay, 1 ♂ (42.6 × 38.7 mm) (SMF 25700); Guangdong Province, Shan Wei, 22°46.60’N 115°20.60’E, donated H.L. Chen, IOCAS, 1 ♂ (38.7 × 34.8 mm) (ZRC 2013.1295). Taiwan. Su-Ao, Nangfangao, 0 5.11.2000, coll. P.K.L. Ng, 2 ♂ (40.9 × 36.8 mm, 40.3 × 36.5 mm) (ZRC 2001.0045); Su-Ao, Nangfangao, 23.03.1999, coll. M.-S. Hung, 1 ♂ (35.7 × 40.1 mm) (ZRC 2014.0175); Tahsi, 0 6.04.1986, coll. J.-F. Huang, 1 ♂ (35.8 × 39.4 mm) (ZRC 2014.0174).

Description. Carapace (Figs. 1, 2 B, 4A) subpentagonal, globose, 1.1 times as long as wide; dorsal surface glabrous, smooth, sparsely punctate; regions indistinct. Frontal region produced, upcurved, deeply concave medially, laterally constricted; frontal margin rounded. Anterolateral margin sinuous, with obsolescent granules distally (Figs. 2 B, 4A). Lateral angle of carapace rounded, overhanging thoracic sinus, margin prominently beaded, granules lozenge-shaped. Posterolateral margins rounded, smooth (Figs. 2 B, 4A). Epimeral margin invisible in dorsal view, gutter-like anteriorly, narrowing posteriorly, closely beaded marginal granules decreasing in size posteriorly, meeting posterior margin at an angle. Posterior margin minutely granular, sinuous in male (Fig. 4 A), slightly rounded in female (Fig. 2 B); deflexed posterior surface smooth.

Antennule obliquely folded into fossa, fossa sealed by basal antennular segment. Antennae short, inserted between antennular fossa, orbit. Orbits small, rounded, outer orbital margin with single suture, anterior margin of efferent branchial channel forms part of lower orbital margin. Eyes retractable. External maxillipeds completely concealing trapezoid buccal opening, smooth; endopod merus triangular, as long as ischium; in female, endopod with setose fringe lengthwise, ischium medially elevated, keel-like (Fig. 4 F).

Thoracic sinus deep, tomentose, anterior margin level with base of coxopodite of third maxillipeds, anteriorly defined by overhanging beaded margin of pterygostomian region; ventral margin medially with row of oval granules, decreasing in size posteriorly (Figs. 2 E, 4B). Thoracic sternites smooth, shiny; sternites 1–3 completely fused, trapezoidal, separated from sternite 4 by sinuous suture; sternites 4–8 with medially interrupted sutures between them (Fig. 4 F); distinct peg-like abdominal locking mechanism on sternite 5, adjacent to sternite 4 in male. Abdominal cavity nearly reaching buccal cavity, lateral margins prominently ridged medially, ridge fitting into notch between somites 5, 6 (Fig. 4 F). Male abdomen smooth; somite 1 narrow, transverse; somite 2 small, narrow, spindle-shaped; somites 3–6 fused, proximally inflated, furrowed lengthwise, suture between somites 5, 6 distinct but somites immovable; somite 6 elongated, lateral margins evenly curved, narrowing distally, with prominent triangular denticle subproximally; telson triangular, lateral margins gently convex, as wide as long (Fig. 4 F). Female abdomen with somites 3–6 fused, greatly enlarged, shield-like, telson triangular (Fig. 2 C).

G1 elongated, shaft stout, sinuous, tightly coiled 3 times on its axis, ultimate coil swollen, setose; apical process cornute, beak-like, curved interiorly (Figs. 5, 6). G2 relatively short, slender, apex scoop-like (Fig. 6 D, E).

Chelipeds subequal, robust, relatively longer in adult male (Fig. 4 A) than in females (Fig. 2 B). Merus trigonal; anterior, posterior margins lined along their length with perliform granules, diminishing in size distally; upper surface with coalesced cluster of granules proximally, followed by 4 large perliform granules, distally smooth; lower surface pitted, proximally granular, laterally with rows of small granules (Figs. 2 F, 4C). Carpus inflated, smooth (Figs. 2 B, 4A). Propodus lenticular, slightly longer than wide, upper margin rounded, smooth; lower margin with row of granules, lower external surface with small, rounded granules (Figs. 2 B, 4A, D). Fingers as long as propodus, gaping, cutting edges, finely teethed (Fig. 4 A).

Ambulatory legs similar in shape, gradually decreasing in length from first to fourth (Figs. 1, 2 B, 4A). Coxal condyles rounded. Meri subcylindrical; first 3 meri with anterior parts bearing 2 granular rows on respective dorsal margin, posterior parts distally obsolescent, 2 granular rows on ventral margins, anterior parts proximally obsolescent; merus of last leg with single granular row dorsally, prominently granular crest subproximally on ventral margin (Fig. 4 E). Carpi rounded, minute denticle on upper surface (Fig. 4 E). Propodi dorsally, ventrally carinate, expanded, foliaceous (Fig. 4 A, E). Dactyli longer than propodi, lanceolate, subspatuliform (Fig. 4 E).

Colour. Dorsal surface of carapace yellowish orange to white, paler laterally and posteriorly; a broad whitish stripe proceeding backwards from the front; two large spots on the posterior part of the carapace, and two smaller ones on each lateral margin, the basal portion of the fingers, and a ring on each segment of the ambulatory legs, are all rust coloured (Fig. 1). Ventral surface paler grey.

Remarks. Coleusia urania (Herbst, 1801) differs from its congeners— C. biannulata (Tyndale-Biscoe & George, 1962), C. magna (Tyndale-Biscoe & George, 1962), C. rangita Galil, 2006, C. signata (Paulson, 1875) — in having a prominently granular rather than smooth fourth ambulatory merus (Fig. 4 E); an expanded, distinctly foliaceous ambulatory propodus (Figs. 2 B, C, 4A, E); the interiorly curved beak-like apical process of the G1 (Figs. 5, 6 A–C); and in its distinctive color pattern (Fig. 1). The record of “ Leucosia urania ” from the Andaman Sea by Alcock (1896: 220) must be referred to a new species of Coleusia (Promdam et al. 2014) . The same is true for some specimens identified as " Leucosia grandis " by Chen & Sun (2002: 422) from the Gulf of Thailand and Singapore. This new species is superficially similar to C. urania but differs in the form of the chelipeds and most significantly, in a different G1 structure. The records from the Gulf of Thailand by Rathbun (1910: 309, as Leucosides urania) and Naiyanetr (1998: 58; 2007: 69, as Leucosia urania) are misidentifications of Soceulia brunnea (Miers, 1877) (Galil 2006: 64) .

Distribution. China and Taiwan.