Uroptychus jiaolongae n. sp.

(Figs. 4, 7, 8 D)

Material examined. Holotype: Commensal with gorgonian coral, brink of cold seep community, ridge between continental shelf and slope, off Guangdong Province, China, southwest of Taiwan Island, northeastern South China Sea, MBM189176, 119 °17.116’E, 22°6.948’N, ovig. female (PCL 8.4 mm), 1138 m, coll. Jiaolong manned submersible of R/V Xiangyanghong 9, 19 June 2013.

Diagnosis. Carapace excluding rostrum distinctly longer than broad; lateral margins slightly divergent; with anterolateral spine and additional spine at base of anterior cervical groove; posterior half with low, uneven ridge; dorsal surface glabrous, armed with pair of strong epigastric spines. Rostrum sharply triangular. Sternite 3 strongly depressed, anterior margin shallowly emarginate, with narrow U-shaped notch and pair of median spines. Antennal with unarmed penultimate and ultimate article; antennal scale reaching proximal 0.2 of ultimate peduncle article. Pereopod 1 merus armed with 2 spines on dorsodistal margin, and 2 short spines on ventrodistal margin. Pereopods 2–4 propodi not broadened distally, with 5–9 movable corneous spines on distal half of flexor margin, none paired; dactyli flexor margin with 4–5 corneous spines on proximal third part; distal margin armed with 2 fixed, strong corneous spines.

Description. Carapace (Fig. 4 A) (excluding rostrum) distinctly longer than broad. Lateral margins slightly divergent, each armed with strong anterolateral spine, and additional spine at base of anterior cervical groove; posterior branchial margin (posterior half of lateral margin) uneven, with low, interrupted ridges. Rostrum sharply triangular, approximately one-third as long as remaining carapace, margins unarmed. Outer orbital angle obtuse. Dorsal surface of carapace glabrous, armed with pair of strong epigastric spines. Pterygostomian flap (Fig. 4 B) unarmed, anterior angle blunt.

Sternal plastron (Fig. 4 C) slightly broader than long, widening posteriorly. Sternite 3 strongly depressed, anterior margin concave, weakly denticulate, with indistinct U-shaped notch and pair of median spines; Sternites 4–7 each with transverse or oblique ridge on ventral surface, bearing simple setae.

Abdominal tergites glabrous and unarmed; first segment with dorsal surface transversely ridged. Telson (Fig. 4 D) distinctly broader than long; distal portion about twice length of proximal portion, distal margin nearly straight.

Eyestalk nearly reaching to distal quarter of rostrum; cornea slightly dilated, subequal to length of ocular peduncle.

Basal article of antenna (Fig. 4 E) short. Article 2 with triangular distolateral angle. Penultimate and ultimate article unarmed; ultimate article nearly twice as long as penultimate article. Antennal scale subtriangular, 3.1 times as long as broad, reaching proximal 0.2 of ultimate peduncle article. Peduncle extending to distal fourth of rostrum. Flagellum more than twice as long as peduncle.

Third maxilliped (Fig. 4 F) slender; ischium with well-developed crista dentata (Fig. 4 G) on proximal twothirds extending to basis; dactylus, propodus, carpus and merus unarmed.

Pereopods 1 (P1, chelipeds) (Fig. 4 A) subequal, slender, cylindrical, 4.7 times as long as carapace (excluding rostrum); segments (excluding fingers) glabrous and bearing several fine setae. Basis armed with distinct distomesial tooth. Ischium short, with coniform (Fig. 4 H) spine on distolateral margin. Merus about as long as carapace, with 2 strong spines on dorsodistal margin, and 2 short spines (Fig. 4 I) on mesial and lateral ends of ventrodistal margin. Carpus 1.7 times as long as carapace, straight, unarmed. Propodus palm slender, about 9.4 times as long as broad, 1.9 times as long as carapace, and 3.1 times as long as dactylus. Fingers (dactylus and fixed finger) crossing distally, bearing thick setae on surfaces and margins; occlusal margins (Fig. 4 J) finely denticulate, with low tooth proximally on dactylus, and indistinct process at base of fixed finger.

Pereopods 2–4 (P2–4) (Fig. 4 K–N) slender, sparsely setose. Meri about 5.3–7.5 times as long as wide, decreasing in length from P2 to P4; flexor margins each armed with distal spine. Carpi with margins smooth, unarmed, each about 0.63 times of P2 merus length. Propodi not broadened distally, each about 0.72 times of P2 merus length; extensor margin smooth; flexor margin armed with 5–9 movable corneous spines on distal half (none paired), bearing fine setae on bases of spines. Dactyli (Fig. 4 N) bent on proximal third, setose marginally; flexor margin armed with 4–5 corneous spines on proximal third part; distal margin armed with 2 fixed, strong corneous spines.

Ovum with diameter 2.0 mm.

Coloration. Red to dark orange, eyes bright yellow.

Habitat. Commensal with gorgonian coral living on the edge of cold seeps.

Distribution. Northern South China Sea.

Etymology. The specific name is dedicated to the Jiaolong manned submersible that collected the material.

Remarks. The new species strongly resembles U. sternospinosus Tirmizi, 1964 and U. soyomaruae Baba, 1981 in having a pair of strong epigastric spines, and the cheliped merus armed with spine(s) on dorsodistal margin. Uroptychus jiaolongae n. sp. differs from U. sternospinosus in having a glabrous dorsal carapace surface excluding the pair of epigastric spines, the cheliped carpus unarmed, and the P2–4 propodus not broadened distally. In U. sternospinosus, the carapace is covered with large, well-separated setose granules on dorsal surface; the cheliped carpus is spinose on dorsodistal margin; and the P2–4 propodus is broadened distally (Tirmizi 1964). Uroptychus jiaolongae n. sp. differs from U. soyomaruae in having a glabrous dorsal carapace surface excluding the epigastric spines, the lateral margin of carapace armed with additional spine at base of the anterior cervical groove, and the flexor margin of P2–4 dactylus armed with 4–5 corneous spines on the proximal third part. In U. soyomaruae, the carapace is covered with minute papilla-like granules; the lateral margin of carapace is unarmed excluding the anterolateral spine; and the flexor margin of P2–4 dactylus evenly armed with 8 corneous spines.

Uroptychus jiaolongae n. sp. also resembles U. australis (Henderson, 1885) in having a glabrous dorsal carapace surface (excluding the pair of epigastric spines), and uneven posterior branchial margins. The new species differs from the latter mainly in the size of epigastric spines, the presence of the spines at base of anterior cervical grooves, and the armature of the cheliped merus. Whereas in U. australis, the epigastric spines are much smaller; the lateral margins of carapace are unarmed excluding the anterolateral spines; and the cheliped merus is also unarmed (Ahyong & Poore 2004).

There are some other Uroptychus species in the Indo-West Pacific, such as U. bicavus Baba & de Saint Laurent, 1992, U. gracilimanus (Henderson, 1885), U. sagamiae (Baba, 2005) and U. singularis Baba & Lin, 2008 are similar to the new species in having a pair of epigastric spines and unarmed posterior branchial margins. These species are distinctive in having the much smaller or obsolescent epigastric spines, and completely unarmed chelipeds.