Uroptychus hesperius, Ahyong & Poore, 2004

Ahyong, Shane T. & Poore, Gary C. B., 2004, The Chirostylidae of southern Australia (Crustacea: Decapoda: Anomura), Zootaxa 436 (1), pp. 1-88 : 44-46

Uroptychus hesperius n. sp. ( Fig. 11 )

Type material. HOLOTYPE: SAM C6083 , female (11.5 mm), 231 km E of Cape Arid , Western Australia, 34°03’S, 125°31’E, 1011–1020 m, trawled, stn 15, K. Gowlett­Holmes et al., 31 Jul 1988.

Diagnosis. Carapace excluding rostrum broader than long; lateral margins serrated, convex, divergent, broadest posterior to midlength; with strong anteriorly directed anterolateral spine; outer orbital angle rounded; dorsum finely setose; sparsely granulate proximally. Rostrum triangular, about two­thirds remaining carapace length. Sternite 3 depressed, anterior margin deeply concave with short, U­shaped median notch. Ultimate and penultimate segments of antennal peduncle with distal spine. Antennal scale extending to apex of ultimate segment of peduncle. Cheliped propodal palm about about 3 times as long as pollex. Pereopods 2–4 merus with spinous extensor and flexor margins; propodus distinctly broadened distally, bearing 7–9 movable spines on distal flexor margin, distalmost paired; dactylus with 8 or 9 slender, corneous, obliquely directed spines on flexor margin.

Description. Carapace: Breadth greater than length (excluding rostrum). Lateral margins serrated, convex, divergent, broadest posterior to midlength; with strong anteriorly directed anterolateral spine. Rostrum triangular, about two­thirds remaining carapace length; lateral margins with 2 spinules. Outer orbital angle rounded. Dorsum finely setose; sparsely granulate proximally; lateral margins sparsely setose. Pterygostomian flap with strong anterior spine and small spinules on upper proximal surface.

Sternum: Plastron broader than long, slightly widening posteriorly. Sternite 3 (at base of maxilliped 3) depressed, anterior margin deeply concave with short, U­shaped median notch, anterolateral angle acute, outer margin irregular and tuberculate. Sternite 4 (at base of pereopod 1) with anterolateral margins acute and serrated, not produced anteriorly beyond outer base of sternite 3.

Abdomen: Segments finely setose. Telson about half as long as broad; distal portion posteriorly emarginate, about 1.5 times length of proximal portion.

Eye: Cornea not dilated, about one­third length of peduncle; not extending beyond proximal third of rostrum.

Antenna: Ultimate segment of peduncle about twice as long as penultimate segment, both with distal spine. Antennal scale about as wide as penultimate peduncular segment, extending to apex of ultimate segment of peduncle.

Maxilliped 3: Dactylus and propodus unarmed. Carpus with small distal and 2 small proximal spines on extensor margin. Merus with 2 distal spines and 3 or 4 spines on distal flexor margin. Ischium with crista dentata finely and evenly denticulate along entire length of ischium, not extending onto basis.

Pereopod 1 (cheliped): Slender, cylindrical, more than 2.5 times carapace length; all segments rugose and sparsely setose. Propodus with palm about 6 times as long as high, about 3 times as long as pollex. Fingers crossing, occlusal margins dentate and each with low process proximally. Carpus longer than merus, as long as palm, upper distal margin spinose. Merus distal and inner margin spinous; dorsal margin lacking spines. Ischium with serrated inner and spinous outer distal margin.

Pereopods 2–4: Sparsely setose, similar, decreasing in length posteriorly. Meri with spinous extensor and flexor margins. Carpi about 0.6 merus length and 0.6 propodus length. Propodi distinctly broadened distally, bearing 7–9 movable spines on distal flexor margin, distalmost paired. Dactyli with 8 or 9 fixed, slender, corneous, obliquely directed spines on flexor margin.

Ovum : 1.5 mm diameter.

Etymology. From the Latin, hesperius , meaning ‘western’, alluding to the Western Australian type locality.

Remarks. Uroptychus hesperius n. sp. closely resembles U. xipholepis Van Dam, 1933 from Indonesia, U. hamatus Zarenkov & Khodina, 1981 from the Marcus­Necker Rise, and U. subsolanus n. sp. in carapace shape, the serrated or spinous carapace margins and in the distally broadened propodus margins on the first three walking legs. Uroptychus hesperius differs from each of the aforementioned species in having a rounded instead of spinous outer orbital margin, in bearing fine setae on the dorsum of the carapace and abdomen, in having spines on the extensor margin of the merus of the walking legs and in having the fingers of the chelae almost one third instead of about one half the palm length. Uroptychus hesperius also resembles U. edisonicus Baba & Williams, 1998 from the Bismark Archipelago, in carapace shape and in the broadened propodi of the walking legs. Uroptychus edisonicus differs from U. hesperius in having spinular instead of rounded outer orbital angles, smooth instead of serrated carapace margins, and in lacking terminal spines on the distal two segments of the antennal peduncle.

Distribution. Known only from the type locality: 231 km east of Cape Arid, Western Australia at 1011–1020 m depth.

Figures

FIGURE 11. Uroptychus hesperius n. sp., holotype female, 11.5 mm, SAM C6083. A, dorsum. B, anterior carapace, right lateral. C, cheliped merus, proximal right lateral. D, telson. E, sternum. F, maxilliped 3, right lateral. G, crista dentata, right. H, antenna, right ventral. Scale A–C = 3 mm, D– F = 1.5 mm, G–H = 0.8 mm.