Uroptychus subsolanus, 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 : 75-77

Uroptychus subsolanus n. sp. ( Fig. 23 )

Type material. HOLOTYPE: NMV J17067 , 1 ovigerous female (10.3 mm), 63 km S of Point Hicks, Bass Strait , Victoria, 38°22.66’S, 149°18.41’E, 1073 m, 3.5 m beam trawl, SLOPE 68 , G. Poore et al., 25 Oct 1988 . PARATYPES: SAM C6072 , 1 male (7.0 mm), 1 female (7.9 mm), 231 km S of Eucla , South Australia, 33°45’S, 129°17’E, 999–1110 m, trawled, stn 28, FV Adelaide Pearl, K. Gowlett­Holmes et al., 1 Aug 1998 .

Diagnosis. Carapace excluding rostrum broader than long; lateral margins serrated, convex, divergent, broadest posterior to midlength; with strong anteriorly directed anterolateral spine and distinct spine at base of cervical groove; outer orbital angle produced to a small spine not reaching beyond midlength of anterolateral spine; dorsum minutely punctate. Rostrum triangular, about two­thirds remaining carapace length; lateral margins with 3–5 spinules. Sternite 3 depressed, anterior margin deeply concave with short, U­shaped median notch, anterolateral angle acute, outer margin irregular and tuberculate. Ultimate and penultimate segment of antennal peduncle with distal spine. Antennal scale extending beyond apex of ultimate segment of peduncle. Cheliped propodus with straight distoventral margin. Pereopods 2–4 merus unarmed dorsally; spinose distally; propodus distinctly broadened distally, bearing 6–8 movable spines on distal flexor margin, distalmost paired; dactylus with 7 or 8 triangular, 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 and distinct spine at base of cervical groove. Rostrum triangular, about two­thirds remaining carapace length; lateral margins with 3–5 spinules. Outer orbital angle produced to a small spine not reaching beyond midlength of anterolateral spine. Dorsum minutely punctate, devoid of setae; lateral margins sparsely setose. Pterygostomian flap with small 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 minutely punctate. 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 distal 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 beyond apex of ultimate segment of peduncle.

Maxilliped 3: Dactylus and propodus unarmed. Carpus with small distal extensor spine. Merus with 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, about twice carapace length; all segments rugose and sparsely setose. Propodus with palm about 4 times as long as high, about 2 times as long as pollex. Fingers crossing, occlusal margins dentate and each with low process proximally. Carpus longer than merus, as long as propodal palm, upper distal margin spinose. Merus distal and inner margin spinous; dorsal margin lacking spines. Ischium with serrated inner and outer spinous distal margin.

Pereopods 2–4: Similar, decreasing in length posteriorly. Meri unarmed proximally; spinose distally. Carpi about 0.5 merus length and 0.6 propodus length. Propodi distinctly broadened distally, bearing 6–8 movable spines on distal flexor margin, distalmost paired. Dactyli with 7 or 8 fixed triangular, corneous, obliquely directed spines on flexor margin.

Ovum : 1.4 mm diameter.

Etymology. From the Latin, subsolanus , meaning ‘eastern’, alluding to the eastern distribution of the species relative to U. hesperius n. sp.

Remarks. Uroptychus subsolanus n. sp., as with U. hesperius n. sp., closely resembles U. xipholepis Van Dam, 1933 from Indonesia and U. hamatus Zarenkov & Khodina, 1981 from the Marcus­Necker Rise, in carapace shape, in having serrated or spinous carapace margins and in having distally broadened ventral propodus margins on the first three walking legs. Distinguishing characters of U. hesperius are discussed above. Uroptychus subsolanus differs from U. xipholepis chiefly in having a longer antennal scale. The apex of the antennal scale of U. subsolanus distinctly overreaches the apex of the distal antennal segment instead reaching slightly beyond the midlength of the distal antennal segment. Additionally, the distoventral margin of the propodus of the chelae in U. subsolanus is straight instead of concave as in U. xipholepis . Uroptychus subsolanus differs from U. hamatus in having the antennal scale distinctly overeaching instead of reaching the apex of the distal antennal segment, and in lacking the dorsal longitudinal row of spines on the carpus of the chelipeds.

Distribution. Known from Bass Strait and the vicinity of Eucla, South Australia at depths of 999–1110 m.

Figures

FIGURE 23. Uroptychus subsolanus n. sp., holotype female, 10.3 mm, NMV J17067. A, dorsum. B, anterior carapace, right lateral. C, cheliped, 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, H = 1.5 mm, G = 0.8 mm.