Uroptychus longicheles, 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 : 55-58

Uroptychus longicheles n. sp. ( Fig. 15 )

Type material. HOLOTYPE: AM P65826, ovigerous female (3.0 mm), Gifford Guyot, Tasman Sea , 26°44.27’S, 159°28.93’E, 306 m, on Subergorgia coral, beam trawl, FR0589­39, J. Lowry et al. on RV Franklin, 8 May 1989.

Diagnosis. Carapace excluding rostrum broader than long; broadest at about midlength; lateral margins convex, with anterolateral spine and 4 or 5 lateral spines; dorsum unarmed. Rostrum elongate, about half as long as remaining carapace, apex rounded, margins concave, dorsally with shallow concavity. Outer orbital angle produced to distinct spine. Sternite 3 slightly depressed, anterior margin shallowly concave, with narrow Vshaped median notch. Basal antennal segment with distinct outer spine; ultimate segment unarmed; penultimate with distal spine. Antennal scale extending to midlength of ultimate peduncle segment. Cheliped about 4.5 times carapace length. Pereopods 2–4 similar; propodi not broadened distally, with movable spine on distal flexor margin; dactyli with 7 or 8 widely spaced, obliquely directed, corneous teeth on flexor margin, penulimate distinctly larger and broader than others.

Description. Carapace: breadth greater than length (excluding rostrum); broadest at about midlength. Lateral margins convex, with slender anteriorly directed anterolateral spine and 4 or 5 lateral spines, first and fourth largest. Rostrum elongate, about half as long as remaining carapace, apex rounded, margins concave, dorsally with shallow concavity. Outer orbital angle produced to distinct spine, extending anteriorly beyond apices of anterolateral spines. Dorsum sparsely setose, unarmed. Pterygostomian flap with strong anterior spine and scattered spinules over lateral surface.

Sternum: Plastron as long as broad, subquadrate. Sternite 3 (at base of maxilliped 3) slightly depressed, anterior margin shallowly concave, with narrow V­shaped median notch, anterolateral angle obtuse, flanked laterally by low tooth. Sternite 4 (at base of pereopod 1) with lateral margins produced, angular, extending anteriorly to outer base of sternite 3.

Abdomen: Segments sparsely setose. Telson slightly almost twice as wide as long; distal portion faintly emarginate, less than twice length of proximal portion.

Eye: Cornea not dilated, about half­length of peduncle; extending to distal quarter of rostrum.

Antenna: Basal segment with distinct outer spine. Peduncle extending to distal quarter of rostrum. Flagellum almost 2 times as long as peduncle. Ultimate segment about as long as penultimate segment; penultimate with distal spine. Antennal scale wider than opposite peduncular segments, extending to midlength of ultimate peduncle segment

Maxilliped 3: Dactylus, propodus and carpus unarmed. Merus with distal extensor spine and smaller spine distal to midlength of flexor margin. Crista dentata denticulate for proximal four­fifths of ischium, not extending onto basis.

Pereopod 1 (cheliped): Slender, subcylindrical, with setose scales, about 4.5 times carapace length. Propodus palm 5 times as long as high, about 3 times as long as pollex. Fingers crossing, occlusal margins dentate, irregular. Carpus longer than merus, slightly shorter than propodal palm. Ischium with slender distolateral spine.

Pereopods 2–4: Setose, similar, slightly decreasing in length posteriorly. Propodi not broadened distally, with pair of movable spines on distal flexor margin. Dactyli with 7 or 8 widely spaced, obliquely directed, corneous teeth on flexor margin, penulimate distinctly larger and broader than others. Pereopods 2–3 carpus about 0.4 merus and propodus length. Pereopod 4 carpus about 0.4 merus length, 0.3 propodus length.

Etymology. The specific epithet alludes to the greatly elongate chelipeds of the species in comparison to the similar species U. amabilis Baba, 1979 .

Remarks. Uroptychus longicheles n. sp. closely resembles U. amabilis Baba, 1979 , from New Caledonia, in carapace shape with narrow, excavated rostrum, deeply concave orbits, the long ocular peduncles and the similar shape of the sternum. The new species is readily distinguished from U. amabilis in the following features: carapace margins are spinose, the distal segment of the antennal peduncle is unarmed, the antennal scale reaches almost to the midlength instead of near the apex of the distal peduncle segment, the chelipeds are about five instead of three times carapace length, and the spines on the flexor margin of the dactyli of the walking legs are more slender and oriented obliquely instead of perpendicular to the dactylar margins.

The single known specimen of U. longicheles is an ovigerous female collected from the coral Subergorgia . It was carrying three advanced embryos of large size: 1.0 x 0.85 mm vs. 3.0 mm carapace length of the holotype. The advanced stage of the embryos suggests that the species might undergo direct development limiting dispersal ability.

Distribution. Presently known only from the type locality.

Figures

FIGURE 15. Uroptychus longicheles n. sp., holotype female, 3.0 mm, AM P65826. A, dorsum. B, anterior carapace, right lateral. C, cheliped merus, left ventral. D, cheliped merus, right lateral. E, telson. F, sternum. G, maxilliped 3, right lateral. H, crista dentata, right. I, antenna, right ventral. A– D = 1 mm, E–G = 0.5 mm, H–I = 0.3 mm.