Uroptychus paracrassior, 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 : 66-68

Uroptychus paracrassior n. sp. ( Fig. 19 )

Type material. HOLOTYPE: AM P31408, ovigerous female (7.0 mm), NE of Tweed Heads , Queensland, 28°02–05’S, 153°57’E, 364 m, demersal trawl, K78­09­03, 1 Jun 1978 . PARATYPES: AM P31409, 1 male (4.9 mm), NE of Tweed Heads , Queensland, 28°02–06’S, 153°56’E, 368 m, trawl, from antipatharian, K78­17­06, 16 Aug 1978 ; AM P31410, 2 males (3.5–5.4 mm), NE of Tweed Heads , Queensland, 28°02–06’S, 153°56’E, 368 m, trawl, from antipatharian, K78­17­06, 16 Aug 1978 ; AM P31416, 5 males (4.0– 5.8 mm), 5 females (4.6–6.7 mm), NE of Tweed Heads , Queensland, 28°04’S, 153°56’E, 380 m, K78­17­06, from antipatharian, 16 Aug 1978 .

Diagnosis. Carapace excluding rostrum broader than long; broadest posterior to midlength; lateral margins divergent, with strong anterolateral spine and 6–10 lateral spines; outer orbital angle produced to distinct spine; dorsum unarmed. Rostrum sharply triangular, about half as long as remaining carapace, margins unarmed. Sternite 3 slightly depressed, anterior margin deeply concave, with V­shaped median notch and pair of median spines. Basal antennal segment with distinct outer spine; ultimate and penultimate segments with distal spine. Antennal scale extending to or beyond apex of ultimate peduncle segment. Maxilliped 3 carpus with distal extensor spine; merus with 2–4 distal flexor spines and 1 or 2 distal extensor spines. Pereopods 2–4 similar; propodi slightly broadened distally, with 6–9 movable spines on distal flexor margin, distalmost paired; dactyli with 9–11 strong, obliquely directed, corneous teeth on flexor margin.

Description. Carapace: Breadth greater than length (excluding rostrum); broadest posterior to midlength. Lateral margins divergent, with strong anteriorly directed anterolateral spine and 6–10 lateral spines. First and third lateral spine largest; first usually with small spine mesially. Rostrum sharply triangular, about half as long as remaining carapace, margins unarmed, dorsally with shallow concavity. Outer orbital angle produced to distinct spine, not extending anteriorly beyond apices of anterolateral spines. Dorsum with short, very fine setae, unarmed. Pterygostomian flap with strong anterior spine and two subterminal dorsal spines.

Sternum: Plastron broader than long, widening posteriorly. Sternite 3 (at base of maxilliped 3) slightly depressed, anterior margin deeply concave, with V­shaped median notch and pair of median spines, anterolateral angle obtuse, flanked laterally by 1 or 2 short teeth. Sternite 4 (at base of pereopod 1) with serrated lateral margin, anteriorly reaching about to level of median spines of sternite 3.

Abdomen: Segments smooth. Telson about half as long as broad; distal portion posteriorly emarginate, longer than proximal portion.

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

Antenna: Basal segment with distinct outer spine. Peduncle extending beyond midlength of rostrum. Flagellum about 1.5 times as long as peduncle. Ultimate segment about 1.5 times as long as penultimate segment, both with distal spine. Antennal scale wider than opposite peduncular segments, extending to or beyond apex of ultimate peduncle segment.

Maxilliped 3: Dactylus and propodus unarmed. Carpus with distal extensor spine. Merus with 2–4 distal flexor spines and 1 or 2 distal extensor spines. Crista dentata evenly denticulate for entire length of ischium, not extending onto basis.

Pereopod 1 (cheliped): Stout, subcylindrical, setose, about 2.5 times carapace length. Propodus almost glabrous; palm 2.5 times as long as high, about twice as long as pollex. Fingers crossing, occlusal margins dentate and each with low process proximally. Carpus longer than merus, shorter than propodal palm; with small spinules distally; serrate on inner margin. Merus with setose scales and acute tubercles on inner margin, distal margin spinose. Ischium with small distolateral spine.

Pereopods 2–4: Setose, similar, slightly decreasing in length posteriorly. Propodi slightly broadened distally, with 6–9 movable spines on distal flexor margin, distalmost paired. Dactyli with 9–11 fixed, strong, obliquely directed, corneous teeth on flexor margin. Pereopods 2–3 carpus about two­thirds merus and propodus length. Pereopod 4 carpus about 0.8 merus length, 0.6 propodus length.

Ovum : 1.2 mm diameter.

Etymology. Named paracrassior alluding to the strong similarity to U. crassior Baba, 1990 .

Remarks. Uroptychus paracrassior n. sp. and U. crassior Baba, 1990 , from Madagascar, closely resemble each other, particularly in the elongate eyestalks, spination of the maxillipeds and antennal peduncles, the robust, setose chelipeds, the shape of sternites 3 and 4, and spination of the dactyli of the walking legs. Uroptychus paracrassior is readily distinguished from U. crassior by its shorter antennal scale. In U. paracrassior , the antennal scale reaches slightly beyond the apex of the distal peduncle segment, but in U. crassior , the antennal scale exceeds the distal peduncle segment by about half the length of the peduncle.

Uroptychus paracrassior , Uroptychus calcar n. sp., and U. zeidleri n. sp. resemble each other superficially in the glabrous carapace with strong marginal spines. The former is readily distinguished from the latter two in lacking epigastric spines on the carapace and in bearing a pair of small median spines flanking the median notch of sternite 3.

Distribution. Presently known only from northeast of Tweed Heads, southern Queensland, at depths of 364– 380 m.

Figures

FIGURE 19. Uroptychus paracrassior n. sp., holotype female, 7.0 mm, AM P31408. A, dorsum. B, anterior carapace, right lateral. C, cheliped, proximal right ventral. D, telson. E, sternum. F, maxilliped 3, right lateral. G, crista dentata, right. H, antenna, right ventral. A–C = 2 mm, D–H = 1 mm.