Uroptychus gracilimanus ( Henderson, 1885 )

Ahyong, Shane T. & Poore, Gary C. B., 2004, The Chirostylidae of southern Australia (Crustacea: Decapoda: Anomura), Zootaxa 436 (1), pp. 1-88 : 40-44

Uroptychus gracilimanus ( Henderson, 1885) ( Fig. 10 )

Diptychus gracilimanus Henderson, 1885: 420 [type locality: off Port Jackson , New South Wales, Australia].

Uroptychus gracilimanus .– Henderson, 1888: 181, pl. 21: fig. 5.– Tirmizi, 1964: 392, figs. 6–9.– Baba, 1969: 45, figs. 3,4; 1988: 19, 35–36; 1990: 924, 941–943, figs. 8a, b.– Davie, 2002: 31.

Material examined. NEW SOUTH WALES: AM P64924, 4 males (7.8–12.1 mm), 8 females (7.9–11.9 mm), off Newcastle, 1040–1075 m, NZOI Y222 , RV Tangaroa, R. Sprinthorpe & W. Ponder , 9 Oct 1982 ; AM P67833, 2 males (10.9–12.1 mm), 6 females (9.3–11.4 mm), off Newcastle, 32°49.3’S, 152°49.1’E, 951–1150 m, NZOI U223 , RV Tangaroa, R. Sprinthorpe & W. Ponder , 10 Oct 1982 ; AM P31511, 1 female (7.5 mm), E of Norah Head , 33°26’S, 152°06’E, 458–476 m, K80­20­06, 9 Dec 1980 ; AM P65824, 1 male (8.3 mm), 1 female (8.1 mm), E of Broken Bay , 33°31–34’S, 152°02–04’E, 915 m, K77­23­07, 6 Dec 1977 ; AM P65825, 1 female (9.4 mm), E of Port Jackson , 33°52’S, 151°50’E, 778 m, K72­07­15, 7 Dec 1972 ; NMV J52353 (part), 2 females (9.8–11.6 mm), 56 km ENE of Nowra, 34°43.95–43.98’S, 151°14.74–14.28’E, 1009– 817 m, SLOPE 58 , 3.5 m beam trawl, G. Poore et al., 22 Oct 1988 ; AM P65627, 1 female (11.8 mm), E of Shoalhaven Bight , 34°54–56’S, 151°15–17’E, 1115–1152 m, K83­18­02, 30 Nov 1983 ; NMV J17055 (part), 1 male (12.2 mm), 2 ovigerous females (11.5–12.2 mm), off Nowra , 35°00.00’S, 151°16.30’E, 1100 m, SLOPE 9 , 5 m otter trawl, M. Gomon et al., 15 Jul 1986 ; AM P67837, 2 males (7.5–12.0 mm), 1 ovigerous female (11.0 mm), E of Ulladulla , 35°27’S, 150°55’E, 987–1025 m, K83­14­02, 25 Oct 1983 .

VICTORIA: NMV J17060 , 1 male (10.7 mm), 1 ovigerous female (9.9 mm), 63 km S of Point Hicks, Bass Strait , 38°22.66’S, 149°18.41’E, 1073 m, 3.5 m beam trawl , SLOPE 68 , G. Poore et al., 25 Oct 1988 ; NMV J52350 , 1 male (9.5 mm), 2 ovigerous females (8.0– 9.2 mm), 63 km S of Point Hicks, Bass Strait , 38°22.66’S, 149°18.41’E, 1073 m, 3.5 m beam trawl , SLOPE 68 , G. Poore et al., 25 Oct 1988 .

TASMANIA: NMV J52351 , 1 male (8.1 mm), 48 km ENE of Cape Tourville , SLOPE 81 , G. Poore et al.; SAM, 1 ovigerous female (11.0 mm), 67 km SSE of Southeast Cape , 44°11.9’S, 147°04.7’E, 1025–1116 m, trawl, FV Corvina, K. Gowlett­Holmes , 8 Feb 1992 ; AM P64988, 1 female (11.1 mm), off St. Patricks Head , 41°37.3–39.8’S, 148°41.4– 40.5’E, 940–990 m, S05/87/06, K. Graham, 11 Jul 1987 .

Diagnosis. Carapace excluding rostrum distinctly longer than broad; lateral margins subparallel or slightly divergent, unarmed; with small anterolateral spine; posterior quarter with low but distinct ridge; outer orbital angle produced to small spine; dorsum smooth and unarmed, except for pair of small epigastric spines or tubercles. Rostrum sharply triangular. Sternite 3 strongly depressed, anterior margin shallowly emarginate, with narrow Ushaped notch and pair of median spines. Antennal basal segment with distinct outer spine; ultimate and penultimate segments unarmed. Antennal scale extending to or beyond midlength but not beyond distal two­thirds of ultimate peduncle segment. Cheliped merus with tubercles on inner proximal margin. Pereopods 2–4 propodi not broadened distally, with 6–8 movable spines on lower distal margin, none paired; dactyli flexor margin with 9–11 obliquely directed spines. Pereopod 4 distinctly shorter than pereopod 3; length of pereopod 4 merus 0.7–0.8 that of pereopod 3.

Description. Carapace: Length (excluding rostrum) distinctly greater than breadth. Lateral margins subparallel or slightly divergent, unarmed except for small tubercle at base of cervical groove in larger specimens; with small, anteriorly directed anterolateral spine; posterior quarter with low but distinct ridge. Rostrum sharply triangular, exceeding one­third length of remaining carapace, margins unarmed. Outer orbital angle produced to small spine extending slightly beyond level of anterolateral spines. Dorsum smooth and unarmed, except for pair of small epigastric spines or tubercles. Pterygostomian flap with small anterior spine.

Sternum: Plastron about as broad as long, widening posteriorly. Sternite 3 (at base of maxilliped 3) strongly depressed, anterior margin shallowly emarginate, with narrow Ushaped notch and pair of median spines; outer lobes of emargination obtusely angled with short outer projection. Sternite 4 (at base of pereopod 1) with anterolateral tooth not extending anteriorly beyond level of base of median notch; margins tuberculate, irregular; surface with transverse row of tubercles.

Abdomen: Segments glabrous. Telson about two­thirds as long as broad; distal portion posteriorly emarginate, about twice length of proximal portion.

Eye: Cornea moderately dilated, subequal to length of peduncle; reaching to distal quarter of rostrum.

Antenna: Basal segment with distinct outer spine. Peduncle extending to distal third of rostrum. Flagellum about twice as long as peduncle. Ultimate and penultimate segments unarmed; ultimate segment about 2 times length of penultimate segment. Antennal scale wider than opposite peduncular segments, extending to or beyond midlength but not beyond distal two­thirds of ultimate peduncle segment.

Maxilliped 3: Dactylus, propodus, carpus and merus unarmed. Crista dentata distinctly serrate on proximal two­thirds of ischium, extending onto basis.

Pereopod 1 (cheliped): Slender, cylindrical, 3.5–4.0 times carapace length; chelae of females and juveniles usually more slender than in adult males; segments glabrous dorsally and sparsely setose distally. Propodus palm about 3 times as long as high, about twice as long as pollex. Fingers crossing, occlusal margins finely dentate and each; occlusal margin of dactylus with obtuse process proximally; occlusal margin of pollex with low prominence at about midlength. Carpus longer than merus and as long as propodal palm; glabrous. Merus with distinct tubercles on inner proximal margin, less pronounced in juveniles. Ischium with triangular spine on outer margin.

Pereopods 2–4: Sparsely setose. Meri and carpi with smooth margins. Propodi not broadened distally; with smooth extensor margin; with 6–8 movable spines on distal flexor margin, none paired. Dactyli setose marginally, with 9–11 fixed, obliquely directed spines on flexor margin. Pereopods 2–3 carpus about 0.5 merus length, about 0.6 propodus length. Pereopod 2 slightly longer than pereopod 3. Pereopod 4 distinctly shorter than pereopod 3; length of pereopod 4 merus 0.7–0.8 that of pereopod 3.

Ovum : 1.8 mm diameter.

Remarks. Uroptychus gracilimanus ( Henderson, 1885) is most similar to U. australis ( Henderson, 1885) and U. comptus Baba, 1988 . Characters distinguishing the three species are outlined under the account of U. australis . Uroptychus gracilimanus also resembles U. nigricapillis in general habitus including the armature and proportions of the antennal peduncle, antennal scale, walking legs and sternal plastron. Uroptychus nigricapillis is readily distinguished from U. gracilimanus , however, by the presence of several small spines along the lateral carapace margins.

The slenderness of the chelae of U. gracilimanus , the basis for its specific name, is sexually dimorphic as in U. australis , being more robust in adult males. The tubercles on the inner proximal margin of the chelae are also most distinct in adult males. Although not mentioned by Henderson (1885, 1888), a pair of small epigastric spines or tubercles is present on the carapace in U. gracilimanus . Uroptychus gracilimanus has not been adequately described or figured. Therefore, the species is redescribed above and a specimen from the type locality, off Port Jackson (AM P65825), is illustrated in Figure 10 .

Distribution. East Africa, Indonesia, the East China Sea, Japan, eastern Australia and now Tasmania at depths of 421–1668 m.

Figures

FIGURE 10. Uroptychus gracilimanus (Henderson, 1885), female, 9.4 mm, off Port Jackson, AM P65825. 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, F = 2 mm, D–E, G–H = 1 mm.