Uroptychus australis ( Henderson, 1885 )

Ahyong, Shane T. & Poore, Gary C. B., 2004, The Chirostylidae of southern Australia (Crustacea: Decapoda: Anomura), Zootaxa 436 (1), pp. 1-88 : 18-21

Uroptychus australis ( Henderson, 1885) ( Fig. 3 )

Diptychus australis Henderson, 1885: 420 [type localities: Port Jackson , Kermadec Islands, and Banda, Indonesia].

Uroptychus australis . – Henderson, 1888: 179–180, pl. 21: figs. 4a–c.– Davie, 2002: 29, 31.

Material examined. NEW SOUTH WALES: AM P67835, 1 female (9.5 mm), off Newcastle, 32°49.3’E, 152°49.1’E, 951–1150 m, NZOI U223 , RV Tangaroa, R. Springthorpe & W. Ponder , 10 Oct 1982 ; AM P26759, 2 males (9.5–9.7 mm), 3 females (8.6–8.9 mm), SE of Newcastle, 33°09’S, 152°25’E, 732 m, K77­23­10, 7 Dec 1977 ; AM P31516, 3 males (7.3–8.5 mm), 10 females (8.5–9.3 mm), E of Norah Head , 33°26’S, 152°06’E, 458–476 m, K80­20­06, 9 Dec 1980 ; AM P31494, 2 females (8.3–9.3 mm), E of Terrigal , NSW, 33°27’S, 152°09’E, 897 m, K77­23­13, 8 Dec 1977 ; AM P21071, 1 male (10.7 mm), E of Broken Bay , 33°32–38’S, 152°00–04’E, 824 m, demersal trawl, K75­05­05, 19 Aug 1975 ; AM P21004, 8 males (9.1–10.4 mm), 11 females (9.2–11.8 mm), E of Broken Bay , 33°32–38’S, 152°00–04’E, 824 m, demersal trawl, K75­05­05, 19 Aug 1975 ; AM P31492, 31 males (5.4–10.2 mm), 25 females (7.4–9.5 mm), E of Broken Bay , 33°31– 34’S, 152°02–04’E, 915 m, K77­23­07, 6 Dec 1977 ; AM P19082, 3 males (9.9–11.7 mm), E of Port Jackson , 33°52’S, 151°50’E, 778 m, K72­07­15, 7 Dec 1972 ; AM P25233, 3 females (7.7–10.8mm), NE of Wollongong , 34°24’S, 151°25’E, 768 m, K76­23­01, 13 Dec 1976 ; NMV J52353 (part), 1 male (9.9 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 ; NMV J17055 (part), 1 male (10.3 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 P67836, 1 male (11.6 mm), 5 females (8.5–10.1 mm), E of Ulladulla , 35°27’S, 150°55’E, 987–1025 m, K83­14­02, 25 Oct 1983 .

VICTORIA: NMV J14229 , 12 males (7.5–10.5 mm), 7 females (8.3–10.4 mm), S of Point Hicks , SLOPE 33 , M. Gomon et al .

TASMANIA: AM P64989, 3 males (10.6–11.1 mm), 5 females (8.6–9.9 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 ; NMV J52352 , 1 ovigerous female (9.6 mm), 39 km NE of Cape Tourville, Freycinet Peninsula , 41°53.54–53.31’S, 148°39.07–38.82’E, 732– 626 m, 3.5 m beam trawl, G. Poore et al., 30 Oct 1988; J52354 , 2 males (9.2–10.9 mm), 39 km NE of Cape Tourville , SLOPE 84 , G. Poore et al .

Diagnosis. Carapace excluding rostrum distinctly longer than broad; lateral margins unarmed; posterior quarter with low ridge; dorsum unarmed, at most with pair of small epigastric tubercles. Rostrum sharply triangular. Sternite 3 strongly depressed, anterior margin narrow, deeply emarginate, with pair of median spines. Antennal basal segment with distinct outer spine; ultimate and penultimate segments unarmed. Antennal scale slightly shorter to slightly longer than peduncle. Cheliped merus usually with cluster of tubercles on inner proximal margin. Pereopods 2–4 dactyli with spines on flexor margin oriented parallel to dactylar margin. Pereopod 4 markedly shorter than pereopod 3; length of pereopod 4 merus about half that of pereopod 3.

Description. Carapace: Distinctly longer than broad. Lateral margins subparallel, uneven, irregular behind base of cervical groove; posterior quarter with low ridge. Rostrum sharply triangular, exceeding one­third length of remaining carapace, margins unarmed. Anterolateral spine small; outer orbital angle produced to small acute spine extending beyond level of anterolateral spine. Dorsum smooth and unarmed, at most with pair of small epigastric tubercles. Pterygostomian flap with small anterior spine.

Sternum: Plastron broader than long, widening posteriorly. Sternite 3 (at base of maxilliped 3) strongly depressed, anterior margin narrow, deeply emarginate, with pair of median spines; outer lobes of emargination obtusely angled. Sternite 4 (at base of pereopod 1) with distinct anterolateral tooth extending anteriorly to level of base of emargination of sternite 3; margins tuberculate, irregular.

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 quarter of rostrum. Flagellum about twice as long as peduncle. Ultimate and penultimate segments unarmed; ultimate segment about 2.5 times length of penultimate segment. Antennal scale wider than opposite peduncular segments, slightly shorter to slightly longer than peduncle.

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, about 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 4 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 usually with cluster of tubercles on inner proximal margin, less pronounced in juveniles. Ischium with triangular spine on outer margin.

Pereopods 2–4: Sparsely setose. Meri dorsal margin proximally irregular. Propodi not broadened distally, with 6–8 movable spines on distal flexor margin, distalmost paired. Dactyli setose marginally; with 7–9 small, fixed spines on flexor margin, distal 2 most prominent, proximal spines oriented parallel to dactylar margin. Pereopods 2–3 similar, carpus about 0.5 merus length, about 0.6 propodus length. Pereopod 3 slightly longer than pereopod 2. Pereopod 4 markedly shorter than pereopod 3; length of pereopod 4 merus about half that of pereopod 3.

Ovum : 1.4 mm diameter.

Remarks. Uroptychus australis ( Henderson, 1885) is the most common species of the genus off eastern Australia but has never been adequately described. Of the Australian species, U. australis most closely resembles U. empheres n. sp., and U. gracilimanus ( Henderson, 1885) but differs from both in having the spines on the flexor margin of the dactyli of pereopods 2–4 oriented parallel to, instead of oblique to the dactylar margin. Uroptychus australis further differs from U. empheres in having larger tubercles on the proximal flexor margin of the cheliped merus and in lacking the field of granules on sternite 4. Uroptychus australis further differs from U. gracilimanus in having the antennal scale longer instead of distinctly shorter than the antennal peduncle, in having a shorter merus of pereopod 4 (half instead of two­thirds that of pereopod 3), and in having a deeper concavity on the anterior margin of the sternum. In his key to selected species of the Uroptychus, Baba (1988) used the presence of tubercles on the inner margin of the merus of the chelipeds to distinguish U. australis from U. gracilimanus and several other species. Uroptychus empheres and U. gracilimanus , however, also bear tubercles on the inner margin of the merus of the chelipeds, although smaller and usually less distinct.

As in U. gracilimanus , females and juveniles of U. australis often bear more slender chelae than adult males. Aside from the sexual dimorphism sometimes present in the chelae of U. australis , variation between specimens is slight. Most specimens bear a pair of minute epigastric tubercles on the carapace, and the scaphocerite varies from about as long as to longer than the antennal peduncle.

The syntypes of U. australis were collected at three different localities: off Port Jackson, the Kermadec Islands, and Banda, Indonesia. Davie (2002) fide Baba (pers. com.) indicated that the syntype series of U. australis comprises three separate species of which two are undescribed. Therefore, the identity of U. australis must ultimately be fixed by lectotype designation (Baba, in prep., fide Davie 2002). Our specimens, however, are referred to U. australis because they agree well with Henderson’s (1885, 1888) accounts and figures including the tuberculate inner margins of the cheliped merus and short merus of pereopod 4. A topotypic specimen of U. australis , collected off Port Jackson, is illustrated ( Fig. 3 ).

Distribution. Indonesia, the Kermadec Islands and northern New South Wales, south to Victoria and Tasmania at 458–1150 m depth.

Figures

FIGURE 3. Uroptychus australis (Henderson, 1885), male, 11.7 mm, off Port Jackson, AM P19082. 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 = 3.5 mm, D–F = 1.8 mm, G–H = 0.9 mm.