Uroptychus babai, 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 : 22-25

Uroptychus babai n. sp. ( Fig. 4 )

Uroptychus granulatus .– Baba, 1990: 923, 943–944, fig. 9 [not U. granulatus Benedict, 1902 ].

Type material. HOLOTYPE: AM P26782, male (14.1 mm), E of Broken Bay , New South Wales, 33°31–34’S, 152°02–04’E, 905–914 m, demersal trawl, K77­23­07, 6 Dec 1977 . PARATYPES: AM P67834, 1 male (15.5 mm), 1 female (16.5 mm), off Newcastle, 32°49.3’S, 152°49.1’E, 951–1150 m , NZOI U223 , RV Tangaroa, R. Springthorpe & W. Ponder , 10 Oct 1982 ; AM P53248, 1 male (18.2 mm), 1 female (15.4 mm), E of Broken Bay , New South Wales, 33°28–31’S, 152°12–14’E, 951–1006 m, demersal trawl, K81­15­ 03, 3 Nov 1983 ; AM P65883, 2 ovigerous females (16.8–18.2 mm), E of Shoalhaven Bight , New South Wales, 34°54’S, 151°17’E, 1115–1152 m, K83­18­02, 30 Nov 1983 ; NMV J17065 , 1 male (13.0 mm), 1 female (17.3 mm), off Nowra , New South Wales, 35°00.00’S, 151°16.30’E, 1100 m , SLOPE 9 , 5 m otter trawl, M. Gomon et al., 15 Jul 1986 ; AM P65832, 1 female (17.0 mm), E of Ulladulla , New South Wales, 35°27’S, 150°55’E, 987–1025 m, on crinoid Glyptometra inaequalis ( AM J18867 ), K83­14­02, 25 Oct 1983 .

Diagnosis. Carapace excluding rostrum slightly broader than long; lateral margins irregular, crenulate, distinctly convex, broadest posterior to midlength; with distinct, anteriorly directed anterolateral spine; posterior quarter with low ridge. Rostrum sharply triangular; dorsum unarmed. Sternite 3 anterior margin with broad V­shaped emargination. Basal antennal segment with distinct outer spine; ultimate and penultimate segments unarmed. Antennal scale extending beyond apex of ultimate peduncle segment. Pereopods 2–4 propodi not broadened distally, with 1 or 2 movable spines on lower distal margin; dactyli lined with 15–20 small, close­set, obliquely inclined spines on flexor margin, penultimate markedly broader than others.

Description. Carapace: Slightly broader than length (excluding rostrum). Lateral margins irregular, crenulate, distinctly convex, broadest posterior to midlength; with distinct, anteriorly directed anterolateral spine; posterior quarter with low ridge. Rostrum sharply triangular, about half length of remaining carapace, margins unarmed; dorsum sparsely setose or naked. Outer orbital angle produced to triangular tooth, not extending beyond anterolateral spine. Dorsum carapace sparsely­setose, unarmed. Pterygostomian flap with triangular anterior spine.

Sternum: Plastron about as broad as long, slightly widening posteriorly. Sternite 3 (at base of maxilliped 3) not depressed, anterior margin with broad V­shaped emargination; outer lobes of emargination obtusely angled, flanked by short projection. Sternite 4 (at base of pereopod 1) with obtuse anterolateral margin, extending anteriorly to about midlength of emargination of sternite 3.

Abdomen: Segments sparsely setose. 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 reaching to proximal half of rostrum.

Antenna: Basal segment with distinct outer spine. Flagellum about twice as long as peduncle. Ultimate and penultimate segments unarmed; ultimate segment about twice length of penultimate segment. Antennal scale wider than opposite peduncular segments, extending beyond apex of ultimate peduncle segment.

Maxilliped 3: Dactylus, propodus, carpus and merus unarmed. Crista dentata evenly serrate on proximal three­quarters of ischium, not extending onto basis.

Pereopod 1 (cheliped): Slender, rugose with setose scales, subcylindrical; about 3 times carapace length. Propodus with palm about 3.5 times as long as high, about twice as long as pollex. Fingers crossing, occlusal margins finely dentate; occlusal margin of dactylus with obtuse process proximally; occlusal margin of pollex with low prominence at midlength. Carpus longer than merus and as long as propodal palm. Ischium with triangular spine on outer margin.

Pereopods 2–4: Setose, similar, becoming shorter distally. Carpi and meri unarmed. Propodi not broadened distally, with 1 or 2 movable spines on distal flexor margin. Dactyli lined with 15–20 small, close­set, obliquely inclined, fixed spines on flexor margin, penultimate markedly broader than others. Carpus of pereopods 2–3 about 0.4 merus and 0.5 propodus length; carpus of pereopod 4 about 0.5 merus length, about 0.4 propodus length.

Ovum : 1.3 mm diameter.

Etymology. Named for Keiji Baba, Kumamoto University, Japan, for his foundational work on the systematics of the Galatheidea.

Remarks. Uroptychus babai n. sp. closely resembles U. granulatus Benedict, 1902 , from the Galapagos Islands. The two species agree in almost all respects, but U. babai differs in having crenulate or irregular instead of spinose lateral carapace margins, the basal antennal segment bears a distinct outer spine, a short median notch is present in the anterior concavity of sternite 3 and the anterolateral angles of sternite 4 are bluntly rounded instead of acute. Baba (1990) reported and figured material identified as U. granulatus from Madagascar in which the lateral carapace margins are irregular or crenulate but not spinose as in the holotype from the Galapagos Islands. Based on Baba’s (1990) account, the specimens from Madagascar are referable to U. babai , and significantly extend the range of the species. Uroptychus babai also resembles U. bacillimanus Alcock & Anderson, 1899 , and U. valdiviae Doflein & Balss, 1913 , both from the eastern Indian Ocean, in the shape of the carapace, and limb proportions. Uropotychus babai is readily distinguished from U. bacillimanus in having well­developed instead of minute anterolateral spines on the carapace and in having the antennal scale longer instead of distinctly shorter than the antennal peduncle. The strong anterolateral spine and well­developed outer orbital spine of the carapace will readily distinguish U. babai from U. valdiviae .

Of the regional Uroptychus species , U. babai resembles two New Zealand species, U. maori Borradaile, 1916 , and U. tomentosus Baba, 1974 , in carapace shape and overall habitus. Uroptychus babai is readily distinguished from U. tomentosus in the length of the antennal scale (longer than instead of shorter than the antennal peduncle) and in having a small triangular tooth instead of long falcate spine on the dorsal distal margin of the ischium of the cheliped. Uroptychus babai chiefly differs from U. maori in the length of the antennal scale (longer than instead of distinctly shorter than the antennal peduncle), in lacking an inner distal spine on the penultimate antennal peduncle segment, and in having 15–17 instead of 6 spines on the flexor margin of the dactyli of pereopods 2–4.

Distribution. Southeastern Australia at depths between 905 and 1150 m, and Madagascar at 880–920 m ( Baba, 1990).

Figures

FIGURE 4. Uroptychus babai n. sp., holotype male, 14.1 mm, AM P26782. A, dorsum. B, anterior carapace, right lateral. C, cheliped merus, proximal right ventral. D, telson. E, sternum. F, maxilliped 3, right lateral. G, crista dentata, right. H, antenna, right ventral. Scale A–C = 4 mm, D–F = 2 mm, G–H = 1 mm.