Uroptychus litosus, 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 : 52-55

Uroptychus litosus n. sp. ( Fig. 14 )

Uroptychus australis .– Poore, Hart, Taylor & Tudge, 1998: 69 [part, not U. australis ( Henderson, 1885) ].

Type material. HOLOTYPE: NMV J52862 , male (17.8 mm), “ Andys ” Seamount, 65.5 km SSE of SE Cape, Tasmania, 44°10.8’S, 147°00.0’E, 800 m, epibenthic sled, SS01/97/ 56, T. Stranks et al., 29 Jan 1997; PARATYPES: NMV J39631 , 2 males (18.2–19.0 mm), 1 ovigerous female (16.1 mm), “ Andys ” Seamount, Tasmania, 65.5 km SSE of SE Cape, 44°10.8’S, 147°00.0’E, 800 m, epibenthic sled, SS01/97/56, T. Stranks et al., 29 Jan 1997; NMV J44742 , 3 males (13.9–19.8 mm), 11 females (7.9–17.1 mm), “ Andys ” Seamount, Tasmania, 65.5 km SSE of SE Cape, 44°10.8’S, 147°00.0’E, 800 m, epibenthic sled, SS01/97/56, T. Stranks et al., 29 Jan 1997; SAM C6062 , 3 males (11.1–17.5 mm), 1 female (15.8 mm), 81 km SSE of Southeast Cape, Tasmania, 44°15.2’S, 147°21.2’E, 1050–1120 m, clinging to coral, FV Belinda, K. Gowlett­Holmes, 12 Feb 1992; SAM C6060 , 1 male (18.2 mm), 86 km NE of Babel Island, Tasmania, 39°15.94’S, 148°49.55’E, 1017–1042 m, demersal trawl, S03/89/43, FV Soela, 20 Apr 1989; SAM C6059 , 2 females (14.8–15.7 mm), 70 km SSE of Southeast Cape, Tasmania, 800–950 m, off gold bamboo coral with base 8–10 inches in diameter, FV Belinda , K. Gowlett­ Holmes , 10 Feb 1992; SAM C6061 , 1 male (18.4 mm), 67 km SSE of Southeast Cape, Tasmania, 44°11.9’S, 147°04.7’E, 1025–1116 m, trawl, FV Corvina, K. Gowlett­Holmes, 8 Feb 1992.

Diagnosis. Carapace excluding rostrum as long as broad; lateral margins distinctly convex, broadest posterior to midlength; with irregular tubercles along margin; with anterolateral spine; outer orbital angle produced to small spine; dorsum unarmed, except for short row of small epigastric tubercles behind each orbit (in adults). Rostrum sharply triangular, about one­third length of remaining carapace. Sternite 3 strongly depressed, anterior margin shallowly emarginate, with narrow U­shaped notch and pair of median spines. Basal segment with distinct outer spine; ultimate and penultimate segments unarmed; ultimate segment about twice length of penultimate segment; antennal scale extending about to or slightly beyond apex of ultimate peduncle segment. Cheliped robust; merus and ischium with distinct tubercles on inner proximal margin. Pereopods 2–4 propodi not broadened distally, with movable spines on distal flexor margin, distalmost paired; dactyli with 10–12 obliquely directed spines on flexor margin. Pereopod 4 shorter than pereopod 3; length of pereopod 4 merus about 0.75 that of pereopod 3.

Description. Carapace: Carapace excluding rostrum as long as broad. Lateral margins distinctly convex, broadest posterior to midlength; with irregular tubercles along margin; with distinct, anteriorly directed anterolateral spine; posterior fifth with low but distinct ridge. Rostrum sharply triangular, about one­third length of remaining carapace, margins unarmed. Outer orbital angle produced to small spine not extending slightly beyond level of anterolateral spines. Dorsum smooth and unarmed, except for short row of small epigastric tubercles behind each orbit (in adults). Pterygostomian flap with distinct anterior spine.

Sternum: Plastron about as broad as long, slightly 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 apices of median spines; margins tuberculate, irregular.

Abdomen: Segments glabrous. Telson length about 0.6 breadth; 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 twice length of penultimate segment. Antennal scale wider than opposite peduncular segments, extending about to or slightly beyond apex of ultimate peduncle segment.

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

Pereopod 1 (cheliped): Robust, slightly compressed; about 3 times carapace length; segments glabrous dorsally and sparsely setose distally. Propodus palm about twice as long as high, about twice as long as pollex. Fingers crossing, occlusal margins finely dentate and each; occlusal margin of dactylus with 2 obtuse processes proximally; occlusal margin of pollex with low prominence distal to midlength. Carpus longer than merus and as long as propodal palm; glabrous. Merus and ischium with distinct tubercles on inner proximal margin, less pronounced in juveniles; ischium with curved spine on outer margin.

Pereopods 2–4: Sparsely setose. Propodi not broadened distally, with 10–13 movable spines on distal flexor margin, distalmost paired. Dactyli setose marginally, with 10–12 fixed, obliquely directed spines on flexor margin. Pereopods 2–3 similar; carpus and merus dorsal unarmed; carpus about 0.6 merus length, about 0.7 propodus length. Pereopod 2 slightly longer than pereopod 3. Pereopod 4 shorter than pereopod 3; length of pereopod 4 merus about 0.75 that of pereopod 3; carpus about 0.7 merus and propodus length.

Ovum : 1.5 mm diameter.

Etymology. The specific name is derived from the Greek word litos, meaning plain, alluding to the relatively simple, nondescript features of the species.

Remarks. Uroptychus litosus n. sp. resembles U. nitidus occidentalis Faxon, 1893 , in carapace shape, presence of tubercles on the inner proximal margin of the merus of the cheliped, armature of the dactyli of pereopods 2–4, and the shape of the anterior sternites as figured by Baba (1973). Uroptychus litosus differs from U. nitidus occidentalis in having the ultimate antennal segment about twice as long instead of being as long as the penultimate segment, and the antennal scale is as long as or longer than the antennal peduncle instead of being distinctly shorter. Uroptychus litosus also resembles U. australis and U. gracilimanus in bearing distinct tubercles on the inner proximal margin of the merus of the cheliped and paired submedian spines on the anterior margin of the third sternite. The new species differs in numerous features including the carapace shape, being distinctly broadened posteriorly, and the distinctly more robust chelae. Uroptychus litosus further differs from U. australis and resembles U. gracilimanus in having the merus of pereopod 4 distinctly longer than half that of pereopod 3, and in having the spines on the flexor margins of the pereopod 2–4 dactyli upright instead of aligned parallel to the dactylar margins.

Part of the material reported by Poore et al. (1998) from the Tasmanian seamounts as U. australis is referable to U. litosus .

Distribution. Southern Tasmania in the vicinty of “Andys” Seamount at depths of 800–1120 m.

Figures

FIGURE 14. Uroptychus litosus n. sp., holotype male, 17.8 mm, NMV J52862. A, dorsum. B, anterior carapace, right lateral. C, cheliped merus, right ventral. D, cheliped merus, right lateral. E, telson. F, sternum. G, maxilliped 3, right lateral. H, crista dentata, right. I, antenna, right ventral. A– B = 5 mm, C–G = 2.5 mm, H–I = 1.3 mm.