Uroptychus jawi, Mccallum, Anna W. & Poore, Gary C. B., 2013

Mccallum, Anna W. & Poore, Gary C. B., 2013, Chirostylidae of Australia’s western continental margin (Crustacea: Decapoda: Anomura), with the description of five new species, Zootaxa 3664 (2), pp. 149-175 : 162-164

Uroptychus jawi sp. nov.

( Fig. 7 )

Type material. Holotype: Female (cl 9.2 mm), Western Australia, north-western Australia, off Cape Leveque (14°33.43'S, 121°20.38'E – 14°32.76'S, 121°19.65'E), 924–1101 m, 4 Jul 2007 (stn SS05/2007 156), CSIRO acquisition number 0 12, NMV J61765 .

Diagnosis. Carapace excluding rostrum as long as broad; width between anterolateral margins 0.65 times that of broadest carapace width at posterior 0.7; lateral margins convex, with irregular tubercles along margin; outer orbital angle produced to small spine. Dorsum unarmed. Rostrum sharp triangular, horizontal, about half the length of remaining carapace. Sternite 3 anterior margin deeply concave, with pair of submedian spines separated by narrow U-shaped notch. Sternite 4 surface with a transverse row of tubercles and setae. Antennal peduncle ultimate and penultimate articles unarmed; ultimate article about twice length of penultimate article; antennal scale extending slightly beyond midlength of ultimate peduncle article. Pereopod 1 merus and ischium smooth on inner proximal margin. Pereopods 2–4 propodi not broadened distally, with 4–5 movable spines on distal flexor margin, distalmost paired; dactyli with 10 obliquely directed spines on flexor margin, ultimate and penultimate spines subequal. Pereopod 2 slightly longer than pereopod 3; length of pereopod 3 merus 0.9 that of pereopod 2. Pereopod 4 shorter than pereopod 3 merus; length of pereopod 4 merus about 0.8 that of pereopod 3 merus.

Description. Carapace: Carapace excluding rostrum as long as broad; width between anterolateral margins 0.65 times that of broadest carapace width at posterior 0.7; lateral margins convex; with granules and scattered setae, irregularly rugose behind base of cervical groove; distinct ridge along posterior fifth of length. Anterolateral spine overreaching small outer orbital spine; dorsal surface with feeble depression between indistinct gastric and cardiac regions, smooth and without setae; gastric region without epigastric spines or granulate epigastric ridges. Rostrum sharp triangular, 1.3 times as long as broad, horizontal; dorsal surface flat, half the length of remaining carapace. Pterygostomian flap anterior margin rounded, with small spine.

Sternum: Sternal plastron 1.2 times as long as broad, slightly widening posteriorly. Sternite 3 anterior margin deeply concave, with pair of submedian spines separated by narrow U-shaped notch; lateral margin with short spines. Sternite 4 with blunt anterolateral tooth not extending anteriorly beyond sternite 3 median spines; surface with a transverse row of tubercles and setae.

Abdomen: Somites glabrous. Telson length about 0.6 breadth; distal portion posteriorly emarginate, about twice length of proximal portion.

Eyes: Cornea as wide as peduncle, slightly shorter than length of peduncle; reaching to distal third of rostrum.

Antenna: Peduncle extending to distal third of rostrum. Basal segment with outer spine; ultimate and penultimate articles unarmed; ultimate article 1.7 times length of penultimate article. Antennal scale 1.3 times broader than article 5, extending slightly beyond midlength of ultimate peduncle article.

Maxilliped 3: Dactylus, propodus, carpus and merus unarmed. Crista dentata distinctly serrate with 18 denticles. Basis with 4 denticles on mesial ridge.

Pereopod 1 (cheliped): Chelipeds unequal; right larger; 2.7 (left) or 2.9 (right) times carapace length (holotype with chelipeds of slightly different size); glabrous dorsally and sparsely setose. Propodus palm 2.7 times as long as high, 1.4 times as long as pollex. Fingers crossing, occlusal margins finely dentate; occlusal margin of dactylus with bilobed process proximally; occlusal margin of pollex without distinct process. Carpus 1.1 times as long as merus and 1.2 times propodal palm, with a few setae; merus and ischium smooth on inner proximal margin; ischium with stout curved spine on outer distal margin.

Pereopods 2–4: Sparsely setose, setae on propodi and distal parts of carpi very long. Propodi not broadened distally, flexor margin ending in pair of spines preceded by 5 (on P2 and P3), and 4 (on P4) movable spines on distal half. Dactyli with 10 fixed, obliquely directed triangular spines on flexor margin, ultimate and penultimate subequal. Pereopods 2–3 similar; carpus and merus unarmed; carpus 0.6 merus length, 0.7 propodus length. Pereopod 2 slightly longer than pereopod 3; pereopod 3 merus 0.9 length of pereopod 2 merus. Pereopod 4 shorter than pereopod 3; pereopod 4 merus 0.8 length of pereopod 3 merus; carpus 0.6 propodus length.

Etymology. After the indigenous Jawi ‘sea people’ of the Dampier Peninsula (noun in apposition).

Distribution. North-western Australia, off Cape Leveque, 924–1101 m.

Remarks. This new species most closely resembles Uroptychus orientalis Baba & Lin, 2008 from the West Pacific. Uroptychus jawi can be distinguished from U. orientalis by the rostrum which is dorsally upturned in U. orientalis and horizontal in U. jawi . Also, U. orientalis has low spines on the ventral surface of the pereopod 1 merus, and a pair of granular ridges on the epigastric region, both of which are absent in U. jawi . U. jawi resembles U. brucei Baba, 1986 from north-western Australia but can be distinguished by the number of spines on the flexor margin of the propodi of the walking legs which are more numerous in U. brucei (17–19) than U. jawi (4–5). U. jawi is also similar to the Australian species: U. bardi sp. nov., U. taylorae sp. nov., and U. litosus , but all these species have a much longer antennal scale, which reaches or exceeds the apex of the ultimate peduncle article. The holotype has unequal chelipeds; this has also been reported from some specimens of U. brucei and U. comptus Baba, 1988 .

Figures

FIGURE 7. Uroptychus jawi sp. nov., female (9.2 mm), NMV J 61765. A, carapace and abdomen with pereopods 2 – 5, dorsal. B, carapace, lateral. C, sternum. D, right antenna, ventral. E, maxilliped 3, merus and ischium, right, lateral. F, maxilliped 3 basis and ischium, right, ventral. G, pereopod 1, left. H, pereopod 1, right, distal part. Scales: A, G, H = 5 mm, C – F = 1 mm.