Rhinoecetes setosus, Just, 2019

Just, Jean, 2019, Siphonoecetini Just, 1983 (Crustacea, Amphipoda, Ischyroceridae) 13: Western Australian species of Bubocorophiina in Rhinoecetes, Cephaloecetes, Sinoecetes, Borneoecetes and Pararhinoecetes gen. nov., Zootaxa 4554 (1), pp. 101-140 : 126-128

Rhinoecetes setosus sp. nov.

Figures 17–18

Type fixation. Holotype, male, here designated.

Etymology. The species is named for the densely setose articles 4 and 5 of antenna 2 in adult males.

Material examined. Holotype. ♂, 3.0 mm. Western Australia, Cape Range National Park, inside Ningaloo Reef off Ned’s Camp , 21°59.5’S 113°54.5’E, 2 m, sand, J.K. Lowry, stn WA-347, 1 January 1984, AM P35077.

Paratypes. Same sample as holotype, AM P 101865 (> 100 specimens) . Same sample as holotype, WAM C73464 (7, ♂ and ♀) . Same sample as holotype, NHMD-233160 (8 specimens) . Western Australia, Cape Range National Park, inside Ningaloo Reef off Ned’s Camp , 21°59.5’S 113°54’E, 2 m, small brown algae, R.T. Springthorpe, 1 January 1984, AM P34976 (2 small specimens). Western Australia, Cape Range National Park , inside Ningaloo Reef off Ned’s Camp, 21°59.5’S 113°54.5’E, airlift, R.T. Springthorpe, 1 January 1984, AM P34977 (ca. 60 specimens) . Western Australia, Cape Range National Park, channel in Ningaloo Reef off Ned’s Camp , 21°59’S 113°54.5’E, 6 m, rock scrapings, filamentous algae, sand, strong surge, J.K. Lowry, stn WA-325, 31 December 1983, AM P35075 (1 small specimen) .

Description (holotype, ♂). Head as long as pereonites 1 and 2 combined along dorsal midline; mid-anterior depression moderately deep, encompassing approximately 0.5 head length. Rostrum straight, acutely pointed, in dorsal view reaching beyond apices of eye lobes nearly entire length. Front margin lateral to rostrum with moderately overhanging ‘brows’. Eye lobes broadly rounded in lateral view, with angular lower anterior corner; lower distal margin with a few simple setae.

Antenna 1 approximately as long as head and pereonites 1–5 combined, reaching to proximal 0.25 of antenna 2 peduncle article 5; flagellum of 6+ articles, as long as peduncle articles 1–2 and half of 3 combined, peduncle article 1 medial and lateral margins parallel in dorsal view. Antenna 2 approximately as long as head, all pereonites, and pleonites 1–3 combined; ventral projection of peduncle article 2 approximately as long as broad at base, tapering to rounded apex, with fringe of long simple setae laterally and apically; peduncle articles 4–5 with about 10 and 14 ventral tufts of long, simple densely set, somewhat curling setae; article 5 length about 0.9 of article 4; flagellum articles 1 and 2 with several slender robust setae.

Mouthparts, mandible palp article 1 with 2 medial, 3 ventral and 4 apical long setae; vestigial article 2 at center of article 1 apex.

Gnathopod 1 propodus length 3.0 width, with 2 mid-posterior robust setae. Gnathopod 2 propodus length 2.0 greatest width. Pereopods 3–4 basis with scattered long and short setae along anterior margin, row of long setae in distal half of posterior margin; merus with single mid-anterior and anterodistal group of long setae, with row of medium length setae along distal half of posterior margin. Pereopods 5–6 basis anterior margin with row of long setae in distal half, posterior margin with single short seta in distal half.

Uropod 1 peduncle dorsolaterally with row of 2–3 robust setae, tuft of curved setae distally, ventral apical margin with corona of strong denticles; outer ramus approximately 0.6 length of peduncle, lateral margin with 3–4 robust setae, single simple seta mid-dorsally; inner ramus 0.8 length of outer ramus, straight. Uropod 2 peduncle approximately half length of peduncle of uropod 1, with finely fimbriate corona, reaching to uropod 3 ramus; ramus 0.3 length of peduncle, almost entirely reaching beyond uropod 3 ramus. Uropod 3 peduncle with rounded median projection carrying a few simple setae apically; ramus with 2–3 long simple setae. Telson width approximately 1.2 length, apex nearly straight.

Female. Much less setose than male, especially antennae. Uropods 1 with more robust setae on peduncle and outer ramus. Sternal papillae about twice as long as wide at base, forward curved with blunt apex.

Size. Largest ♂, 3.0 mm; largest ♀, 3.0 mm.

Colour and biology. No observations.

Distribution. Western Australia, Ningaloo at Cape Range, 2 m.

Remarks. Rhinoecetes setosus sp. nov. shares with R. caetus sp. nov. (above) 2–3 robust setae on uropod 1 peduncle and a distoventral corona with small denticles. It differs from R. caetus by its straight rather than curved rostrum, the longer uropod 2 ramus reaching beyond uropod 3 ramus, and the much more setose male antenna 2.

Figures

FIGURE 17. Rhinoecetes setosus sp. nov. Holotype, ♂, except F, paratype, ♀. a2 flag, antenna 2 flagellum; cdv, cephalon dorsal view; clv, cephalon lateral view; md plp, mandible palp; vp, antenna 2 article 2 ventral projection. Scale for habitus and F: 1 mm.

FIGURE 18. Rhinoecetes setosus sp. nov. Holotype, ♂, except F, paratype, ♀. gp1, gnathopod 1; gp2, gnathopod 2; p4, pereopod 4; p6, pereopod 6; sp, sternal papilla (left lateral view); 6 and 7, pereonites 6 and 7; us, urosome, with uropod 1 and 2 peduncle distal ventral margin enlarged.