Pararhinoecetes bicornis, 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 : 135-137

Pararhinoecetes bicornis sp. nov.

Figures 23–24

Type fixation. Holotype, ♂, here designated.

Etymology. The epithet refers to the rostrum being split into two acute points.

Material examined. Holotype, ♂, 5.0 mm. Western Australia, North West Shelf , 19°29.6’S 118°52.2’E to 19°29.4’S 118°52.8’E, 38 m, sled, CSIRO 04 -B8-S, stn W224, 30 Aug. 1983, AM P38885.

Paratypes. Same sample as holotype, AM P 101866 (7 specimens) . Western Australia, North West Shelf , 19°27'11"S, 118°58' 36"E, 36–46 m, epibenthic sled, CSIRO 06 -B9-S, stn W281, WAM C73462 (15 specimens) . Western Australia, North West Shelf , 19°27'11"S, 118°58' 36"E, 36–46 m, epibenthic sled, CSIRO 06 -B9-S, stn W281, AM P 101867 (5 specimens) . Western Australia, North West Shelf , 19°27'11"S, 118°58' 36"E, 36–46 m, epibenthic sled, CSIRO 06 -B9-S, stn W281, NHMD-233162 (5 specimens) .

Description (holotype, ♂). Head without mid-anterior depression, as long as pereonites 1 and half of 2 combined along dorsal midline. Rostrum split into two small, short acute points separated by round-bottomed incision. Eye lobes tapering to rounded apex in lateral view, lower distal margin with up to 3 simple setae.

Antenna 1 approximately as long as head and pereonites 1–7 combined, peduncle article 1 slightly shorter (0.9) than 2, in dorsal view with 2–3 lateral and medial setiferous projections; flagellum of 6+ articles, as long as peduncle articles 2 and 3 combined. Antenna 2 beyond article 3 not known; ventral projection of peduncle article 2 approximately 0.6 as long as wide at base (one corner could not be viewed), with about 8 long simple setae along lateral and apical margin.

Mouthparts: mandible palp article 1 with 8–9 medial and lateral, and 4 terminal long setae.

Gnathopod 1 propodus length 3.3 width, with 4 mid-posterior robust setae. Gnathopod 2 propodus length 1.8 greatest width. Pereopods 3–4 basis with long and short setae along anterior margin; merus with 2 mid-anterior and anterodistal group of long setae, posterior margin with 4–5 groups of unequally long setae. Pereopods 5–6 basis with a few long and short setae along distal half of anterior margin, group of moderately long setae in proximal half of posterior margin.

Uropod 1 peduncle dorsolaterally with short row of small simple setae, tuft of curved setae distolaterally, distomedial corner with single robust seta; ventral apical margin with finely fimbriate corona; outer ramus slender, elongate, slightly inwardly curved, approximately 0.65 dorsal length of peduncle, lateral margin with 5 slender robust setae, dorsal surface with 3 small simple setae; inner ramus 0.6 length of outer ramus, slender, slightly inwardly curved. Uropod 2 peduncle approximately 0.4 length of peduncle of uropod 1, dorsally with 3 simple setae, corona finely fimbriate, reaching to or just beyond uropod 3 ramus; ramus 0.7 length of peduncle, 0.8 length of uropod 1 inner ramus, slender, similar to inner ramus of uropod 1. Uropod 3 peduncle with rounded median projection carrying a few simple setae apically; ramus with bunch of 5–6 long simple setae. Telson width approximately 1.2 length, apex straight to slightly concave.

Female. Generally as male. Uropod 1 peduncle with a couple more setae. Pereonite 7 ventrally with elongate forward pointing sternal papillae.

Size. Largest ♂, 5.0 mm; largest ♀, 5.9 mm.

Colour and biology. No observation.

Distribution. Northwest Shelf, Western Australia, 38– 48 m.

Figures

FIGURE 23. Pararhinoecetes bicornis gen. et sp. nov. Holotype, ♂, except F, paratype, ♀. cdv, cephalon dorsal view; clv, cephalon lateral view; md plp, mandible palp; mx1 plp, maxilla 1 palp; us, urosome; 1 and 2, uropods 1 and 2 ventral apical margin; vp, ventral projection of article 2 of antenna 2. Habitus scale: 1 mm.

FIGURE 24. Pararhinoecetes bicornis gen. et sp. nov. Holotype, ♂. gp1 and gp2, gnathopods 1 and 2; p4 and p5, pereopods 4 and 5; sp, sternal papilla (left lateral view), 6 and 7, pereonites 6 and 7.