Rhinoecetes sinuduopopulus, 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 : 105-108

Rhinoecetes sinuduopopulus sp. nov.

Figures 3–4

Type fixation. Holotype, male, here designated.

Etymology. The epithet is a latinisation of the type locality Two (duo) Peoples (populus) Bay (sinus).

Material examined. Holotype, ♂, 4.1 mm. Two Peoples Bay, east of Albany , Western Australia, south-western corner, 34°58.20’S 118°11’E, 1 m, sand, shell and foraminiferan debris, detritus, just inside dense sea-grass belt, hand dredge, J. Just, 30 March 1984, stn AU27, WAM C73430.

Paratypes. Same data as holotype, WAM C73431 (about 100 abodes and many free specimens) . Same data as holotype, WAM C73432 (4 specimens) . Two Peoples Bay, east of Albany , Western Australia, south-western corner, 34°58’S 118°11’E, 1 m, sand with detritus just inside dense sea-grass belt, hand dredge, J. Just, 28 March 1984, stn AU24, WAM C73433 (1 specimen) . Same data as holotype, NHMD-233132 (10 specimens) .

Description (♂). Head as long as pereonites 1 and 2 combined along dorsal midline; mid-anterior depression moderately deep, encompassing approximately 0.3 head length. Rostrum straight, acutely pointed, in dorsal view reaching beyond apices of eye lobes with about half length. Eye lobes in lateral view tapering to blunt apex, lower distal margin with 1–2 short simple setae.

Antenna 1 approximately as long as head and pereonites 1–3.5 combined, reaching 4/5 along antenna 2 peduncle article 4; flagellum of 5+ articles, as long as peduncle articles 2 and 4/5 of 3 combined, peduncle article 1 medial margin with proximal bulge. Antenna 2 approximately as long as head, pereonites 1–7 and urosomite 1 combined; ventral projection of peduncle article 2 slightly longer than broad at base, triangular, tapering to rounded apex, with short fringe of simple setae apically and laterally; peduncle articles 4–5 with dorsal, ventral and lateral groups of simple setae, longest and densest in groups on article 5; article 5 length 4/5 of article 4; flagellum articles 1 and 2 with many slender robust setae.

Mouthparts: mandible palp article 1 with about 8 long setae, vestigial article 2 situated on corner of article 1 apex.

Gnathopod 1 propodus length 2.9 width, with 3 mid-posterior robust setae. Gnathopod 2 propodus length 1.7 greatest width. Pereopods 3–4 basis with long and short setae along anterior margin, merus with mid-anterior and anterodistal long setae, posterior margin with 4–5 groups of unequally long setae. Pereopods 5–6 basis anterior margin with several long setae in distal half, posterior margin with a few setae.

Uropod 1 peduncle with a couple of simple setae dorsolaterally, and tuft of longer simple setae distally, ventral apical margin with corona of strong denticles; outer ramus slightly inwardly curved, approximately 0.6 length of peduncle, dorsolaterally with 3 robust setae; inner ramus 0.8 length of outer ramus, straight. Uropod 2 peduncle approximately half length of peduncle of uropod 1, with finely fimbriate corona; ramus 0.6 length of peduncle, 0.5–0.54 length of uropod 1 inner ramus, reaching beyond uropod 3 ramus with about 1/5 its length. Uropod 3 peduncle with rounded median projection carrying a few simple setae apically; ramus with 3–4 long simple setae. Telson width approximately 1.2 length, apex straight.

Female. Generally as male, except uropod 1 outer ramus with up to 5 robust setae. Pereonite 7 ventrally with short, broadly rounded sternal papillae ( Fig. 4 Fsp).

Size. Largest ♂, 4.1 mm; largest ♀, 3.8 mm.

Colour. Head and body covered with whitish pigment over brownish entrails. Antenna 1 peduncle article 1 with red brown patch at base, peduncle otherwise with some white patches. Antenna 2 peduncle article 3 white, article 4 with broad white rings proximately and distally. Flagella colourless semitransparent. Abodes. The many abodes from stn 27 are all micromollusc shells.

Distribution. Western Australia, Two Peoples Bay, east of Albany, 1 m.

Remarks. See Rhinoecetes makritrichoma sp. nov. below for comparison with that and similar species.

Figures

FIGURE 3. Rhinoecetes sinuduopopulus. sp. nov. Holotype, ♂, except F, paratype, ♀. a2 flag, antenna 2 flagellum; cdv, cephalon dorsal view; clv, cephalon lateral view; md plp, mandible palp; vp, ventral projection of article 2 of antenna 2. Scale for habitus and F: 1 mm.

FIGURE 4. Rhinoecetes sinuduopopulus 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; up 1 and 2, uropod 1 and 2 peduncle ventral apical margin; us, urosome.