Rhinoecetes rockinghamia, 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 : 108-111

Rhinoecetes rockinghamia sp. nov.

Figures 5–6

Type fixation. Holotype, ♂, here designated.

Etymology. The species is named for the township of Rockingham south of Perth.

Material examined. Holotype, ♂, 3.9 mm. North side of Point John, Rockingham , Western Australia, 32°15.53’S 115°41.10’E, 1.5 m, coarse sand with some detritus immediately outside dense belt of Amphibolis sea grass and algae, hand dredge, J. Just, 8 March 1984. stn AU 5, WAM C73434.

Paratypes. Same sample as holotype, WAM C73435 (♀ A, 3.7 mm, 8 ♀♀). Same sample as holotype, WAM C73436 (ca. 100 abodes). Same sample as holotype, WAM C73437 (ca. 100 free specimens). Same sample as holotype, WAM C73438 (abode aggregates). North side of Point John , Rockingham , Western Australia, 32°15.55’S 115°41.15’E, 2.0 m, coarse sand outside sea grass belt, hand dredge, J. Just, 12 March 1984, stn AU9, WAM C73439 (2 specimens). North side of Point John , Rockingham , Western Australia, 32°15.54’S 115°41.12’E, 2.0 m, coarse sand just outside dense sea grass belt, hand dredge, J. Just, 6 April 1984, stn AU29, WAM C73440 (a few abodes and specimens). Same sample as holotype, NHMD-233133 (8 specimens). Reef west of Groyne , 2 km south of Cape Peron , Western Australia, 32°16’S 115°41’E, 6 m, sand pockets, JK Lowry, 26 Dec. 1983, stn WA- 292, AM P35071 (ca. 100 specimens). Reef west of Groyne , 2 km south of Cape Peron , Western Australia, 32°16’S 115°41’E, 6 m, Caulerpa , JK Lowry, 26 Dec. 1983, stn WA-302, AM P35072 (1 specimen with abode) .

Description (♂). 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 with about half length. Eye lobes broadly rounded in lateral view, lower distal margin with 1–2 simple setae.

Antenna 1 approximately as long as head and pereonites 1–4 combined, reaching to proximal 1/4 of antenna 2 peduncle article 5; flagellum of 5+ articles, as long as peduncle articles 2 and 3 combined, peduncle article 1 medial margin with proximal bulge. Antenna 2 approximately as long as head and pereonites 1–6 and half of 7 combined; ventral projection of peduncle article 2 approximately as long as broad at base ( Fig. 5 vp, in slightly oblique view), tapering to rounded apex, with short fringe of long simple setae apically and laterally; peduncle articles 4–5 with dorsal, ventral and lateral groups of simple setae, longest and densest on article 5; article 5 length 0.9 of article 4; flagellum articles 1 and 2 with many slender robust setae.

Mouthparts, mandible palp article 1 with 4 lateral, 4 medial and 3 or 4 apical long setae.

Gnathopod 1 propodus length 3.2 width, with 3 mid-posterior robust setae. Gnathopod 2 propodus length 2.0 greatest width. Pereopods 3–4 basis with sequentially long and short setae along anterior margin, group of long setae submarginally in distal half of posterior 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 2 submarginal, transverse rows of long setae in distal half, posterior margin with a few short setae.

Uropod 1 peduncle dorsolaterally with row of 5–7 robust setae, 1 simple seta proximally, and tuft of long setae distally, ventral apical margin with corona of strong denticles; outer ramus slightly inwardly curved, approximately 0.45 dorsal length of peduncle, lateral margin with 3–4 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 0.4 length of peduncle, 0.5 length of uropod 1 inner ramus, reaching just beyond uropod 3 ramus. Uropod 3 peduncle with rounded median projection carrying a few simple setae apically; ramus with 2 long simple setae. Telson width approximately 1.4 length, apex evenly convex.

Female. Generally as male. Pereonite 7 ventrally with short, forward curving sternal papillae ( Fig. 6 Fsp).

Size. Largest ♂, 3.9 mm; largest ♀, 3.7 mm.

Colour. Antenna 1 transparent colourless, except articles with fine white or reddish rings apically; peduncle article 1 red brown at base; antenna 2 and entire body white, entrails faintly shining through in yellowish-brown; mandible palp brown; all other appendages mostly transparent colourless; eyes white with black ocelli. Abodes. The numerous abodes from the type locality were all microprosobranch shells. A few abode aggregates was observed.

Distribution. Western Australia, Rockingham, 1– 2 m.

Remarks. Rhinoecetes rockinghamia sp. nov. shares with R. lowryi sp. nov. (below) the long row of 5–7 robust setae on the peduncle of uropod 1. It differs from R. lowryi by its broadly rounded eye lobes in lateral view (elongate, apically truncate), and in the strongly denticulate uropod 1 peduncular corona (finely fimbriate).

Figures

FIGURE 5. Rhinoecetes rockinghamia sp. nov. Holotype, ♂, except F, ♀ paratype. a2 flag, antenna 2 flagellum; cdv, cephalon dorsal view; clv, cephalon lateral view; vp, ventral projection of article 2 of antenna 2. Scale for habitus and F: 1 mm.

FIGURE 6. Rhinoecetes rockinghamia sp. nov. Holotype, ♂, except F, ♀ paratype. gp1, gnathopod 1; gp2, gnathopod 2; md plp, mandible palp; p4, pereopod 4; p6, pereopod 6; up ped vv, uropods 1 and 2 peduncles, ventral apical margin; us, urosome; sp, sternal papilla (left lateral view).