Rhinoecetes anneae, Just, Jean, 2012

Just, Jean, 2012, Siphonoecetini Just, 1983 (Crustacea, Amphipoda, Ischyroceridae) 10: Belkginoecetes gen. nov., Tropicoecetes gen. nov. and Rhinoecetes Just, 1983 from north-eastern and northern Australian shallow water, with eight new species, Zootaxa 3528, pp. 1-28 : 24-26

Rhinoecetes anneae sp. nov.

Figures 16–18

Type fixation. Holotype, male, here designated.

Etymology. This species is named for my wife Anne Auzimour Just who stood crocodile-watch while I collected in the murky water south of Gunn Point.

Material examined. Holotype, 3, 4.0 mm, tip of East Point north side, Darwin Harbour, Northern Territory, Australia, 12°34’S, 130°34’E, intertidal at LW, medium grained rippled mineral sand between rocks, a few millimetres of water at bottom of ripples with shell fragments and some detritus, hand, J. Just, 19 August, 1984, stn AU 43, MAGNT Cr004035.

Paratypes. Same data as holotype, MAGNT Cr004036 (10 specimens, mostly 3, 14 occupied abodes). Same data as holotype, MAGNT Cr004037 (3B, Fig. 18 B). Same data as holotype, MAGNT Cr004038 (40 specimens, 3, Ƥ, young, 10 occupied abodes). Tip of East Point south side, Darwin Harbour, Northern Territory, Australia, 12°34’S, 130°34’E, 1.5m (LW), fine mineral sand with some detritus, hand dredge, J. Just, 26 August 1984, stn AU 46, MAGNT Cr004039 (1 3, 16 abodes, 12 occupied, 4 commensal Copepoda). Tip of East Point south side, Darwin Harbour, Northern Territory, Australia, 12°34’S, 130°34’E, 1.75m (LW), fine rippled mineral sand with fine shell fragments and detritus, hand dredge, J. Just, 26 August 1984, stn AU 47, MAGNT Cr004040 (1 3, 10 abodes, 7 occupied, 5 commensal Copepoda). Tip of East Point south side, Darwin Harbour, Northern Territory, Australia, 12°34’S, 130°34’E, 2 m (LW), fine mineral sand, shell fragments, some mud and detritus, hand dredge, J. Just, 26 August 1984, stn AU 48, MAGNT Cr004041 (1 young, 14 abodes, 3 occupied). Between Gunn Point and Tree Point, Darwin Harbour, Northern Territory, Australia, 12°11’S, 131°00’E, intertidal (LW), fine dark rippled mineral sand with some detritus, hand, J. Just, 28 August 1984, stn AU 49, MAGNT Cr004042 (1 Ƥ with fully developed oostegites, 3.6 mm, 8 abodes, 4 occupied). Tip of East Point north side, Darwin Harbour, Northern Territory, Australia, 12°34’S, 130°34’E, intertidal at LW, medium grained rippled mineral sand between rocks, a few millimetres of water at bottom of ripples with shell fragments and some detritus, hand, J. Just, 19 August, 1984, stn AU 43, ZMUC-CRU-20521 (5 specimens, 4 occupied abodes).

Description (holotype, 3). Head as long as pereonites 1 and half of 2 combined along dorsal midline; midanterior 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 its length. Eye lobes rounded in lateral view with nearly parallel dorsal and ventral margins, lower distal margin with single simple setae.

Antenna 1 approximately as long as head, pereonites 1–5 and 2/3 of 6 combined, reaching to proximal 1/3 of antenna 2 peduncle article 5; flagellum of 6+ articles, as long as peduncle articles 1 and 2 combined. Antenna 2 approximately as long as head, pereonites 1–7 and pleonites 1 and 2 combined; ventral projection of peduncle article 2 as long as broad at base, broadly rounded, with fringe of long simple setae apically and laterally; articles 3–5 with dorsal, ventral and lateral groups of long simple setae, longest and densest on article 5; article 5 length 0.85 of article 4; flagellum articles 1 and 2 with slender robust setae.

Mouthparts, mandible palp article 1 with 1 medial, 4 ventral and 4 apical long setae.

Gnathopod 1 propodus length 4.0 width, with 3 midposterior robust setae. Gnathopod 2 propodus length 1.9 greatest width. Pereopods 3–4 basis with broken row of long setae on anterior margin, single long seta on lateral surface, group of unequally long setae in distal half of posterior margin; merus with midanterior and anterodistal groups of long setae, posterior margin with a few groups of unequally long setae in distal half and crescent of long setae apically. Pereopods 5–6 basis anterior margin with group of a few long setae in distal half and crescent of long setae in distal corner, posterior margin with scattered unequally long setae.

Uropod 1 peduncle with 1 or 2 dorsolateral small simple setae, ventral apical margin with crescent of strong denticles ( Fig. 16 up1 vv); outer ramus slightly inward curved, approximately 0.5 length of peduncle, lateral margin with 2 robust setae; inner ramus 0.65 length of outer ramus, straight. Uropod 2 peduncle approximately half length peduncle of uropod 1; ramus half length of peduncle, reaching beyond uropod 3 ramus with about 1/4 its length. Uropod 3 peduncle with rounded median projection carrying 2 simple setae apically; ramus with 3 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. 17 Fsp). Size. Largest 3, 4.0 mm; largest Ƥ, 3.6 mm.

Colour and biology. Body pale amber transparent mottled with white pigment shining through; anterior 1/3 of head and rostrum light sandy coloured. Coxal plates and pereopods colourless transparent. Antenna 1 peduncle article 1 with orange-red blotch at base; articles 2–3 and flagellum colourless except for continuous central red-brown string. Antenna 2 generally faintly milky transparent, except for peduncle articles 4 and 5 with red-brown ring at base

Specimens occupy a range of suitable abodes, most commonly microprosobranch shells and some bivalves, polychaete tubes and scaphopods. Abode aggregates observed including 1 3 and 2 Ƥ ( Fig. 18 A).

Distribution. Australia, Northern Territory, Darwin Harbour, intertidal sand ripples at LW to 2 m at LW. (Note that the tidal amplitude in the area is approximately 4.5–7.5 m, the low water amplitude 0 to about 4.5 m).

Figures

FIGURE 16. Rhinoecetes anneae gen. et sp. nov. Holotype, 3, except F, paratype Ƥ. a 2 flag, antenna 2 flagellum; c dv and c lv, head dorsal and lateral view; up 1 vv, uropod 1 ventral view; us, urosome. Habitus scale: 1 mm.

FIGURE 17. Rhinoecetes anneae gen. et sp. nov. Holotype 3, except F, paratype Ƥ. gp 1 and gp 2, gnathopods 1 and 2; md plp, mandible palp; p 3 and p 5, pereopods 3 and 5; sp, sternal papillae (6 and 7, pereonites 6 and 7); vp, ventral projection of article 2 of antenna 2.

FIGURE 18. Rhinoecetes anneae gen. et sp. nov. A, abode aggregate of paratype male in scaphopod and 2 paratype females in microprosobrancs, (type locality). B, paratype, 3 B, (type locality).