Rhinoecetes brevirostris, Just, Jean, 2012

Just, Jean, 2012, Siphonoecetini Just, 1983 (Crustacea, Amphipoda, Ischyroceridae) 9: New species in Rhinoecetes Just, 1983, Cephaloecetes gen. nov. and Neoecetes gen. nov. from the south-eastern Australian shelf, Zootaxa 3234, pp. 1-42 : 17-20

Rhinoecetes brevirostris sp. nov.

Figures 11 , 12

Type fixation. Holotype, male, here designated.

Etymology. The species is named for its short (Latin brevis), broad, triangular rostrum.

Material examined. Holotype. 3, 5.3 mm, New South Wales, 1.5 km E of Burwood Beach, 33°02’36”S, 151°40’56”E, 12 m, Australian Museum Hunter District Water Board Survey, 18 March 1975, AM P23092. Paratypes. New South Wales, Sydney: S end of Manly, 33°48’S, 151°17’E, 9 m, dredge, Australian Museum Party, 30 June 1971, AM P18279 (5 ovigerous Ƥ, 2 3, 1 young). Off Manly Beach, 33°48’S, 151°18’E, 6 m, sandy clean bottom, trawl, P.A. Hutchings, 30 June 1971, AM P18287 (33, 2 Ƥ). 500 m E of Burwood Beach, 32°57’31”S, 151°44’43”E, 16 m, coarse sand, Australian Museum Hunter District Water Board Survey, stn HDWBS 06020103, 31 October 1975, AM P23080 (ca. 60 specimens). 500 m E of Burwood Beach, 32°57’31”S, 151°44’43”E, 16 m, coarse sand, Australian Museum Hunter District Water Board Survey, stn HDWBS 06020103, 31 October 1975, AM P87046 (ƤA, ovigerous, 4.5 mm, illustrated). 500 m E of Burwood Beach, 32°57’31”S, 151°44’43”E, 14 m, coarse sand, Australian Museum Hunter District Water Board Survey, stn HDWBS 06030104, 18 December 1975, AM P23081 (35 specimens). 500 m E of Belmont Beach, 33°02’36”S, 151°40’56”E, 12 m, Australian Museum Hunter District Water Board Survey, stn HDWBS 09020103, 22 August 1975, AM P23093 (13, 1 ovigerous Ƥ). 500 m E of Stocton Beach, 32°53’55”S, 151°47’31”E, 10 m, Australian Museum Hunter District Water Board Survey, stn HDWBS 15010102, 20 July 1975, AM P23100 (1 ovigerous Ƥ). Jervis Bay, 35°05’S, 150°73’E, T. Whitelegge, AM P84640.

Victoria: Portland, Grant Bay, 9 m, sandy bottom, 3 March 1981, NMV J62532 (many young, a few adults, 2 specimens in prosobranch abodes).

Tasmania: off Hellfire Bluff, S of Cape Bernier, 12 m, sandy bottom, van Veen grab, A.J. Dartnall, 7 June 1977, TMAG (1 specimen).

Other material. New South Wales, Eden, Legger Beach, Quarantine Bay, 37°04’S, 149°55’E, 2 m, pipe dredge, S. Keable and P. Albertson, 22 February 1985, AM P36303 (2 3).

Description (holotype, 3). Head barely longer than pereonite 1, midanterior depression moderately deep, encompassing approximately 0.6 head length. Rostrum short, straight, in dorsal view triangular, as long as broad at base, reaching beyond apices of eye lobes with about one third its length, acutely pointed. Eye lobes rounded in lateral view, lower anterior margin with a single simple seta. Head and pereon with small poly-flagellate setae, on pereonites in 2 transverse rows.

Antenna 1 approximately as long as head and pereonites 1–5 combined, reaching slightly beyond apex of antenna 2 peduncle article 4; peduncle articles 1 and 2 with dense bunches of long setae ventrally; flagellum of 7+ articles, approximately as long as peduncle. Antenna 2 as long as entire body from head to telson apex; ventral projection of peduncle article 2 length about 1.6 width at base, with lateral and apical row of long setae, apex rounded; article 4 and 5 with densely set bunches of long simple setae; article 5 length 0.9 of 4; flagellum articles 1 and 2 with many long, slender robust setae.

Gnathopod 1 propodus length 2.8 width, with 4 midposterior robust setae. Gnathopod 2 propodus length 1.75 greatest width. Pereopods 3–4 basis with open row of setae on anterior and posterior margins, distolateral surface with a single seta; merus with anterior and posterior groups of unequally long setae. Pereopods 5–6 basis anterior margin with 1 distal and 1 apical tufts of long setae, posterior margin with a few unequally long setae. Pereopod 7 propodus anterior margin with 5 groups of long setae.

Uropod 1 peduncle with dorsolateral row of simple setae only, distomedial corner with single simple seta; outer ramus straight, 0.6 length of peduncle, lateral margin with a few robust setae, medial margin and dorsal surface smooth; inner ramus 0.75 length of outer ramus, slender, straight, smooth. Uropod 2 not reaching apex of peduncle of uropod 1, peduncle 0.4 length of peduncle uropod 1, ramus about half length of peduncle, overreaching ramus uropod 3 with nearly its entire length. Uropod 3 peduncle with rounded median projection carrying a few small simple setae; ramus with crescent of 5–6 long setae. Telson width approximately 1.8 length, distal margin broadly rounded,

Female. Similar to male. Mouthparts, mandible palp article 1with 3 dorsal and 4 ventral long setae, apex with group of long setae. Sternal papillae are on the anterior half of pereonite 7; they are nearly straight, forward pointing at 45°, slightly swollen mid length (possibly an artefact); internal tissue is visible.

Size. Largest 3, 5.3 mm; largest Ƥ, 6.0 mm.

Variation. In some specimens the rostrum is shorter and more wide angled than in the holotype, in some slightly more pointed. Two specimens from southern New South Wales (AM P36303) have an especially long rostrum, though still triangular and broad at base; those 2 specimens are not included in the paratype series.

Colour and biology. Colour not known. A few specimens were found in micro prosobrancs and broken polychaete tubes.

Distribution. Eastern Australia from Sydney south to western Victoria and eastern Tasmania, 6– 16 m.

Figures

FIGURE 11. Rhinoecetes brevirostris sp. nov. Holotype, 3. a 2 flag, antenna 2 flagellum; c, head (dv, dorsal view, lv, lateral view); us, urosome with uropods; vp, ventral projection of antenna 2 article 2. Habitus scale: 1 mm.

FIGURE 12. Rhinoecetes brevirostris sp. nov. Holotype, 3, except F, paratype, ƤA, ovigerous, and F 1, paratype, ovigerous Ƥ. gp 1 – 2, gnathopods 1 and 2; md, mandible; p 4 – 5, pereopods 4 and 5. 6, 7, pereonites 6 and 7. Habitus scale: 1 mm.