Hippomedon geelongi Stebbing, 1888

Kilgallen, N. M. & Lowry, J. K., 2015, The genus Hippomedon in Australian waters (Crustacea, Amphipoda, Lysianassidae, Tryphosinae), Zootaxa 3926 (3), pp. 377-395 : 378-382

Hippomedon geelongi Stebbing, 1888

( Figs 1–4 )

Hippomedon geelongi Stebbing, 1888: 635 , pl. XI.— Stebbing, 1906: 61.— Sheard, 1937: 19 (catalogue).— P.G. Moore, 1989: 1459 (key).—Lowry & Stoddart, 12003: 166 (catalogue).

Types. Holotype, male, ~ 12.7 mm, NHM 1889.5.15.12.

Type locality. Off the entrance to Port Phillip Bay, Victoria (38°22.5'S 144°36.5'E), 60 m, trawl, sand, 1 April 1874, HMS Challenger [stn 161].

Material examined. New South Wales. 2 specimens, AM P.69731, east of Long Reef (33°43'S 151°46'E), 174 m, epibenthic sled, 20 December 1985, J.K. Lowry & R.T. Springthorpe, FRV Kapala [K 85-21-08]; 1 specimen, AM P.22027, 28 km east of Malabar, Sydney (33°58.9'S 151°33.63'E), 187 m, 9 August 1973, Australian Museum Shelf Benthic Survey [Stn 44]; 3 specimens, AM P.47035, off Wollongong (34°32.08'S 151°12.55'E), 200 m, baited trap, 7–8 May 1993, P. Freewater & S.J. Keable & W. Vader, MV Robin E [NSW-797].

Tasmania. 1 female, AM P.69734; 5 specimens, AM P.69733, east of Fortescue Bay, north of Hippolyte Rocks, (43°06.7'S 148°03.46'E), 100 m, baited trap, 8–9 April 1994, J.K. Lowry & K. Dempsey, MV Martrudan [TAS- 390]; 1 male, AM P.69736; 21 specimens, AM P.69735, east of Fortescue Bay, north of Hippolyte Rocks, (43°06.7'S 148°03.46'E), 100 m, baited trap, 8–9 April 1994, J.K. Lowry & K. Dempsey, MV Martrudan [TAS- 391]; 1 specimen, AM P.69732, mouth of Fortescue Bay, (43°07.76'S 147°59.46'E), 50 m, baited trap, 8–9 April 1994, J.K. Lowry & K. Dempsey, MV Martrudan [TAS-387]; 1 male, NMV J67811 , western Bass Strait, King Island, 54 km west of Stokes Point (40°06'S 143°17'E), 158 m, medium sand, Smith-McIntyre grab, 11 October 1980, G.C.B. Poore, HMAS Kimbla [BSS-100G]; 1 specimen, NMV J67812 , central Bass Strait, Three Hummock Island, 47 km east of Cape Rochon (40°23.8'S 145°32'E), 65 m, muddy sand, epibenthic sled, 3 November 1980, M. Gomon & G.C.B. Poore [BSS-113S]; 1 specimen, NMVJ 67813, central Bass Strait, 100 km south-south-east of Cape Liptrap (39°45.9'S 145°33.5'E), 74 m, muddy fine sand, epibenthic sled, 13 November 1981, R. Wilson, RV Tangaroa [BSS-156S]; 1 specimen, NMV J67814 , central Bass Strait, 38 km south-west of Cape Paterson (38°55.5'S 145°17.0'E), 70 m, fine sand, epibenthic sled, 12 November 1981, R. Wilson, RV Tangaroa [BSS- 155G]; 4 specimens, AM P.45745, mouth of Fortescue Bay (43°07.76'S 147°59.46'E), 50 m, baited trap, 16–17 April 1993, J.K. Lowry & P. Freewater, MV Tasmanian Enterprise [TAS-350]; 2 specimens, AM P.45778, east of Fortescue Bay, north of Hippolyte Rocks (43°06.7'S 148°03.45'E), 100 m, baited trap, 16–17 April 1993, J.K. Lowry & P. Freewater, MV Tasmanian Enterprise [TAS-353]; 9 specimens, AM P.50824, east of Fortescue Bay, north of Hippolyte Rocks (43°06.7'S 148°03.45'E), 100 m, baited trap, 16–17 April 1993, J.K. Lowry & P. Freewater, MV Tasmanian Enterprise [TAS-354]; 1 specimen, AM P.50895, east of Fortescue Bay, north of Hippolyte Rocks (43°06.7'S 148°03.45'E), 100 m, baited trap, 8–9 April 1994, J.K. Lowry & K. Dempsey, MV Martrudan [TAS-390]; 10 specimens, AM P.50925, mouth of Fortescue Bay (43°07.76'S 147°59.46'E), 50 m, baited trap, 9–10 April 1994, J.K. Lowry & K. Dempsey, MV Martrudan [TAS-406]; 7 specimens, AM P.51320, east of Fortescue Bay, north of Hippolyte Rocks (43°06.7'S 148°03.45'E), 100 m, baited trap, 9–10 April 1994, J.K. Lowry & K. Dempsey, MV Martrudan [TAS-409]; 177 specimens, AM P.51331, east of Fortescue Bay, north of Hippolyte Rocks (43°06.7'S 148°03.45'E), 100 m, baited trap, 9–10 April 1994, J.K. Lowry & K. Dempsey, MV Martrudan [TAS-408]; 4 specimens, AM P.58245, east of Fortescue Bay, north of Hippolyte Rocks (43°06.7'S 148°03.45'E), 100 m, baited trap, 8–9 April 1994, J.K. Lowry & K. Dempsey, MV Martrudan [TAS-389].

Description. Based on female, 15.1 mm, AM P.69734.

Head lateral cephalic lobes subtriangular, apically subacute. Antenna 1 peduncular article 1 without anterodistal lobe; article 2 without anterodistal lobe; accessory flagellum present, not forming cap, 5-articulate, terminal article not offset; flagellum with strong 2-field callynophore; calceoli absent. Antenna 2 peduncular article 3 short; articles 3–5 not enlarged; flagellum short, calceoli absent. Labrum (epistome and upper lip) separate; epistome produced equally with upper lip, straight; upper lip not produced. Mandible molar columnar, with oval fully triturating surface; palp attached extremely distally. Maxilla 1 inner plate with 1 large apical pappose seta and 5 smaller pappose setae along inner margin; outer plate setal-tooth 7 present, cuspidate distally along inner margin; palp distal margin with apical robust setae. Maxilliped outer plate with one slender and one broad, long, apical robust setae.

Gnathopod 1 subchelate; coxa large, about as long as coxa 2, subrectangular with straight anterior margin; basis moderately setose along anterior margin; ischium short; carpus long, subequal in length to propodus, without posterior lobe; propodus small, margins weakly diverging distally, sparsely setose along posterior margin, palm slightly acute, entire, convex. Gnathopod 2 propodus palm transverse to slightly acute, straight. Pereopod 4 coxa posteroventral lobe moderately developed. Pereopod 5 coxa without distinct lateral ridge, basis about as long as broad, not posteroproximally excavate, posterior margin weakly serrate, posterior margin without mid-central spine, without posteroventral lobe or spine. Pereopod 7 basis posterodistally produced less than halfway along merus, not posterodistally excavate.

Epimeron 2 posteroventral corner producing small spine. Epimeron 3 posterior margin smooth, posteroventral corner forming a broad upwardly curved spine. Urosomite 1 projecting over urosomite 2, dorsodistally acute. Uropod 2 rami subequal in length, inner ramus without constriction. Uropod 3 stout; peduncle without dorsolateral flange; inner and outer rami well developed, outer ramus article 2 short, with plumose setae on both rami. Telson deeply cleft, with 2 dorsal and 1 apical robust setae on each lobe.

Sexually dimorphic characters. Based on male, 14.9 mm, AM P.69736. Antenna 1 flagellum with strong 2- field callynophore; calceoli present, small. Antenna 2 calceoli present.

Depth range. 50– 200 m.

Remarks. Until now, this species was only known from the unique holotype taken off the entrance to Port Phillip Bay, Victoria. We extend the distribution of H. geelongi from Victoria southwards into Tasmania, and northwards into New South Wales as far as Long Reef.

Distribution. Australia. Eastern and south-eastern coasts from east of Long Reef, New South Wales (33°43'S 151°46'E) to Fortescue Bay, Tasmania (this study), and the entrance to Port Phillip Bay, Victoria ( Stebbing 1888).

Figures

FIGURE 1. Hippomedon geelongi Stebbing, 1888, male, 11.8 mm, NMV J 67811, from 54 km west of Stokes Point, King Island, western Bass Strait.

FIGURE 2. Hippomedon geelongi Stebbing, 1888, female, 15.1 mm, AM P. 69734; male, 14.9 mm, AM P. 69736, both from north of Hippolyte Rocks, Tasmania. Scale bars: antennae, 0.5 mm; remainder, 0.2 mm.

FIGURE 3. Hippomedon geelongi Stebbing, 1888, female, 15.1 mm, AM P. 69734; male, 14.9 mm, AM P. 69736, both from north of Hippolyte Rocks, Tasmania. Scale bars: 0.5 mm.

FIGURE 4. Hippomedon geelongi Stebbing, 1888, female, 15.1 mm, AM P. 69734; male, 14.9 mm, AM P. 69736, both from north of Hippolyte Rocks, Tasmania. Scale bars: 0.5 mm.