Tryphosella fortescue, Lowry & Stoddart, 2011

Lowry, J. K. & Stoddart, H. E., 2011, The tryphosine genera Photosella gen. nov. and Tryphosella Bonnier, 1893 (Crustacea: Amphipoda: Lysianassoidea: Lysianassidae: Tryphosinae) in Australian waters 2956, Zootaxa 2956 (1), pp. 1-76 : 38-42

Tryphosella fortescue sp. nov.

( Figs 24–26 )

Tryphosella sp. 183. — Lowry & Smith, 2003: 56.

Type material. HOLOTYPE, female, ovigerous (6 eggs), 5.4 mm, AM P. 71619, east of Fortescue Bay , north of Hippolyte Rocks, Tasmania, Australia, 43°06.70'S 148°03.45'E, 100 m, baited trap, 9–10 April 1994, J.K. Lowry & K. Dempsey, MV Martrudan, stn TAS-408 . PARATYPES: 1 male, 5.0 mm, AM P.71620; 1 male, 4.4 mm, AM P.71621; 296 specimens, AM P.52145; all with same data as Holotype .

Additional material examined. New South Wales: 10 specimens, AM P.69596, north of Toomeree Head, Port Stephens , 32°42.7'S 152°11.2'E, 15 m, close to rocky shore, baited trap set 1000 –1100 hrs, retrieved 0730–0830 hrs, 1– 2 June 1988, J.K. Lowry & S.J. Keable, stn NSW-304 ; 28 specimens, AM P.47030, off Wollongong, 34°32.09'S 151°12.55'E, 200 m, baited trap, 13.7°C, 7–8 May 1993, P. Freewater, S. Keable & W. Vader, MV Robin E, stn NSW-797 ; 1 specimen, AM P.47014, same data, stn NSW-798 . Tasmania: 1 specimen, MV J11280 , 25 km northeast of Deal Island, eastern Bass Strait , 39°14.8'S 147°31.5'E, 57 m, medium sand, Smith-McIntyre grab, 18 November 1981, RV Tangaroa , stn BSS 174G ; 7 specimens, MV J 62309 , 100 km south-south-east of Cape Liptrap, central Bass Strait, 39°45.9'S 145°33.5'E, 74 m, muddy fine sand, epibenthic sled, 13 November 1981, R. Wilson, RV Tangaroa , stn BSS-156S; many specimens, AM P.69594, about 100 m west of Turners Rock and 80 m offshore, north side of Cape Sorell , 42°11.5'S 145°10.8'E, 13 m, baited trap, probably rocky bottom with sand patches, 27– 28 April 1991, J.K. Lowry & S.J. Keable, stn TAS-301 ; 7 specimens, AM P.69595, 50 m off Weatherhead, Freycinet Peninsula , 42°14'S 148°15'E, 13 m, baited trap, 30 April–1 May 1991, J.K. Lowry & S.J. Keable, stn TAS-339 ; 1 specimen, AM P.45746, mouth of Fortescue Bay, 43°07.77'S 145°59.47'E, 50 m, baited trap, 16.2°C, 16-17 April 1993, J.K. Lowry & P. Freewater, MV Tasmanian Enterprise , stn TAS-350 ; 2 specimens, AM P.52088, same data, 17–18 April 1993, stn TAS-370 ; 3 specimens, AM P.52090, same locality, 16.6°C, 8–9 April 1994, J.K. Lowry & K. Dempsey, MV Martrudan , stn TAS-386 ; 1 specimen, AM P.52091, same data,, stn TAS-387 ; 40 specimens, AM P.52095, same data, 9–10 April 1994, stn TAS-405 ; 1 specimen, AM P.52096, same data, stn TAS-406 ; 24 specimens, AM P.52087 and 3 specimens, AM P.57741, east of Fortescue Bay, north of Hippolyte Rocks, 43°06.70'S 148°03.45'E, 100 m, baited trap, 15.8°C, 16–17 April 1993, J.K. Lowry & P. Freewater, MV Tasmanian Enterprise , stn TAS-354 ; 2 specimens, AM P.52089, same data, 17–18 April 1993, stn TAS-372 ; 23 specimens, AM P.52092, same locality,15.6°C, 8–9 April 1994, J.K. Lowry & K. Dempsey, MV Martrudan , stn TAS-389 ; 24 specimens, AM P.52093 and 1 specimen, AM P.71618, same data, stn TAS-390 ; 110 specimens, AM P.52094, same data, stn TAS-391 ; 6 specimens, AM P.52146, same data, 9–10 April 1994, stn TAS-409 ; 1 specimen, AM P.52147, same data, 200 m, stn TAS-410 . South Australia: 11 specimens, SAM C6948 , Wedge Island , 35°11.00’S 136°29.85’E, 10 m, baited trap set overnight, 22 March 2001, V. Martin, Waterhouse Club Expedition ; 3 specimens, SAM C6947 , Dangerous Reef, Spencer Gulf , approx. 34°49’S 136°12’E, dredged, K. Sheard ; 6 females, 1 immature male, SAM C6949 , North Cove, Pearson Island , 33°56.30’S 134°15.9’E, 25 m, baited trap set overnight, 17–18 March 2001, V. Martin, Waterhouse Club Expedition .

Type locality. East of Fortescue Bay , north of Hippolyte Rocks, Tasmania, Australia, 43°06.70'S 148°03.45'E, 100 m depth .

Etymology. The species is named for its type locality.

Diagnostic description. Head lateral cephalic lobe rounded, apically rounded; eyes apparently absent. Antenna 1 peduncular articles 1 and 2 without anterodistal lobe; accessory flagellum not forming cap, terminal article not offset; flagellum with strong 2-field callynophore, robust setae absent from proximal articles; calceoli absent. Antenna 2 peduncular article 3 short; articles 4 and 5 not enlarged; flagellum short, calceoli absent. Epistome/Upper lip separate; epistome slightly produced beyond upper lip, broadly rounded; upper lip slightly produced, straight. Mandible molar with asymmetrically reduced column, proximally setose, distally triturating; palp attached about midway, article 3 with proximal A3-seta. Maxilla 1 outer plate setal-tooth 7 left and right asymmetrical, left cuspidate along most of sinusoidal inner margin, right cuspidate along most of curved inner margin; palp distal margin with apical robust setae. Maxilliped basis without recurved hook; outer plate with 1 short apicolateral robust seta and 3 short apical robust setae.

Gnathopod 1 subchelate; coxa small (length 1.1 x breadth), subtriangular, tapering distally; basis moderately setose along anterior margin; ischium short; carpus long, longer than propodus, without posterior lobe; propodus small, margins subparallel, sparsely setose along posterior margin, palm slightly acute, entire, straight. Gnathopod 2 palm transverse. Pereopod 4 coxa without distinct lateral ridge, with a well-developed posteroventral lobe. Pereopod 5 coxa without distinct lateral ridge, without umbo; basis about as long as broad, without photophore, not posteroproximally excavate, posterior margin not serrate. Pereopod 7 basis posterodistally produced less than halfway along merus, not posterodistally excavate.

Pleonites 1–3 without mid-dorsal carina, not produced dorsodistally. Epimeron 3 posterior margin smooth, posteroventral corner subacutely produced. Urosomite 1 not projecting over urosomite 2, with deep notch and subtriangular, subacute boss. Uropods 1 and 2 outer rami with distal stout striated robust setae. Uropod 2 inner ramus without constriction. Uropod 3 peduncle without dorsolateral flange, with 2 short apicomedial robust setae; inner and outer rami well developed, outer ramus article 2 short, without plumose setae on rami. Telson deeply cleft, with dorsal robust setae, with 2 apical robust setae on each lobe.

Male (sexually dimorphic characters). Head lateral cephalic lobe a semidome, apically subacute. Antenna 1 calceoli present, proximal calceolus very large. Antenna 2 flagellum long, calceoli present, proximal calceolus very large. Epimeron 3 posteroventral corner narrowly rounded. Urosomite 1 with wedge-shaped boss, obliquely truncated apically. Uropod 3 with plumose setae on both rami.

Remarks. Tryphosella fortescue belongs to a group of Australian species ( T. fortescue , T. freycinet , T. orana , T. sorell , T. tathra and T. tuckanarra ) in which some or all of the robust setae on the outer ramus of uropods 1 and/ or 2 are stouter than the others and have longitudinal striations. This group also share the characters of: no robust setae on antenna 1 flagellum, no long apical robust setae on the maxilliped outer plate, gnathopod 1 basis with a weakly setose anterior margin and a short ischium, urosomite 1 with some form of irregular or triangular boss and no plumose setae on uropod 3 of the females. They vary in: the shape of the lateral cephalic lobe, the number of apical robust setae on the maxilliped outer plate, the size of coxa 1, the angle of the gnathopod 2 palm, the shape of the boss on urosomite 1, the number of stout striated setae on uropods 1 and 2, the number of short apicomedial robust setae on the peduncle of uropod 3 and the number of apical robust setae on each lobe of the telson. It is interesting that all six species occur in southern Australia; none of the species from Queensland or nearby Papua New Guinea and New Caledonia have these unusual robust setae.

Of these six species all but T. tuckanarra have a significantly shortened subtriangular coxa 1 (about as long as broad). Only T. fortescue and T. sorell have a transverse palm on gnathopod 2. Tryphosella fortescue differs from T. sorell in having a subtriangular, subacute boss on urosomite 1 (rounded in T. sorell ) and 2 short apicomedial robust setae on uropod 3 peduncle (1 in T. sorell ).

Although T. fortescue occurred off the coast of New South Wales and South Australia it was captured most frequently off eastern Tasmania down to 200 m depth (up to 300 specimens in a trap).

Distribution. New South Wales, Tasmania and South Australia, eastern and southern Australia; 10–200 m depth.

Figures

FIGURE 24. Tryphosella fortescue sp. nov. Holotype, female, 5.4 mm, AM P. 71619; paratype, male, 5.0 mm, AM P.71620; east of Fortescue Bay, Tasmania. Scales represent 0.2 mm.

FIGURE 25. Tryphosella fortescue sp. nov. Holotype, female, 5.4 mm, AM P. 71619, east of Fortescue Bay, Tasmania. Scales represent 0.2 mm.

FIGURE 26. Tryphosella fortescue sp. nov. Holotype, female, 5.4 mm, AM P. 71619; paratype, male, 5.0 mm, AM P.71620; east of Fortescue Bay, Tasmania. Scales represent 0.2 mm.