Thrombasia saros sp. nov.

(Figs 17–19)

Types. Holotype, female, 13.5 mm, NMV J46814, from 76 km south of Point Hicks, Victoria, Australia (38°29.33'S 149°19.98'E), 1840 m, sandy mud, fine shell, WHOI epibenthic sled, coll. G.C.B. Poore et al, RV Franklin, 26 October 1988 . Paratypes, 4 specimens (1 damaged), 5.1–10.0 mm, NMV J16318, same collection details as holotype .

Type locality. South of Point Hicks, Victoria, Australia (38°29.33'S 149°19.98'E), 1840 m depth .

Etymology. Named for the SS Saros, the wreck of a steamship visible on the rocks at Point Hicks, Victoria; used as a noun in apposition.

Description. Based on holotype, female, 13.5 mm. Head lateral cephalic lobe subtriangular, apically subacute; eyes apparently absent. Antenna 1 accessory flagellum forming cap partially covering callynophore, 5-articulate; primary flagellum with strong 2-field callynophore; calceoli absent. Antenna 2 peduncular article 3 short; articles 3 to 5 not enlarged, with brush setae on articles 4 and 5; flagellum short, calceoli absent. Labrum, epistome and upper lip separate; epistome less produced than upper lip, very slightly concave; upper lip produced, rounded apically. Mandible molar columnar, with oval fully triturating surface; palp attached distally, article 3 with 1 proximal A3- seta. Maxilla 1 outer plate setal-tooth 7 present, left and right symmetrical, cuspidate distally; palp distal margin with apical robust setae. Maxilliped outer plate with 4 long, broad apical robust setae and 2 long, slender apical robust setae.

Pereonites 1–7 dorsally smooth. Gnathopod 1 weakly subchelate; coxa large, about as long as coxa 2, slightly tapering distally; basis densely setose along anterior margin; ischium short; carpus long, longer than propodus, without posterior lobe; propodus small, margins tapering distally, sparsely setose along posterior margin, palm slightly acute, entire, straight. Gnathopod 2 propodus palm transverse. Pereopod 4 coxa with a welldeveloped posteroventral lobe. Pereopod 5 basis slightly longer than broad, not posteroproximally excavate, posterior margin not serrate. Pereopod 7 basis posterodistally produced not reaching merus.

Pleonite 3 without mid-dorsal carina, not produced dorsodistally, posterodorsal margin not produced. Epimeron 1 anterodistal corner produced, forming small upturned spine. Epimeron 3 posterior margin smooth, posteroventral corner rounded. Urosomite 1 not projecting over urosomite 2, dorsally straight. Uropod 2 inner ramus with strong constriction. Uropod 3 inner and outer rami well developed, outer ramus article 2 short, without plumose setae on rami. Telson m oderately cleft, with 2 dorsal robust setae per lobe and 1 apical robust setae on each lobe.

Sexually dimorphic characters. Unknown.

Habitat. Sandy mud and fine shell.

Depth range. 1840 m (this study).

Remarks. Based on the rounded posteroventral corner of epimeron 3, this species is most similar to Thrombasia rotundata and T. evalina . It is easily distinguished from these species by its longer and more weakly tapered gnathopod 1 coxa, by the propodus which is distinctly narrower than the carpus, and by the poorly defined palm.

Distribution. Bass Strait. Off the coast of Victoria, Australia (this study).