Lysianella G. O. Sars 1883

Lysianella lui sp. nov.

(Figs 6–8)

Types. Holotype, female, 4.8 mm, NMV J67536, 54 km east-south-east of Nowra, New South Wales, Australia (34°52.72'S 151°15.04'E), 996 m, mud, fine sand, fine shell, WHOI epibenthic sled, 22 October 1988, G.C.B. Poore et al., RV Franklin, SLOPE stn 53. Paratypes: 6 specimens, 3.7–4.3 mm, NMV J67537, same collection details as holotype.

Additional material examined. 1 specimen, NMV J67538, off Nowra, New South Wales, Australia (34°52.29'S 151°15.02'E), 1096 m, shell, WHOI epibenthic sled, 15 July 1986, coll. G.C.B. Poore and C.C. Lu, RV Franklin SLOPE stn 7; 1 specimen, NMV J14608, south of Point Hicks, Victoria, Australia (38°25.90'S 148°58.60'E), 1850 m, muddy, sandstone, WHOI epibenthic sled, 22 July 1986, G.C.B. Poore et al., RV Franklin SLOPE stn 25; 2 specimens, NMV J67539, off Freycinet Peninsula, Tasmania, Australia (42°2.20 'S 148°38.70'E), 800 m, coarse shelly sand, WHOI epibenthic sled, 27 July 1986, M.F. Gomon et al., RV Franklin, SLOPE stn 45; 1 specimen, NMV J7659, Eastern Bass Strait, 112 km south-south-east of Cape Conran, Victoria, Australia (38º49.0’S 149º00.9’E), 2450 m, mud, pipe dredge, 16 November 1981, coll. R. Wilson, RV Tangaroa stn BSS Q-636.

Type Locality. 54 km east-south-east of Nowra, New South Wales, Australia (34°52.72'S 151°15.04'E), 996 m depth.

Etymology. Named for Chung-Cheng Lu, one of the collectors of this species.

Description. Based on holotype female, 4.8 mm, NMV J67536. Head lateral cephalic lobe subtriangular, apically subacute; eyes apparently absent. Antenna 1 accessory flagellum forming operculum partially covering callynophore, 3-articulate; primary flagellum with weak 2-field callynophore, robust setae absent from proximal articles; calceoli absent. Antenna 2 peduncular article 3 short; article 4 enlarged; flagellum short, calceoli absent. Labrum, epistome and upper lip separate; epistome less produced than upper lip, concave; upper lip produced, subacute apically. Mandible molar with reduced column and reduced triturating surface; palp attached about midway. 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 2 short apical robust setae; palp article 4 poorly developed.

Pereonites 1–7 dorsally smooth. Gnathopod 1 weakly subchelate; coxa large, about as long as coxa 2, subrectangular with straight anterior margin; basis sparsely setose along anterior margin; ischium short; carpus short, subequal in length to or slightly shorter than propodus, without posterior lobe; propodus small, margins slightly tapering distally, sparsely setose along posterior margin, palm strongly acute, entire, straight. Gnathopod 2 minutely chelate; propodus palm moderately obtuse. Pereopod 4 coxa with a well-developed posteroventral lobe. Pereopod 5 basis about as long as broad, posteroproximally excavate, posterior margin not serrate. Pereopod 7 basis posterodistally less than halfway along merus.

Pleonite 3 without mid-dorsal carina, posterodorsal margin produced, truncated. Epimeron 3 posterior margin smooth, posteroventral corner subacute. Urosomite 1 dorsally straight. Uropod 2 inner ramus without constriction. Uropod 3 inner and outer rami well developed, outer ramus article 2 long, without plumose setae on rami. Telson apically notched, longer than wide, with 6–8 dorsal robust setae and 2 apical robust setae.

Sexually dimorphic characters. Not known.

Remarks. Lysianella lui is very similar to Lysianella mimica (J.L. Barnard, 1962). The most outstanding difference between these species is the maxilliped palp article 4 which is reduced and blunt in L. lui sp. nov., but well-developed in L. mimica. Lysianasella lui is also similar to L. morbihanensis (Bellan-Santini & Ledoyer, 1974) from the Kerguelen Islands, but the latter species apparently lacks a fourth article on the maxilliped palp, and the posteroventral lobe on pereopod 4 is not as strongly developed as in L. lui. Lysianella lui is the only species in the genus with no constriction on uropod 2, otherwise diagnostic for the genus.

Depth range. 800–2450 m.

Distribution. Australia. Eastern and south-eastern coasts, from Nowra, New South Wales to the Freycinet Peninsula, Tasmania.