Microlysias soela, Lowry & Kilgallen, 2014

Lowry, J. K. & Kilgallen, N. M., 2014, New tryphosine amphipods from Australian waters (Crustacea, Amphipoda, Lysianassoidea, Lysianassidae, Tryphosinae), Zootaxa 3844 (1), pp. 1-64 : 19-22

Microlysias soela sp. nov.

( Figs 13–15 )

Microlysias xenokeras .— Azman & Othman, 2013: 14 , fig. 9.

Types. Holotype female 5.5 mm, AM P.68958, North West Shelf, Western Australia, (19°58.4’S 117°49.2’E), 43 m, sled, 26 June 1983, CSIRO Division of Fisheries, FRV Soela stn 03-D4-S . Paratypes: 33 specimens, 3.2–5.6 mm, AM P.68959, with same collection details as holotype ; 2 specimens, AM P.68960, North West Shelf , Western Australia, Australia (19°59.2’S 117°48.6’E), 41 m, sled, 26 June 1983, CSIRO Division of Fisheries, FRV Soela stn 03-D8-S ; 1 male, 6.0 mm, NMV J67527 , North-West Shelf between Port Hedland and Dampier, Western Australia, Australia (20°01.00’S 117°11.00’E – 20°01.00’S 117°12.00’E), 48 m, WHOI epibenthic sled, 11 June 1983, G.C.B. Poore & H.M. Lew Ton, FRV Soela [stn NWA-48] .

Additional material examined. 1 male, NMV J67528 North-West Shelf between Port Hedland and Dampier, Western Australia, Australia (20°01.00’S 117°11.00’E –20°01.00’S 117°12.00’E), 48 m, WHOI epibenthic sled, 11 June 1983, G.C.B. Poore & H.M. Lew Ton, FRV Soela [stn NWA-48] ; 23 specimens, NMV J67529 , North-West Shelf between Port Hedland and Dampier, Western Australia, Australia (20°01.00’S 117°11.00’E –20°01.00’S 117°12.00’E), 48 m, WHOI epibenthic sled, 11 June 1983, G.C.B. Poore & H.M. Lew Ton, FRV Soela [stn NWA-48] ; 1 female, NMV J67530 , North-West Shelf between Port Hedland and Dampier, Western Australia, Australia (20°01.00’S 117°11.00’E –20°01.00’S 117°12.00’E), 48 m, WHOI epibenthic sled, 11 June 1983, G.C.B. Poore & H.M. Lew Ton, FRV Soela [stn NWA-48] ; 1 specimen, NMV J67531 , North-West Shelf between Port Hedland and Dampier, Western Australia, Australia (19°38’S 118°06’E –19°37’S 118°05’E), 49 m, crinoids, WHOI epibenthic sled, 13 June 1983, G.C.B. Poore & H.M. Lew Ton, FRV Soela [stn NWA-56] ; 1 specimen, NMV J67532 , North-West Shelf between Port Hedland and Dampier, Western Australia, Australia (19°00.5’S 117°26.0’E –19°00.5’S 117°46.23’E), 120 m, WHOI epibenthic sled, 12 June 1983, G.C.B. Poore & H.M. Lew Ton, FRV Soela [NWA-52] ; 1 specimen, NMV J67533 , North-West Shelf between Port Hedland and Dampier, Western Australia, Australia (20°01.00’S 117°17.00’E –20°00.00’S 117°18.00’E), 46 m, WHOI epibenthic sled, 2 June 1983, G.C.B. Poore & H.M. Lew Ton, FRV Soela [NWA-5] .

Type locality. North West Shelf , Western Australia, Australia (19°58.4’S 117°49.2’E) ; 43 m depth.

Etymology. Named for the FRV Soela; used as a noun in apposition.

Description. Based on holotype female, 5.5 mm, AM P.68958. Head lateral cephalic lobe subtriangular, apically subacute; eyes irregularly subrectangular, covering most of head. Antenna 1 accessory flagellum forming a partial operculum, 3-articulate; primary flagellum with strong 2-field callynophore, robust setae absent from proximal articles; calceoli absent. Antenna 2 peduncular article 3 short; articles 3 to 5 not enlarged; flagellum short, calceoli absent. Labrum, epistome and upper lip fused, broadly rounded, concave. Mandible molar ridge-like, narrow, setose with narrow distal triturating surface; palp attached about midway, article 3 with 1 proximal A3-setae. Maxilla 1 inner plate apically produced into a slender spine; outer plate setal-tooth 7 present, left and right symmetrical, cuspidate distally; palp distal margin with apical robust setae. Maxilliped outer plate with 1 short apical robust seta.

Pereonites 1–7 dorsally smooth. Gnathopod 1 subchelate; coxa large, about as long as coxa 2, subrectangular, with concave anterior margin, distally straight; basis moderately setose along anterior margin; ischium short; carpus compressed, shorter than propodus, with narrow posterior lobe; propodus small, margins subparallel, sparsely setose along posterior margin, palm transverse, entire, straight. Gnathopod 2 minutely chelate; propodus palm moderately obtuse. Pereopod 4 coxa with a well-developed posteroventral lobe. Pereopod 5 basis slightly broader than long, not posteroproximally excavate, posterior margin weakly serrate. Pereopod 7 basis posterodistally produced less than halfway along merus.

Pleonite 3 without mid-dorsal carina, not produced dorsodistally, posterodorsal margin not produced. Epimeron 3 posterior margin smooth, posteroventral corner broadly rounded. Urosomite 1 with anterodorsal notch and slightly rounded boss. Uropod 2 inner ramus without constriction. Uropod 3 inner and outer rami well developed, outer ramus article 2 short, with plumose setae on both rami. Telson deeply cleft, longer than wide, with 2–3 dorsal robust setae per lobe and 1 apical robust setae on each lobe.

Sexually dimorphic characters. Based on male, 6.0 mm, NMV J67527 . Antenna 1 primary flagellum with strong 2-field callynophore (stronger than female); calceoli present, small. Antenna 2 peduncular article 3 short; article 5 greatly enlarged; flagellum long, calceoli present.

Remarks. The only other recognised species of Microlysias , M. xenokeras Stebbing, 1918 , is known from south-western South Africa. A second species, M. indica K.H. Barnard, 1937 , from the south Arabian coast is considered by Griffiths (1975) to be a synonym of M. xenokeras .

Microlysias soela sp. nov. is very similar to M. xenokeras . The gnathopod 2 palm in M. xenokeras is extremely obtuse (almost at a right angle), but only moderately obtuse in M. soela and the antenna 2 peduncle article 3 is longer in the female of M. xenokeras . Microlysias soela also has a distinct spine-like projection from the apical margin of the maxilla 1 inner plate that is absent in M. xenokeras .

Based on the less obtuse palm of gnathopod 2 the record of M. xenokeras from Pulau Tioman ( Azman & Othman 2013) appears to be M. soela .

Depth range. 41–120 m (this study).

Distribution. Australia. North West Shelf, Western Australia (this study). Malaysia. Pulau Tioman ( Azman & Othman 2013).

Figures

FIGURE 13. Microlysias soela sp. nov., habitus, paratype, male, 6.0 mm, NMV J67527, North-West Shelf, Western Australia.

FIGURE 14. Microlysias soela sp. nov., holotype, female AM P.68958; paratype, male A1, 2, NMV J67527, from North-West Shelf, Western Australia. Scale: antennae, 0.2 mm; mouthparts, 0.1 mm.

FIGURE 15. Microlysias soela sp. nov., holotype, female AM P.68958; paratype, male U3, NMV J67527, from North-West Shelf, Western Australia. Scale: 0.2 mm.