Pseudambasia lochi, Kilgallen, N. M. & Lowry, J. K., 2013

Kilgallen, N. M. & Lowry, J. K., 2013, The lysianassid genus Pseudambasia in Australian waters (Crustacea, Amphipoda, Lysianassidae, Lysianassinae), Zootaxa 3710 (4), pp. 301-321 : 307-309

Pseudambasia lochi sp. nov.

( Figs 4–6 )

Type material. Holotype, female, 3.9 mm, AM P.68940, 19 km from Mt Young, toward Wallaroo, Spencer Gulf, South Australia (33°18'S 137°31'E), 18 m, K. Sheard, 8 March 1938. Paratypes: 1 female, 5.1 mm, AM P.68941; 1 specimen (? male), 3.3 mm, AM P. 68866; 1 male, 3.7 mm, AM P.68942; all same locality information as holotype.

Additional material examined. 1 female, 3.9 mm, AM P.68861, southeast side of Gabo Island, Victoria (37º34’S 149º55’E), 1 m, P.A. Hutchings, 14 February 1973. 2 specimens, AM P.68868, Australia, South Australia, north-east of Wardang Island, Spencer Gulf (34°30'S 137°22'E), dredge, 7.2 m, K. Sheard, 12 March 1938; 1 male, 4.5 mm, AM P.68865, Australia, South Australia, Bay of Shoals, Kangaroo Island, (35°37'S 137°36'E), algae, 0 m, I. Loch, E.K. Yoo & K. Handley, 7 March 1978.

Type locality. 19 km from Mt Young, toward Wallaroo, Spencer Gulf, South Australia (33°18'S 137°31'E).

Etymology. Named for Ian Loch, one of the collectors.

Description. Based on holotype, female, 3.9 mm, AM P.68940. Head lateral cephalic lobe broadly rounded; eyes oval. Antenna 1 short; peduncular article 1 short, length 1.4 × breadth, without dorsal lobe; peduncular article 2 long, 1.6 × article 1; peduncular article 3 long; 0.25 × article 1; accessory flagellum short, 0.16 × primary flagellum, 2-articulate, article 1 short; primary flagellum 9-articulate, without callynophore, with aesthetascs on most flagellar articles. Antenna 2 flagellum 4-articulate. Mandible accessory setal row with 4 multiserrate setae; molar reduced, represented by finely setose triangular flap; palp attached extremely proximally; article 1 long, length 2.9 × breadth; article 3 slender, blade-like, with distal crease. Maxilla 1 inner plate with small sharp apical robust seta; outer plate broad, with 11 setal teeth, setal teeth 1 – 5 of outer row with cusps in 2 rows; palp 2- articulate, apical margin with 3 sharp spines and 2 robust setae. Labium outer lobes without distolateral stylets. Maxilliped inner plate without apical nodular robust setae; distolateral corner with distinct sharp spine and large robust seta.

Gnathopod 1 weakly subchelate; coxa anterior margin slightly concave, anteroventral corner rounded, coxa posterior margin straight; carpus short, length 1.6 × breadth, subequal in length to propodus; propodus subtriangular, length 1.6 × breadth, palm extremely acute, margin straight, rugose. Gnathopod 2 carpus long, length 4 × breadth; palm transverse, with slightly convex margin. Pereopod 5 coxa equilobate. Pereopod 6 coxa not produced; basis posterodistal corner produced beyond ischium, forming rounded lobe. Pereopod 7 basis expanded posteriorly, posterodistal margin oblique, posterodistal corner moderately produced, forming lobe produced halfway along merus; merus slightly expanded posteriorly.

Epimeron 3 posteroventral corner subquadrate. Uropod 1 outer ramus slightly longer than inner ramus. Uropod 2 outer ramus slightly longer than inner ramus; inner ramus with strong constriction. Uropod 3 peduncle short, with small dorsolateral flange; rami slender. Telson as long as broad, length 0.9 × breadth, lateral margins subparallel to slightly converging distally; apical margin straight.

Sexually dimorphic characters. Based on male, AM P.68942. Gnathopod 1 subchelate; propodus length 1.4 × breadth; palm acute.

Remarks. Pseudambasia lochi appears to be most similar to P. nui from Fiji. Both have a strongly constricted inner ramus on uropod 2, a narrowly rounded/subquadrate posteroventral corner on epimeron 3, but P. nui has a weakly subchelate female gnathopod 2 and an extremely long carpus on gnathopod 2. The telson of P. l o c h i is also very different to that of P. n u i, the lateral margins of which are more strongly tapering in P. n u i and the apical margin is subacute.

Distribution. Gabo Island, Victoria to Spencer Gulf, South Australia.

Figures

FIGURE 4. Pseudambasia lochi sp. nov., female habitus, 3.9 mm, AM P. 68861, Spencer Gulf, South Australia.

FIGURE 5. Pseudambasia lochi sp. nov., holotype, female, 3.9 mm, AM P. 68940, Spencer Gulf, South Australia. Scale bars: 0.2 mm.

FIGURE 6. Pseudambasia lochi sp. nov., holotype, female, 3.9 mm, AM P. 68940, paratype male AM P. 68942, Spencer Gulf, South Australia. Scale bar: 0.2 mm.