Pseudambasia ponderi, 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 : 310-312

Pseudambasia ponderi sp. nov.

( Figs 7 , 8 )

Type material. Holotype, female, 2.7 mm, AM P.68946, Hospital Point, Thursday Island, Torres Strait, Queensland, Australia (10°35'S 142°13'E), algal washings, W.F. Ponder & I. Loch, 29 June 1976. Paratypes: male, 1.9 mm, AM P.68947; 2 specimens, AM P.68811, same locality as holotype.

apically subacute; eyes oval. Antenna 1 short; peduncular article 1 short, length 1.4 × breadth, without dorsal lobe; peduncular article 2 short, 0.43 × article 1; peduncular article 3 long, 0.26 × article 1; accessory flagellum medium length, 0.36 × primary flagellum, 2-articulate, article 1 long, 1.2 × article 2; primary flagellum 7-articulate, without callynophore, flagellum with aesthetascs on most flagellar articles. Antenna 2 flagellum 4-articulate. Mandible accessory setal row with 2 simple setae; molar reduced, represented by a tongue-like flap; palp attached extremely proximally; article 1 long, length 2 × breadth; article 3 slender, blade-like, tapering into a long flagellate-like tip. Maxilla 1 outer plate broad with 10 setal teeth, setal teeth of outer row with cusps in 1 row; palp 2-articulate, without apical setae; palp with irregular apical margin. Maxilla 2 inner and outer plates broad; inner plate length 1 × outer plate. Labium outer lobes unknown. Maxilliped inner plate with apical robust seta and 2 subapical robust setae.

Gnathopod 1 subchelate; coxa anterior margin slightly concave, anteroventral corner rounded, posterior margin straight to very slightly concave; carpus short, length 1.4 × breadth, shorter than (0.73 ×) propodus; propodus subtriangular, length 1.8 × breadth, palm acute to extremely acute, margin concave, finely serrate. Gnathopod 2 minutely subchelate; carpus long, length 3.7 × breadth; palm transverse, with straight margin. Pereopod 5 coxa equilobate; basis posteroventrally produced into small lobe. Pereopod 6 coxa not produced; basis posterodistal corner produced beyond ischium, forming subacute lobe. Pereopod 7 basis expanded posteriorly, posterodistal margin excavate, posterodistal corner narrowly rounded, not produced beyond ischium; merus slightly expanded posteriorly.

Epimeron 3 posteroventral corner produced, subacute. Uropod 1 outer ramus slightly longer than inner ramus. Uropod 2 outer ramus slightly longer than inner ramus; inner ramus without constriction. Uropod 3 peduncle short, without dorsolateral flange; rami slender, subequal in length. Telson longer than broad, length 1.2 × breadth, lateral margins converging distally, apical margin subacute.

Sexually dimorphic characters. Based on male, 1.9 mm, AM P.68947. Antenna 1 with strong 1-field callynophore, flagellum with aesthetascs. Gnathopod 1 subchelate; palm acute to extremely acute, margin concave, irregular to weakly serrate.

Remarks. Pseudambasia ponderi is a distinctive species with a small subtriangular lateral cephalic lobe, an excavate posteroventral corner on the basis of pereopod 7 (similar to P. rossii ), a produced subacute posteroventral corner on epimeron 3, long, slender rami on uropod 1 (similar to P. indentata ) and a non-constricted inner ramus on uropod 2.

Distribution. Thursday Island, Torres Strait, Queensland.

Figures

FIGURE 7. Pseudambasia ponderi sp. nov., all parts from holotype, female, 2.7 mm, AM P. 68946, except A 1 from paratype male, AM P. 68947, Thursday Island, Torres Strait. Scale bars: 0.1 mm.

FIGURE 8. Pseudambasia ponderi sp. nov., all parts from holotype, female, 2.7 mm, AM P. 68946, except G 1 from paratype male, AM P. 68947, Thursday Island, Torres Strait. Scale bars: 0.1 mm.