Pseudambasia dartnalli, 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 : 303-306

Pseudambasia dartnalli sp. nov.

( Figs 1–3 )

Type material. Holotype, female, 10.0 mm, AM P.68936, north of Schouten Island, Schouten Passage, Tasmania (42°17'S 148°18'E), Van Veen grab, coarse sand, coralline algae and weed, 12 m, A. Dartnall, 8 June 1977. Paratypes: male, 5.9 mm, AM P.68937; 9 specimens, AM P.27055, same locality information as holotype.

Type locality. North of Schouten Island, Schouten Passage, Tasmania (42°17'S 148°18'E).

Etymology. Named for collector, Alan J. Dartnall.

Diagnostic description. Based on holotype, female, 10.0 mm, AM P. 68936. Head lateral cephalic lobe distally truncated; eyes oval. Antenna 1 medium length; peduncular article 1 medium length, length 1.7 × breadth, without dorsal lobe; peduncular article 2 long, 0.8 × article 1; peduncular article 3 short, 0.25 × article 1; accessory flagellum very short, 0.15 × primary flagellum, 2-articulate, article 1 short, subequal in length to article 2; primary flagellum 17-articulate, without callynophore, without aesthetascs on most articles. Antenna 2 flagellum 15- 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 3.1 × breadth; article 3 slender, bladelike, with distal crease, apically bifurcate. Maxilla 1 inner plate without well developed setae; outer plate broad with 11 setal teeth, setal teeth of outer row with cusps in 1 row; palp 2-articulate, without apical setae. Maxilla 2 inner and outer plates broad; inner plate length 0.85 × outer plate. Labium outer lobes with distolateral stylets. Maxilliped inner plate without apical nodular robust setae; with 2 subapical robust setae.

Gnathopod 1 weakly subchelate; coxa anterior margin slightly concave, anteroventral corner rounded, posterior margin straight; carpus short, length 1.9 × breadth, subequal in length (1.1 ×) to propodus; propodus subrectangular, length 2 × breadth, palm extremely acute, margin straight. Gnathopod 2 minutely subchelate; carpus long, length 3 × breadth; palm transverse or slightly obtuse, with convex margin. Pereopod 5 coxa equilobate. Pereopod 6 coxa not lobate posteriorly; basis posterodistal corner slightly produced beyond ischium, ventrally truncated. Pereopod 7 basis expanded posteriorly, posterodistal margin slightly rounded, posteroventral corner rounded, not produced beyond ischium; merus slightly expanded posteriorly.

Epimeron 3 posteroventral margin produced into small high cusp above broadly rounded posteroventral corner. Uropod 1 rami subequal in length. Uropod 2 rami subequal in length; inner ramus with strong constriction. Uropod 3 peduncle short, with dorsolateral flange; rami slender, subequal in length. Telson as long as broad, lateral margins subparallel, apical margin straight to very slightly rounded.

Sexually dimorphic characters. Based on male, 5.9 mm, AM P.68937. Gnathopod 1 subchelate, palm extremely acute, margin straight, posterodistal corner defined by small spine and large robust seta.

Remarks. Pseudambasia dartnalli is a distinctive species characterised by a broadly rounded posteroventral corner on epimeron 3, a strongly constricted inner ramus on uropod 2 and a well-developed lateral flange on the peduncle of uropod 3 and a telson with subparallel lateral margins and a broad distal margin.

Distribution. Schouten Island, Tasmania.

Figures

FIGURE 1. Pseudambasia dartnalli sp. nov., holotype, female, 10.0 mm, AM P. 68936, Schouten Passage, Tasmania. Scale bars: 0.1 mm.

FIGURE 2. Pseudambasia dartnalli sp. nov., holotype, female, 10.0 mm, AM P. 68936, Schouten Passage, Tasmania. Scale bar: 0.2 mm.

FIGURE 3. Pseudambasia dartnalli sp. nov., holotype, female, 10.0 mm, AM P. 68936, Schouten Passage, Tasmania. Scale bars: 0.1 mm.