Austrocallisoma, Kilgallen & Lowry, 2015

Kilgallen, Niamh M. & Lowry, James K., 2015, A review of the scopelocheirid amphipods (Crustacea, Amphipoda, Lysianassoidea), with the description of new taxa from Australian waters, Zoosystematics and Evolution 91 (1), pp. 1-43 : 8

Austrocallisoma gen. n.

Type species.

Austrocallisoma jerryi sp. n., by original designation.

Included species.

Austrocallisoma includes one species: Austrocallisoma jerryi sp. n.

Diagnostic description.

Mandible lacinia mobilis a stemmed distally expanded, irregularly cusped blade. Maxilla 1 inner plate with pappose setae lining inner margin; palp 1-articulate. Maxilla 2 inner plate broader than outer, inner and outer plates subequal in length. Maxilliped palp article 4 vestigial. Gnathopod 1 coxa reduced, slightly shorter than coxa 2, margins slightly tapering distally; basis swollen, without glandular material; dactylus reduced, simple. Pereopod 3 carpus short to long, longer than wide. Pereopod 4 with well-developed, subacute posteroventral lobe.

Etymology.

The name is a combination of the prefix Austro - from the latin australis, meaning southern and referring to the southern hemisphere distribution of the type species, and the suffix - callisoma (gender neuter) referring to its placement within the Paracallisominae .

Discussion.

Austrocallisoma gen. n. is a difficult taxon that has much in common with the monotypic genera Anisocallisoma , Eucallisoma and Tayabasa gen. n. Having four monotypic genera that are highly derived yet clearly closely related is not ideal. However, to maintain consistency of diagnostic characters at a generic level we feel justified in establishing this new genus.

Austrocallisoma can be separated from both Eucallisoma and Anisocallisoma by the strongly developed and subacute posteroventral lobe on the pereopod 4 coxa (well-developed and subquadrate in Eucallisoma , very weakly-developed and subacute in Anisocallisoma ). It can be further distinguished from Anisocallisoma in having plumose setae lining the inner margin of the inner plate of maxilla 1, and having a distal tuft of setae on the accessory flagellum. It differs from Eucallisoma in having a vestigial maxilliped palp article 4 (well-developed in Eucallisoma ).