Izinkalidae, Lowry & Stoddart, 2010

Lowry, J. K. & Stoddart, H. E., 2010, The family Izinkalidae fam. nov. (Crustacea: Amphipoda: Lysianassoidea) in Australian waters, Zootaxa 2532 (1), pp. 64-68 : 64-65

Izinkalidae fam. nov.

Diagnostic description. Head concealed, slightly longer than deep. Antennae calceoli absent. Antenna 1 with callynophore in male; accessory flagellum article 1 not forming a cap. Antenna 2 peduncular article 3 without distal hook. Epistome and upper lip [unknown]. Mouthpart bundle subquadrate. Mandible incisors well developed, asymmetrical, left convex, right straight; left lacinia mobilis probably absent; accessory setal row absent; molar absent; palp inserted mid-way. Maxillae 1 and 2 vestigial. Maxilliped inner and outer plates absent; palp 4-articulate, slender; article 4 vestigial.

Gnathopod 1 minutely subchelate; coxa vestigial; merus and carpus not rotated; ischium extremely long (length more than 6 x breadth); carpus and propodus elongate, rectolinear; propodus with large robust seta on short palm; dactylus truncated. Gnathopod 2 chelate; coxa large, subequal in size to coxa 3; ischium very long; carpus subrectangular, with palmate setae; propodus subovate, with palmate setae; dactylus minute. Pereopods all simple; distal spurs absent. Pereopod 4 coxa with well developed posteroventral lobe. Pereopod 5 coxa anterior lobe deeper than posterior lobe. Pereopod 6 coxa anterior lobe slightly deeper than posterior lobe.

Uropod 2 inner ramus without constriction. Uropod 3 biramous. Telson entire.

Type genus. Izinkala Griffiths, 1977 .

Generic composition. Izinkalidae includes one genus: Izinkala Griffiths, 1977 .

Remarks. Griffiths (1977) remarked on the similarities of Izinkala to Clepidecrella J.L. Barnard, 1962 and Kerguelenia Stebbing, 1888 . We agree that both groups have reduced mouthparts and similarly shaped first gnathopods. But we have no way of knowing if the mouthpart reductions are homoplasious between the taxa. For example, in kergueleniids the inner and outer plates of the maxillipeds are reduced, but in izinkalids they are completely absent and the well developed fourth articles of the palps of kergueleniids are vestigial in izinkalids. Antenna 1 has a completely different structure across these groups – unmodified in kergueleniids and highly modified in izinkalids. The coxa of gnathopod 1 is vestigial in Izinkala , a condition never found in kergueleniids, and although the gnathopods are long and slender in both groups, Izinkala has an extremely long ischium and the dactylus is a short, blunt instrument not at all similar to the filiform dactylus of kergueleniids.

Griffiths (1977) also mentions the similarity of Izinkala to Lepidepecreum , particularly L. clypodentatum J.L. Barnard, 1962 . We see similarities in overall body shape and in the shape of the seventh pereopods, but the severe reduction in mouthpart morphology and the completely different first gnathopods makes statements about relationships tenuous.

At this stage we find it difficult to align the izinkalids with other lysianassoid family-level taxa.