Triaina, Just, Jean, 2009

Just, Jean, 2009, Triaina, a new genus in the Janirellidae Menzies, 1956 (Crustacea: Isopoda: Asellota), with two new species from south-eastern Australia, and a new diagnosis for the family, Zootaxa 1980, pp. 1-15 : 2

Janirellidae

The only valid diagnosis of Janirellidae is Menzies’ original one (1956a), which included only the type genus Janirella Menzies (1956) . All subsequent diagnoses, based on different combinations of included genera, are now recognised as erroneous. Menzies’ (1956a) diagnosis is brief and does not cover the current concept of the family. An amended diagnosis is presented here based on the inclusion of Dactylostylis Richardson, 1911 , Janirella Bonnier, 1896 , and Triaina gen. nov.

Diagnosis. Cephalon free, without eyes; pereon subcylindrical or flattened; pereonites with or rarely without lateral spines. Pleon with no free pleonites, lateral margins with spines or irregular denticles, posterior margin evenly rounded to strongly projecting between uropods; anus ventral, covered by opercular pleopods; pleopodal chamber open posteriorly through more or less extended dorsal groove (e.g. Fig. 3 , pt2), or groove absent. Antennula much shorter than antenna, not sexually dimorphic, article 1 much larger than succeeding articles. Antenna elongate, article 3 with articulated scale, or scale absent, articles 1–4 short, compact, 3 occasionally elongate. Mandibles with triturating apically serrate and setiferous molar, palp article 3 spoonshaped. Maxillipedal palp articles 2 and 3 expanded medially. Pereopod I carposubchelate. Pereopods II–VII ambulatory, subsimilar; dactylar main claw large, posterior claw small or absent. Male pleopod I with nearly parallel sides, slightly tapering towards rounded, truncate or deeply bifid apices. Male pleopod II stylet straight to moderately curved. Pleopod III exopod shorter than endopod, 1- or 2-articulate, without plumose setae; endopod with 3 to 7 plumose setae on distal margin. Pleopod IV with short 1-articulate exopod, or exopod lacking, endopod a simple oval sack. Pleopod V without exopod, endopod a simple oval sack. Uropods uniramous, paucisetose, rod-like, inserting posterolaterally.

Type genus. Janirella Bonnier, 1896 .

Genera included. Dactylostylis Richardson, 1911 ; Janirella Bonnier 1896 , Triaina gen. nov.

Remarks. With reference to the diagnosis presented above, Dactylostylis differs from Janirella and the new genus Triaina on the following points: pleopodal chamber closed, without posterior groove; without antennal scale on article 3; pleopod III exopod longer than endopod, 2-articulate; pleopod IV without exopod.

Figures

FIGURE 3. Triaina isodonte sp. nov. Holotype, male, except F, female paratype. op, female operculum in situ, oblique view; pl 1 – pl 5, pleopods I – V; pt 1, ventral view of pleon with pleopods in place; pt 2, ventral view of pleon with pleopods removed, exposing anus.