Gnathostenetroididae Kussakin, 1967

Malyutina, Marina V. & L. Bruce, Niel, 2019, The first record of Gnathostenetroididea Kussakin, 1967 from Australian waters with description of four new species of Gnathostenetroides Amar, 1957 (Crustacea: Isopoda: Asellota) from the Great Barrier Reef, Zootaxa 4554 (2), pp. 301-350 : 304

Family Gnathostenetroididae Kussakin, 1967

Diagnosis: Body with subparallel lateral margins, cephalon with rostral projection of varying size; eyes, if present, dorsolaterally rounded, of 3–8 ommatidia. Pleon subequal in size to two posterior pereonites, two pleonites anterior to pleotelson. Pereopods 1–4 inserted anteriorly, bases directed posteriorly; dorsal margin of pereopod articles oriented anteriorly. Pereopods 5–7 inserted posteriorly, bases directed anteriorly; dorsal margin of pereopod articles oriented posteriorly. Pereopods 2–7 dactylus with two strong, subequal claws. Pereopod 1 largest, subchelate, with broad enlarged prododus. Pereopod 1 of male longer and more stout than in female. Penes tubular, inserted from coxae of pereopods 7. Pleopod 1 of male longer than branchial cavity, covering remaining pleopods; protopod short, fused, rami separate, broad, lamellar. Pleopod 2 of male separate, less than half pleopod 1 length, exopod short, stout, inserting distomedially on protopod; copulatory stylet of endopod widening distally to setal fringed structure. Female pleopod 2 fused, covering remaining pleopods. Pleopod 3 endopod with 3 distal plumose setae; exopod elongate, slender. Pleopod 4 biramous, pleopod 5 uniramous. Uropods inserted ventrally adjacent to anus, protopod stout, rami relatively well developed. Anus not covered by pleopods, separated from pleopod chamber by preanal bar.

Remarks. The Gnathostenetroididae can be identified and distinguished from the Protojaniridae by the presence of two free (unfused) pleonites, while Protojaniridae is characterized by absence of free pleonites.