HAPLONISCIDAE Hansen, 1916

George, Robert Y., 2004, Deep-sea asellote isopods (Crustacea, Eumalacostraca) of the north-west Atlantic: the family Haploniscidae, Journal of Natural History 38 (3), pp. 337-373 : 340-341

Family HAPLONISCIDAE Hansen, 1916

Synonym: Haploniscini Hansen, 1916: 28.

Haploniscidae : Gurjanova, 1933: 402; Menzies, 1962: 94; Wolf, 1962: 49; Menzies and George, 1972: 107; Lincoln, 1985b: 659.

Diagnosis. Janiroidea with free cephalon; blind; oval or subrectangular body, dorsoventrally flattened; all pereonites wider than long, free or fused. Pleotelson composed of a single somite, fused with last pereonite in some genera. Anus separated from branchial chamber by robust pre-anal bar. Antenna shorter than body, antenna 1 shorter than 2. Mandible with incisor and lacinia only on left mandible, molar elongate and truncated, palp three-segmented with article 3 reflexed. Pereopods 1–7 ambulatory, dactylus with single claw. Uropods small, uniramous, ventral, subterminal, one- or two-segmented.

Key to the genera of Haploniscidae (figures 2, 3)

1 Pleotelson with posterior part tapering to a blunt point........ 2

– Pleotelson truncated or broadly rounded posteriorly......... 3

2 Uropods not concealed, set close together, ventral to the anal valves; female opercular

pleopod fringed with long plumose distal setae. Aspidoniscus Menzies and Schultz, 1968 – Uropods concealed; female opercular pleopod fringed with simple short marginal setae

................. Abyssoniscus Birstein, 1971

3 Antenna 2 with peduncular articles flattened, article 3 elongate and grooved, article 4

short, articles 5 and 6 fused and apically prolonged, flagellum small and slender, subterminal (figure 2C).......... Antennuloniscus Menzies, 1962

– Antenna 2 unmodified................. 4

4 Pereonites 5–7 free (figure 3D)......... Chandraniscus n. gen. – Pereonites 5 and 6 fused, or 6 and 7 fused, or 7 fused with pleotelson, or 5–7 and

pleotelson fused together................. 5

5 Pereonites 5–7 fused with the pleotelson to form a single segment (figure 2B)....

................. Hydroniscus Hansen, 1916 – Pereonites 5 and 6 fused, or 6 and 7 fused, with pleotelson........ 6

6 Pereonites 5–7 without any pronounced anterolateral angles in anterior pereonites. 7

– Pereonites 5–7 free, with one or more pereonites 2–4 having prolonged anterolateral

angles (figure 3B)........... Chauliodoniscus Lincoln, 1985

7 Pereonites 5–7 fused between each other, and pereonite 7 fused or not fused with

pleotelson but pereonite 7 not reduced (figure 2A).. Haploniscus Richardson, 1908 – Posterior pereonites fused mid-dorsally between each other and with pleotelson, and pereonite 7 much reduced in adult, conspicuously shorter and narrower than pereonite

6, and pleotelson with posterolateral angles conspicuously produced (figure 3C)...

................. Mastigoniscus Lincoln, 1985