Pseudidotheidae Ohlin, 1901

Poore And T, Gary C. B., 2004, Pseudidotheidae (Crustacea: Isopoda: Valvifera) reviewed with description of a new species, first from Australia, Memoirs of Museum Victoria 61 (1), pp. 75-83 : 76

Pseudidotheidae Ohlin

Pseudidotheidae Ohlin, 1901: 274–276 .—Stebbing, 1905: 43.—

Barnard, 1920: 381.— Nordenstam, 1933: 112–113.— Hale, 1946:

168.— Sheppard, 1957: 173–174.— Poore, 2001: 227. Pseudidotheinae.— Wägele, 1989: 137–138.— Wägele, 1991: 80-81.

Diagnosis. Body strongly vaulted. Head and pereonite 1 fused. Pereonite 4 of similar length to pereonite 3. All pleonites fused into pleotelson. Body variously tuberculate or spinose; pleotelson without dorsolateral ridges ending in mediodorsal posterior spine, never with posterior dorsolateral pair of strong spines; limbs and most of surface covered with fine setae that trap sediment. Dorsal coxal plates 2–7 obsolete, bases of pereopods exposed. Mouthparts and pereopod 1 visible in lateral view. Eyes well developed. Antenna 2 flagellum of 2 or 3 articles plus distal claw. Pereopod 1 a gnathopod, pereopods 2 and 3 differentiated from ambulatory pereopods 4–7. Pereopod 1 dactylus evenly curved along anterior margin, evenly tapering. Pereopods 2 and 3 with propodus able to close on carpus, articles broad and with posterior robust setae; with prominent dactylus, unguis short. Pereopods 4–7 similar and ambulatory. Pereopods of males without dense mat of fine setae. Uropodal exopod (smaller ramus) tapering (with terminal setae only), more than half as long as endopod. Oostegites 1–4 functional, not supported by coxal lobes; oostegite 5 present or absent. Penes fused as a single penial plate, apically simple or barely slit. Pleopod 1 peduncle more elongate than on other pleopods; with marginal setae on rami longer than or equal to length of rami. Pleopod 1 exopod of male thickened and with groove on posterior face, with few simple setae along straight lateral margin; with groove on posterior face of exopod ending on tapering distolateral apical extension. Pleopod 2 of male with appendix masculina about as long as endopod, basally less than half width of endopod.

Remarks. The diagnosis is rephrased from Poore (2001) to better define limb differentiation. We note that the body is covered with fine setae, not illustrated in the new species and indicated or mentioned only in passing for other species by Hurley (1957) and Brandt and Wägele (1990). Such setation is not a typical valviferan characteristic. Poore (2001) defined the family as lacking oostegites on pereopod 5; this is true of three species but not of P. scutata . The presence of a fifth pair of oostegites in one species is anomalous among arcturoid families. It is seen elsewhere only in Austrarcturellidae Poore and Bardsley, 1992 where oostegites 5 are vestigial and act as egg guides rather than as part of the marsupium.

Wägele (1989) considered Arcturides a family member but Poore (2001) erected a separate family for this genus.