Australian Isopoda: Families

S.J. Keable, G.C.B. Poore & G.D.F. Wilson

Idoteidae Samouelle, 1819

Idoteadae Samouelle, 1819: 106.

Idoteidae. -Poore, 2001b: 220.

Description. Body. Body shape without loss or gross modification of appendages on one side of the body; in dorsal view without peduncular articles of antenna 1 or 2 contiguous with coxal margins, tapering posteriorly; in lateral view straight, more or less flattened or semicylindrical, or strongly vaulted. Body surface smooth or slightly sculptured, or variously spinose or rugose.

Head. Head not capable of lateral rotation (laterally encompassed, abutting or fused to pereonite 1); free from pereonite 1, or fused to pereonite 1 (Crabyzos, Lyidotea only); more or less semi-cylindrical. Eyes well developed, or reduced or lost. Antenna 1 inserting on head anteriorly and/or dorsally to antenna 2, minute or well developed; not as follows: reduced to 2 articles with second article expanded and scalloped. Antenna 2 well developed; flagellum multiarticulate, or clavate (usually with minute terminal article(s)). Mouthparts not forming suctorial cone or proboscis. Mandible not projecting anteriorly and together forceps-like; palp absent. Maxilliped epipod as long as or longer than wide.

Pereon. Pereonite 4 of similar length to pereonite 3. Pereonites 6-7 pereonite 7 distinct dorsally, free. Coxae extending ventrally and laterally to overhang the coxa-basis articulation of the pereopods, or not extending ventrally and laterally to overhang the coxa-basis articulation of the pereopods; 2-7 more or less ventrally expanded over bases of pereopods (coxal plates often very reduced), or 5-7 expanded over bases of pereopods and tergites marginal on pereonites 2-4 (Synidotea only), or 2-7 obsolete and with expanded marginal tergites (Synischia only). Oostegites 1-5 functional, or 1-4 functional, 5 absent (Synidotea only). Pereopods 6-7 pairs readily apparent; 1-3 or 1-7 not prehensile; 1 slightly differentiated from 2 (propodus broader than in 2); with dense fur of fine setae in males. Pereopod 1 propodal palm without proximal tooth (palm more or less continuous with that of carpus). Pereopods 2-4 with irregular fine setae and marginal robust setae; 2-4 dactylus prominent, unguis short. Pereopod 4 similar to pereopod 3. Pereopods 5-7 without flattened setose articles andor dactyls modified or absent. Penes fused basally as a penial plate but divided over most of length, or fused as a single penial plate (Synidotea only), or paired, elongate (Lyidotea only).

Pleon / Pleotelson. Pleonites and pleotelson with pleonites 3-5 and pleotelson fused, pleonites 1-2 articulating, or pleonites 2-5 and pleotelson fused, pleonite 1 articulating, or pleonites 1-5 and pleotelson fused (other pleonites sometimes indicated laterally or dorsally). Pleopods 5 pairs present. Pleopod 1 peduncle subequal to peduncle on pleopods 2-5; marginal setae on rami much shorter than length of rami; exopod of males laminar, lateral excavation absent. Pleopod 2 of males not consisting of an enlarged peduncle with a geniculate endopod and a small muscular exopod; appendix masculina about as long as endopod, basally less than half width of endopod. Uropods positioned proximally on pleotelson; folded ventrally below pleotelson, forming operculum enclosing pleopodal chamber. Peduncle not forming an elongate clavate article with rami reduced or absent. Endopod not claw-like (acute and recurved) andor posteroventral in position. Exopod present, or absent (usually); not folded dorsally over pleotelson, ovate, fringed with setae, more than half as long as endopod (if present).

Distribution and generic composition. See Kensley et al. (1996).

Cite this publication as: 'S.J. Keable, G.C.B. Poore & G.D.F. Wilson (2002 onwards). 'Australian Isopoda: Families. Version: 2 October 2002.'.