Australian Isopoda: Families

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

Antarcturidae Poore, 2001

Antarcturidae Poore, 2001b: 224.

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; in lateral view flexed between pereonites 4 and 5. Body surface strongly spinose with at least dorsal and dorsolateral pairs of spines, often dominated by pair near end of pleotelson.

Head. Head not capable of lateral rotation (laterally encompassed, abutting or fused to pereonite 1); fused to pereonite 1. 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 of 2-3 articles plus distal claw. Mouthparts not forming suctorial cone or proboscis; with pereopod 1 visible in lateral view. Mandible not projecting anteriorly and together forceps-like; palp absent.

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 obsolete, bases of pereopods exposed. Oostegites 1-4 functional, 5 absent; 1-4 supported by mesial coxal lobes. Pereopods 6-7 pairs readily apparent; 1-3 or 1-7 not prehensile; 1 a gnathopod, 2-4 elongated, differentiated from ambulatory 5-7; without dense fur of fine setae in males. Pereopod 1 dactylus evenly curved along anterior margin, evenly tapering. Pereopods 2-4 with paired long setae along posterior margins evenly and well developed; 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 as a single penial plate; penial plate apically simple or barely slit.

Pleon / Pleotelson. Pleonites and pleotelson with pleonites 1-5 and pleotelson fused. Pleopods 5 pairs present. Pleopod 1 peduncle longer than peduncle on pleopods 2-5; marginal setae on rami longer than, or equal to, length of rami; exopod of males thickened and with groove on posterior face, with groove on posterior face ending distolaterally or laterally on simple margin, lateral margin straight, with few simple setae. 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. Pleotelson without dorsolateral ridges ending in mediodorsal posterior spine. 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; not folded dorsally over pleotelson, tapering, with terminal setae only, more than half as long as endopod (when present).

Distribution and generic composition. Includes most of the species from Antarctica previously treated as members of the Arcturidae. The family is most diverse in the Southern Ocean and the dominant valviferan family in the deep sea of both hemispheres (Poore, 2001b). See Kensley et al. (1996) but note that Poore (2001b) considers the family to contain the following genera with numbers of included species in parentheses: Abyssarcturus Kussakin and Vasina, 1995 (1); Acantharcturus Schultz, 1981 (1); Antarcturus zur Strassen, 1902 (26); Caecarcturus Schultz, 1981 (1); Chaetarcturus Brandt, 1990 (20); Cylindrarcturus Schultz, 1981 (2); Fissarcturus Brandt, 1990 (9); Globarcturus Kussakin and Vasina, 1994 (1); Litarcturus Brandt, 1990 (7); Mixarcturus Brandt, 1990 (3); Oxyarcturus Brandt, 1990 (3); Pleuroprion zur Strassen, 1903 (11); Spinarcturus Kensley, 1978b (1); Thermoarcturus Paul and Menzies, 1971 (1); Tuberarcturus Brandt, 1990 (3) (90 species in all).

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