Austronanus gelidus, Just, Jean & Wilson, George D. F., 2006

Just, Jean & Wilson, George D. F., 2006, Revision of Southern Hemisphere Austronanus Hodgson, 1910, with two new genera and five new species of Paramunnidae (Crustacea: Isopoda: Asellota), Zootaxa 1111, pp. 21-58 : 41-43

Austronanus gelidus sp. nov.

( Fig. 10 )

Etymology. The species name is Latin for icy, referring to the Antarctic habitat of this species.

Material examined

Holotype. Ψ, 1.31 mm, Antarctica , Davis Station, 68°38'S 77°48'E, M. Tucker, 6 January 1982, NMV J4773.

Description. Body width 0.46 length in female, widest at pereonite 2 or 3. Head length 0.73 width; length posterior to eyestalks 1.0 anterior length. Frontal margin lobe length 0.37 head length; apex bluntly angular in dorsal view, margin adjacent to apex convex, not sinuous. Eyestalks lateral apex somewhat flattened, long axis angling forward at approximately 45°.

Pereonite lateral margin 1–4 linear, 5–7 rounded. Pereonite 5 in dorsal view distinctly narrower than pereonites 4 and 6. Pereonite lateral margin 7 finely denticulate.

Pleon length 1.0 width in female; pleotelson proximal margin length shorter than lateral margin length. Pleonite 1 width 1.0 distance between uropods, length 0.2 width.

Pleotelson laterally angular anteriorly, lateral margins straight sided; proximal margin forming 60° angle with medial axis of pleon; lateral margins denticulate, with 12 denticles (right side only, left side damaged in holotype), increasing in size posteriorly; posterior margin forming 100° angle.

Antennula articles 1 and 2 combined extending beyond eyestalk apex; article 1 length and width subequal to 2, tubular; 5 and 6 of subequal length, longer than articles 3 and 4.

Antenna article 2 lateral margin with two spines (proximal spine smaller); article 3 in ventral view tubular, width 0.41 length, broadening slightly on crenate lateral margin, crenate flange low and thin, lacking subdivisions; article 5 distinctly longer than article 4; flagellum with 7 articles, proximal article 1.4 length of second articles.

Pereopod I basis with crenate ridge on anterior margin, length 3.0 width; ischium anterodistal margin with crenate ridge; merus with 2 spines on anterior margin, 1 spine on posterior margin; carpus distal width 0.9 posterior margin length, with 2 denticles proximal to robust setae, 2 denticles between robust setae, one denticle distal to robust setae; propodus narrowing distally to insertion of dactylus, with 1 robust seta, with fine crenate ridge. Pereopod II basis with crenate ridge. Pereopods V and VI coxae lateral margin smooth, VII with single denticle.

Female operculum distal part tapering with concave distolateral margins, width 0.90 length.

Uropods on lateral margin of pleotelson.

Size. Largest female 1.31 mm.

Distribution. Known only from the type locality.

Remarks. Austronanus gelidus sp. nov. differs from other species with evenly convex lateral margins of the head, as discussed above under A. dubius .

Figures

FIGURE 10. Austronanus gelidus, sp. nov. Holotype, female. a, antenna; au, antennula; cv, ventral view of head; dv, dorsal view; mdp, mandible palp; op, operculum; p 1 ­ 2, pereopod I and II; pe 5 ­ 7, pereonites 5 ­ 7 with coxae; pt, pleotelson; up, uropod. Habitus scale bar: 0.5 mm.