Nototanaidae Sieg 1976

Family NOTOTANAIDAE Sieg, 1976

Genus Nototanais Richardson, 1906 Nototanais dimorphus (Beddard, 1886) Figs 9–10

Paratanais dimorphus Beddard, 1886a, p.119; 1886b, pp.130–132. pl. XVIII, figs. 1–8.

Nototanais dimorphus Richardson, 1906, p.187; 1908, pp.1–3, Fig. 1 Nototanais australis Richardson, 1908, p. 1, fig. 1.

Nototanais australis Vanhöffen, 1914, p. 470.

Notototanais magellanicus Monod, 1925, p. 296; 1926, p. 10, fig. 1. Nototanais dimorphus Shiino, 1970, PP. 85-91, figs. 6-10. Nototanais australis Lang, 1973, p. 222.

Nototanais dimorphus Sieg, 1980b, pp.54-60, figs. 6, 8–9 and 11.

Material examined: 1 female, 51º04.08ʹS 74º08.49ʹW, rocky bottom, 5–15 m, 27 January 2010; 18 neuters and females, 50º50.74ʹS 74º01.58ʹW, rocky bottom, 5–15 m, 28 January 2010; 1 female, 48º40.48ʹS 74º27.46ʹW, rocks with red algae, 5–15 m, 22 March 2010. All coll. R. Barría, E. Newcombe, M. Hune, T. Césped. M. Palacios, C. Cárdenas, A. Montiel, M. Hune and C. Aldea.

Nototanais dimorphus is, as its specific name suggests, a strongly dimorphic species. Only juveniles and females were found in BONP. Consequently, the diagnosis proposed herein obviates sexual dimorphic characters, but is valid for both genders. Drawings of the specimens from BONP are included to complete previous descriptions (i.e. Beddard, 1886; Shiino, 1970) and revisions (Sieg, 1980b).

Diagnosis: Nototanais with body relatively narrow; maxillular palp bearing two long, terminal setae; pereopods 4 to 6 merus bearing long, straight, terminal spines.

Remarks: Body length of specimens from BONP: 2.2–2.7 mm. In our specimens, the spines on the carpus of pereopods 4 to 6 are long and straight (Figs 10 D, F), reaching (at least two of them) half of the length of the propodus. Although Shiino (1970) illustrates these spines as being significantly shorter, our specimens agree with Sieg (1980b), who considered them as a diagnostic character that differentiates N. dimorphus from N. antarcticus (with short, finely plumose spines). Shiino (1970) observed three spines on the tip of the propodus of pereopod 6, while other authors made no special mention of this feature; our specimens have between four and seven of these spines (Figs 10 F).

This species is known from the southern hemisphere, in sub-Antarctic islands (Kerguelen, Macquarie, Adelie and Magellanic Islands: Sieg, 1980b) and Antarctic islands (Greenwich Island: Shiino, 1970; King George Island: Błażewicz-Paszkowycz & Jazdzewski, 1996), in shallow waters between 4 and 20 m depth (Sieg, 1986b).

Monod (1926) described Notototanais magellanicus from the Magellanic region, distinguishing it from N. dimorphus on the conformation of the male cheliped. Sieg (1980b) examined the females collected by Monod, and considered the species to be conspecific. As Sieg could not confirm or otherwise the distinction of the male (the specimen being lost), and as the present material has a longer, narrower cephalothorax and longer pereonites 1 to 3 than N. dimorphus as described by Sieg, it remains possible that N. magellanicus is a distinct species, in which case the present material is likely to belong to that taxon. The recovery of further male material is required to confirm this; however, a number of cryptic species within N. dimorphus sensu Sieg (1980b) is easier to accept than a very widespread single species with little dispersive capability.