Macrothrix hirsuticornis Norman and Brady, 1867

Dartnall, Herbert J. G. & Hollwedel, Werner, 2007, A limnological reconnaissance of the Falkland Islands; with particular reference to the waterfleas (Arthropoda: Anomopoda), Journal of Natural History 41 (21 - 24), pp. 1259-1300 : 1273

Macrothrix hirsuticornis Norman and Brady, 1867

Recorded from the Falkland Islands as M. ciliata by Vávra (1900), and M. propinqua by Ekman (1905) and Sars (1909). We regularly encountered juvenile and fertile females. Our specimens averaged 0.62 mm, a similar size to that reported by Vávra but only half that of specimens from German islands in the southern North Sea ( Hollwedel and Scharf 1988). Ekman’s (1905) specimen range was 0.85–0.92 mm. Sars (1909) points out that his M. propinqua (1.14 mm) from South Georgia has less curved antennulae which are ‘‘less densely hirsute’’, with a smaller ocellus nearer to the tip of the rostral projection. Both characteristics are found in our specimens ( Figure 19 ). Smirnov (1992) states that no other distinctive differences are known and claims that those ‘‘features correspond with the present-day understanding of M. hirsuticornis ’’. The late David Frey considered all Antarctic identifications of Macrothrix hirsuticornis to be dubious as this is a boreal northern hemisphere species. A. A. Kotov (personal communication) thinks that the Falkland Island Macrothrix is Vávra’s M. ciliata , but it must be checked against Ekman’s Patagonian species M. oviformis to see which has priority as both species were described in 1900.

Figures

Figure 19. Macrothrix hirsuticornis, female, antennulae.