Chydorus sphaericus (O. F. Müller, 1785)

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 : 1269

Chydorus sphaericus (O. F. Müller, 1785)

This species is supposedly cosmopolitan ( Smirnov 1996) but is most probably a species group. It has been recorded from the Falkland Islands ( Vávra 1900; Ekman 1905) and from several of the subantarctic islands ( Frey 1993). Dartnall and Heywood (1980) recorded C. sphaericoides Sars, 1909 from the Falklands, a species name that Frey (1993) ascribed to C. sphaericus , whereas Smirnov (1996) believes it to be a synonym of C. patagonicus Ekman, 1900 , a species recently reported from Macquarie Island ( Dartnall et al. 2005). Our specimens are most probably C. sphaericus as suggested by the variable labral plate which in some specimens has an elongated and rounded tip, while in those from the Brown Pond are bent posteriorly. The post-abdomen is short and broad with 9–11 denticles, though two specimens from Moody Brook has 13 denticles. Ekman (1905) noted several similarities between the females of C. sphaericus and C. patagonicus . We did not find any males in the samples that would enable us to verify the diagnosis. Both C. sphaericoides and C. sphaericus have been reported from the Falkland Islands by Smith and Sayers (1971).