*crassicornis (Reuter & Reuter, 1880)
Anurida tullbergi resembles the more common Anurida maritima. Both species are bluish black in colour, have eyes with 5+5 ocelli and lack a furca and empodium on the foot (Fig. 1). However, the post-antennal organ (PAO) of Anurida tullbergi is elliptical with up to 30 vesicles (often asymmetrical on the same specimen - see Figs. 2, 3) (the PAO of Anurida maritima is small and circular with up to 11 vesicles). The largest specimen Steven has seen was 2.5 mm in length from a population collected from a sewage treatment works in London, a habitat in which Anurida tullbergi can reach very high population densities. Most inland records are indeed from sewage works although Anurida tullbergi is also found in the littoral zone and in waterside detritus, particularly if there is a saline influence. At present, there are no records from Wales.