Anurida denisi is a dark blue littoral species very similar in general appearance to Anurida maritima. However, Anurida denisi has eyes with 3+3 ocelli (Fig. 1) and highly distinctive mouthparts (Fig. 2). This has led some authors to place it in the genus Gastranurida. The post-antennal organ (PAO) is circular with between 8 and 13 vesicles (Fig. 3); the species does not possess a furca or an empodium on the foot. Several of Bagnall's specimens which I have examined were named Anurida hibernica but this was shown by Lawrence & Goto (1968) to be a junior synonym of Anurida denisi. The species is probably widely-distributed around the coast of Britain and Ireland. It is easy to confuse with Anurida maritima in the field and this is likely to have led to Anurida denisi being under-recorded. The largest specimen I have seen was 1.7 mm in length.
Fig. 1 (above): Anurida denisi collected from Bantry Bay, Ireland in September 1939 by R.S. Bagnall showing the three ocelli in the eye and the post-antennal organ (PAO).(1-3).
Fig. 2 (above): Anurida denisi collected from Howth, Dublin in May 1939 by R.S. Bagnall showing the distinctive tips of the mandibles and maxillae. Ant, anterior; Post, posterior.
Fig. 3 (above): Anurida denisi collected from Bantry Bay, Ireland in September 1939 by R.S. Bagnall showing post-antennal organ (PAO) with ten lobes.
