Cercyon castaneipennis Vorst, 2009 (Hydrophilidae) new to Britain

摘要

Cercyon castaneipennis Vorst, 2009 (Fig. 6) was recognised by Oscar Vorst as a species distinct from C. obsoletus (Gyllenhal) on the basis of morphological differentiation including elytral coloration, dorsal punctation, shape of the antennal club and structure of the mentum, together with slight differences in the appearance of the aedeagus. The species has a central European distribution extending to the southern part of northern Europe but in recent years has expanded its range to the west. In the Netherlands it is apparently more common than C. obsoletus; all authenticated specimens have been collected since the year 2000 (Vorst, 2009). Consequently, the arrival of the species in Britain has been anticipated (Foster et al., 2014).