Observations on the nematode fauna of terrestrial molluscs of the Sofia area (Bulgaria) and the Crimea peninsula (Ukraine)

Short surveys on the nematode fauna of terrestrial molluscs in Sofia, Bulgaria and Crimea, Ukraine were performed. The composition of nematode fauna was compared with data from the literature and in our records of nematode fauna from different regions of continental Europe and the British isles. Two nematode species, Angiostoma dentiferum Mengert, 1953 and Agfa tauricus Korol & Spiridonov, 1991 were found parasitising three and four, respectively, out of a total of 23 host species. The composition of nematode fauna was similar in both surveys, though the dominant nematode species in each region were different, with A. dentiferum in Bulgaria and A. tauricus in Crimea. Both morphological and molecular methods have demonstrated the complete identity of material from the two regions. The re-examination of our own material of A. dentiferum from Belgium has confirmed its similarity to that from Bulgaria and Crimea by molecular characteristics, and slightest morphological differences. Morphologically, A. dentiferum from Bulgaria, Crimea and Belgium corresponds well with its original description from Germany (Mengert, 1953). We assume that the re-description of A. dentiferum by Morand & Spiridonov, 1989, based on the material from France, is that of a closely related but different species, which is distinguished by presence vs absence of lateral alae and shorter spicules. Although the data on the distribution of parasitic nematodes of terrestrial molluscs in Europe are inconsistent, it seems that A. tauricus tends to be present in the south-east of Europe and absent from more northern territories where it is replaced by A. flexilis though the host range for both species is similar