Balea heydeni von Maltzan, 1881 (Pulmonata: Clausiliidae): an overlooked but widely distributed European species

Balea (Balea) heydeni was originally described by von Maltzan (1881) on the basis of material from Portugal. Since that time this species has either been completely overlooked or regarded as a synonym of Balea (B.) perversa. However, the two species may occur sympatrically, clearly demonstrating their specific distinctness, a conclusion also supported by molecular phylogenetic data. Comparative descriptions of the two species are given here, together with illustrations of a newly designated neotype for
Balea (B.) perversa and a lectotype of Balea (B.) heydeni. It is hoped that this taxonomic clarification will stimulate further
research. The distribution of B. heydeni is as yet poorly known but it occurs on the Azores and the Madeiran archipelago (Porto Santo),from where it has for many years been reported incorrectly as B. (B.) perversa. Elsewhere B. heydeni has been recognized from Portugal, Spain, France, Belgium, The Netherlands, Denmark, Britain and Ireland.