Revision of the genus Albinaria in Crete (Greece): presence of geographically variable monotypic and polytypic species (Gastropoda: Clausiliidae)
The highly diverse genus Albinaria in Crete (Greece) is revised in a comprehensive study on the morphology and distribution of the species. Shell character states were transferred to numerical values to provide a base for reproducible results. Detailed maps for widespread species based on ten thousands of individually measured shells collected at 4850 localities revealed complex spatial gradients in morphological characters, which often varied in various independent directions over area. Combined colour plots were used to see if spatial variations of some genetically independent characters were concordant. Only in two species (A. hippolyti and A. corrugata) narrow hybrid zones between clearly distinct populations were detected. The results suggest that in Crete it is possible and useful to apply the concepts for species and subspecies as established by Mayr (1942) and Wilson & Brown (1953), currently used in many other fields of biodiversity research, in combination with recent knowledge on hybrid zones (Barton & Hewitt 1985). Together with a new species from Pondikonísi Albinaria pondika n. sp., 31 species containing 7 additional subspecies are recognized in Crete and surrounding islands, less than in previous systems in which 37 species were recognized with more than 40 additional subspecies. In the A. cretensis group only five species (A. cretensis, A. tenuicostata, A. sphakiota, A. eburnea and A. sublamellosa) and no additional subspecies were tenable. The morphological diversity is best described verbally, by showing in detail the gradients as they are distributed over area. It would be inefficient and misleading to correlate the highly complex geographical variation in Albinaria with a sophisticated trinominal taxonomic system.