New data on Theba subdentata helicella (Wood, 1828) (Gastropoda, Helicidae) in Almería (SE Spain)

The distribution of Theba subdentata helicella (Wood, 1828) in the Eastern part of the Almería Bay is studied. This paper confirms the existence of rich populations of T. s. helicella inhabiting the lowlands close to the sea, never reaching the surrounding mountains. Information on the habitat, shell and genital system variability is provided. The shells show a characteristically depressed and sharply keeled shape, and are usually white or with a light brown to orange spiral band near the carina in all populations except in Amoladeras watercourse (inside the Cabo de Gata-Níjar Natural Park). In this locality there is a gradation from the typical form to almost globular specimens with a very slight keel, nearly wanting, only visible on the last half of the body whorl near the aperture, similar to T. s. dehnei (Rossmässler, 1846) from Morocco. These shells show basal bands or blotches that remind those of Theba pisana pisana (O.F. Müller, 1774) or T. s. dehnei. The genital system of the Amoladeras population is compared with those described for T. s. helicella y T. s. dehnei from Morocco, confirming that it shares more characters with the first subespecies. A discriminant function analysis of shells characters measurements of two populations of T. s. helicella and T. p. pisana allowed to discard the hypotesis of an hybrid origin of the globose specimens. Data on the presence and habitat of other gastropod species living with T. s. helicella in the study area are provided