Oxychilus (Drouetia) viridescens (Gastropoda: Pulmonata: Oxychilidae), a new species from Santa Maria, Açores, and a review of the subgenus.

Oxychilus (Drouetia) viridescens n.sp. is described from Santa Maria Island, Açores. It is conchologically similar to the sympatric Oxychilus (Drouetia) brincki Riedel, 1964, from which it is distinguished by the greenish coloration, the flatter spire and the slightly smaller number of whorls. Anatomically, the new species differs from all consubgenerics by the genital morphology: the penis is very thin, the distal half is wrapped in a very thick penial sheath; the epiphallus has two distinct portions, the proximal one attached to the edge of the penial sheath, the distal one attached to a constriction near mid-length of the penis; the atrial end of the vagina has a spongy, glandular appearance. A detailed morphological and anatomical comparison of the new species with the non-umbilicated Oxychilus species of Santa Maria is presented. The species of Drouetia are reviewed and an identification key is provided.