Demodex neomydis sp. n. from the Mediterranean water shrew, Neomys anomalus, is described as a new species in all developmental stages. This demodecid is classified as a member of the genus Demodex Owen, 1843, but shows several morphological characters described in Soricidex dimorphus Bukva, 1982 and which are absent or very infrequent in other known Demodex species, viz., in the adult stage, a pair of shelf-like lamellae on the dorsum of the podosoma, dorso-lateral extension of the podosoma over the basal part of the gnathosoma, multiple opisthosomal organ in the male, and podosomal position of the vulva in the female. Immature stages of D. neomydis have unusual inflated idiosoma and dorsad deflected gnathosoma. All developmental stages of D. neomydis were found in the lumen of the hair follicles on the host’s muzzle, causing no gross pathological response. On histological level, the main pathological change was distension of infested hair follicles by accumulations of up to a dozen mites, which appear to feed on the epithelial cells of the hair follicle walls.
Sexually dimorphic features of adult males and females of Soricidex dimorphus, a species unparalleled in its dimorphism by any described representative of the family Demodecidae, are compared by scanning electron microscopy. The account of sexual dimorphism in S. dimorphus is preceded by a review of sexually dimorphic features in other demodecid genera. Minute constituents of general morphology of demodecid mites such as claws, solenidia and spines of legs or palps, dorsal podosomal tubercles, and integumental slits and pores, part of which are reported and/or shown in scanning electron micrographs for the first time, are also receiving detailed attention.