First record of Parvidrilidae (Annelida, Oligochaeta) in Europe with a description of a new species (Parvidrilus spelaeus sp. nov.) and comments on the family and its phyletic relationships

Abstract

A new species of the oligochaete family Parvidrilidae Erséus, 1999 is described from several subterranean waterbodies of southern Europe. A comparison with the type species suggests that the so called ‘genital body’ and ‘copulatory organ’ of the latter can be interpreted as the atrium and spermathecae, respectively. A critical analysis of the most important diagnostic features known is made to increase understanding of the real position of the Parvidrilidae in a natural system within the Oligochaeta. The parvidrilids seem to be closely related to the Phreodrilidae. Waiting for the results of molecular and ultrastructural analyses, and considering the dorsal crotchets ‘buried’ in the body wall as an autapomorphy for the phreodrilids, the rank of family for the parvidrilids is maintained on the basis of the three following autapomorphies: the location of the setae in a marked posterior position within the segments; the lateral development of the clitellum, with large clitellar cells in relation to the body diameter; the singular glandular pouches present in the mid-dorsal line of the mesosomial segments.