New malacological records for the province of León (N.W. Spain) and percentages of infestation by trematoda.

Abstract

The province of León is situated in the northwestern part of Spain. According to the work “Mapas provinciales de suelos de León” (Provincial soil maps of León) carried out by the National Institute for Agrarian Research (Madrid, 1973), León is considered to be divided into 5 natural regions: Mountain, Transition, Central, El Bierzo and La Cabrera. Roughly speaking, the first 3 correspond to the upper, mid and lower valleys of the rivers of the Douro basin respectively. The material discussed was collected in the period 1972-1975 at ca. 350 localities; the species forming the subject of this study were found generally in a few places only. A total of 761 molluscs was examined for parasites. The following species of Helicidae (Gastropoda, Pulmonata), identified with the assistance of the Rijksmuseum van Natuurlijke Historie(Leiden, Holland), were recorded for the first time in the province.