The planorbid snail Biomphalaria edisoni n. sp. is described from morphological and molecular characters, based on specimens collected at two localities in Colombia. The new species has the typical features of the genus, as well as the following characteristics: vaginal pouch, numerous prostatic diverticula arranged in racemes, penis sheath/prepuce ratio of approximately 2 and a penial complex half the length of the cephalic portion of the female duct. These elements differentiate it from B. kuhniana, which was also present in one of the localities, and also from B. prona, B. helophila and B. nicaraguana, with which it has greater morphological similarities. Phylogenetic analysis of the nucleotide sequences of the internal spacers of the ribosomal DNA transcript (ITS1, ITS2) of B. edisoni n. sp. and 14 neotropical Biomphalaria species indicates that the former belongs to the monophyletic group including B. prona and B. sp. from Cuba. The genetic distances within this monophyletic group are however great enough for B. edisoni n. sp. to be regarded as a separate species. Thus morphology, phylogenetic tree topology and genetic distances all support the recognition of B. edisoni as a new species. MATERIAL AND METHODS Collection sites Material was collected from two sites. The Cali population was collected in February 2000 in the artificial lakes of the University of Valle del Cauca in Cali (3822 0 N, 76831 0 W), water temperature was 288C and pH 8.4. The Puente Iglesias population was collected on the west side of the El Sapo stream, 2 km upstream of the mouth of the Cauca river, in June-July 2001 at the Inspeccio´n Puente Iglesias, in the municipality of Fredonia (5848 0 N, 75840 0 W); they were found in fine sediments at depths of less than 5 cm in slow-flowing water with a temperature of 31-358C and pH 8.4. Morphological study Snails were transported live to the Medical Malacology Laboratory (MML) of PECET, where they were maintained in aquaria with artificially aerated dechlorinated water and a sterile mud substrate. They were fed on fresh lettuce. After 2 days of acclimatization, all the specimens were placed individually in vials containing dechlorinated water. These were exposed to a light source for 8 h as a stimulus to provoke the emission of cercariae. The snails that voided cercariae were then counted and installed in a specially conditioned aquarium. This assay was
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