Biomphalaria prona (Gastropoda: Planorbidae): a morphological and biochemical study

Abstract

Two samples of Biomphalaria prona (Martens, 1873) from Lake Valencia (type locality) and seven from other Venezuelan localities were studied morphologically (shell and reproductive system) and biochemically (allozyme electrophoresis). In spite of marked differences in shell characters, all of them proved indistinguishable under the anatomic and biochemical criteria. So far B. prona has been considered an endemic species, restricted to Lake Valencia. It is now demonstrated that the extralacustrine populations refered to Biomphalaria havanensis (Pfeiffer, 1839) by several authors correspond in shell characters to an extreme variant of B. prona from the Lake and really belong to the last*mentioned species. They may be regarded as the result of a process of directional selection favoring a shell phenotype other than those making up the modal class in the Lake

Genetic variability and identification of the intermediate snail hosts of Schistosoma mansoni

“…The average percentage of shared bands between each pair from the same locality was 74.5% and between all possilble pairs from different localities was 43%. These results agree with those obtained for B. glabrata in Puerto Rico and in B. prona using isoenzymes (Mulvey & Vrijenhoek 1982, Mulvey et al 1988, Paraense et al 1992, or for Bulinus snails using RAPD analysis (Langand et al 1993). The high variability of B. glabrata (90%) is in contrast with that of Schistosoma (10%).…”

Characterization of Biomphalaria orbignyi, Biomphalaria peregrina and Biomphalaria oligoza by polymerase chain reaction and restriction enzyme digestion of the internal transcribed spacer region of the RNA ribosomal gene

“…The first authors observed that in spite of these differences, similar profiles were generated for both populations. This molecular data provide support to this group suggested by Paraense et al (1992) and revealed to be an useful tool for studying species with great phenotypic plasticity. After testing several enzymes, Vidigal et al (2000) showed that specific separation between Brazilian populations of B. oligoza and B. peregrina became difficult due to the similarity of the profiles generated by this technique.…”

“…Also using this methodology, Spatz et al (1999) proposed the B. tenagophila complex due to the morphological and molecular similarities among B. t. tenagophila, B. t. guaibensis, and B. occidentalis. Caldeira et al (2000) also using PCR-RFLP studied B. prona populations from Lake Valencia (Venezuela) and outside this lake, in which morphological differences had been previously described by Paraense et al (1992). The first authors observed that in spite of these differences, similar profiles were generated for both populations.…”

Identification of Biomphalaria havanensis and Biomphalaria obstructa populations from Cuba using polymerase chain reaction and restriction fragment length polymorphism of the ribosomal RNA intergenic spacer

“…In spite of the important questions on B. obstructa (Yong 1998) and the type locality of B. havanensis (Yong et al 1997), in the present work, the Cuban snail populations were identified in accordance with the classical morphological systematics adopted by Paraense, which has produced the most complete description of the majority of the Neotropical Biomphalaria species (Paraense 1975a,b, 1990, 1996, Paraense et al 1992.…”