Polyploidy in Bulinid Snails, with Emphasis on Bulinus truncatus/tropicus Complex (Planorbidae: Pulmonate Mollusks) from Various Localities in Ethiopia

TLDR: Data is provided on the occurrence and distribution of various ploidy levels of B. truncatus/tropicus complex in Ethiopia based on meiotic bivalent chromosome counts and the result showed that diploid species are mainly associated with low altitude, tetraploid with both low and medium altitudes whereas hexaploids and octoploids with high altitudes.

Abstract: Freshwater snails of the genus Bulinus, mostly Bulinus truncatus/tropicus complex occur in Ethiopia in various ploidy levels (diploid, tetraploid, hexaploid and octoploid) which are otherwise rare in other animal phyla. This study provides data on the occurrence and distribution of various ploidy levels of B. truncatus/tropicus complex in Ethiopia based on meiotic bivalent chromosome counts. Emphasis was made on the role of shell morphology and chromosome number in species identification of B.truncatus /tropicus group. Specimens were collected from fourteen different localities in Ethiopia. Chromosome preparation was made from gonad tissue (ovotestis). The result showed that diploid species are mainly associated with low altitude, tetraploid with both low and medium altitudes whereas hexaploids and octoploids with high altitudes. Unexpected result was found in Lake Hora, where both diploid and tetraploid populations were occurring together in the same microhabitat which is in contrary to suggestions of some authors that two cytotypes of Bulinus truncatus/ tropicus complex do not occur in the same water body in Ethiopia. It was recommended that thorough investigation of each water body where snails are occurring, should be undertaken using cytological and molecular approaches and that the possibility of hexaploid Bulinussnails as potential host of human schistosome parasites in the highland of Ethiopia.