Estudo citogenético de Leptinaria unilamellata (d´Orbigny, 1835) (Mollusca, Gastropoda, Subulinidae)

Abstract

Pulmonate molluscs have been recognized as interesting models to study hidden biodiversity due to some biological characteristics as low vagility and self-fertilization capacity, besides the historic of species descriptions based solely on the shell. Cytogenetics is used to infer species relationships in several plant and animal taxa. This approach may contribute to the better resolution of the taxonomy within Pulmonata. The present study aimed to establish protocols to cytogenetic studies of terrestrial molluscs testing different target tissues, reagents concentrations and incubation times. We performed a review of the cytogenetic protocols described in the literature for phylum Mollusca and after that; we delineated protocols which were tested in bioassays, using the species Leptinaria unilamellata as experimental model. In the present study we found that L. unilamellata present diploid number of 56 chromosomes, 44 metacentrics e 12 submetacentrics. This result is in accordance with the chromosome numbers described to terrestrial snails from superfamily Achatinoidea, which varies from 2n=44 to 2n=60. Furthermore, with the technique of silver nitrate staining, we found the presence of two sites in the nucleus corresponding to nucleolus organizer regions, or active regions of DNA. The establishment of cytogenetic protocols adequate to terrestrial snails will allow increasing the number of land snail’ species karyomorphologically studied, contributing to the better resolution of the taxonomy and evolution of this group.