Sistemática e taxonomia do gênero Heleobia Stimpson, 1865 (Caenogastropoda, Truncatelloidea) no estado do Rio de Janeiro

Abstract

Heleobia is a genus of freshwater and/or brackish gastropods included in the family Cochliopidae. The genus comprise 104 species, most of them in South America. Although of the diversity and wide distribution, the genus is involved in several taxonomic problems. In this way, the present work has four main objectives: 1- To examine an unspecified species of Heleobia for Ilha Grande, Angra dos Reis, RJ, Brazil; 2- Investigate the species included in the group “australis” of the genus Heleobia based morphological and molecular data; 3- Compare Heleobia davisi and H. robusta through of the integrative taxonomy, and 4 – To present the diversity and distribution of Heleobia spp. in the state of Rio de Janeiro. Carrying out of the work involved the literature review, visited in scientific collections and field surveys in relevant locations. The animals collected were anesthetized with menthol, and fixed in 70º ethanol for dissection, and 96º ethanol for molecular analysis, and it is located in the Mollusks Collection at the State University of Rio de Janeiro. Molecular analysis followed the DNA extraction protocol from phenolchloroform or CTAB (cetyl trimethyl ammonium bromide), and the amplified region of the mitochondrial DNA was Cytochrome Oxidase I. From the photograph of the shells in a stereomicroscope, morphometry was performed in order to investigate sexual dimorphism and morphological variation between species. The analysis of the species not described from Ilha Grande, Angra dos Reis, RJ revealed a distinct penile morphology: a more distal region with a nipple aspect, with a prominent apocrine gland on its concave side, in addition to presenting marked sexual dimorphism in the shell morphometry, and distance genetics of 4% for the closest species, Heleobia parchappii. The species included in the “australis” group are similar in morphological aspects, like observed in the literature, and also in molecular ones, suggesting that it is a single biological entity. The comparison between H. davisi and H. robusta revealed great similarity in the morphology of the shell, the verge, the radula and in the molecular analysis, indicating that H. robusta is synonymous with H. davisi. In addition, the phylogenetic analysis showed a proximity of the populations studied with H. piscium in a clade separate from the other species of Heleobia analyzed, indicating a probable distinct genus.The current diversity of Heleobia in the state of Rio de Janeiro is composed of six species: H. australis, H. parchappii, H. davisi, Heleobia sp. 1, Heleobia sp. 2 and Heleobia sp. 3, distributed in eight of the nine Hydrographic Regions (RH), concentrated in RH VI: Lagos São João Hydrographic Region. Thus, the use of morphological and molecular tools proved to be appropriate to investigate the taxonomic issues of Heleobia. The work contributed to the knowledge about this genus, with new data for the Brazilian species. In addition, it can used as a subsidy for ecological studies and conservation.