Integrative taxonomy: combining molecular and morphological characteristics to identify Lymnaea (Galba) cubensis, intermediate host of Fasciola hepatica

Taxonomia integrativa: combinando características moleculares e morfológicas para identificar Lymnaea (Galba) cubensis, hospedeiro intermediário de Fasciola hepatica

Abstract

Despite the epidemiological importance of the Lymnaeidae family regarding transmission of Fasciola hepatica, knowledge about the diversity and distribution of these molluscs and the role of each species in the expansion of fasciolosis remains sparse. Classical morphological (n=10) identification was performed in lymneids from Lagoa Santa, a municipality in the state of Minas Gerais, Brazil, along with molecular and phylogenetic analysis (n=05) based on the partial nucleotide sequences of the mitochondrial cytochrome c oxidase subunit I gene (COI mtDNA) and ribosomal internal transcribed spacer II (ITS-2 rDNA). The shell morphology made it possible to distinguish the lymneids of Lagoa Santa from Pseudosuccinea columella. Differences found in the penile complex and prostate shape allowed this species to be distinguished from Galba truncatula. However, the homogeneity of reproductive tract characteristics among Lymnaea (Galba) cubensis, L. viator and L. neotropica confirmed that these characteristics show low taxonomic reliability for identifying cryptic species. Genetic divergence analysis for the COI mtDNA gene and ITS-2 region of rDNA revealed greater similarity to Lymnaea (Galba) cubensis. Thus, correct species differentiation is important for monitoring the epidemiological risk of fasciolosis in the state of Minas Gerais, where cases of the disease have increased over recent years.

Keywords:
Intermediate host; Trematoda; COI; ITS-2; morphology