Untangling the defiant taxonomy of Physaloptera (Nematoda: Chromadorea: Spirurida: Physalopteridae) parasitic in reptiles: an integrative approach on the enigmatic P. retusa suggests cryptic speciation

Abstract

Background: Although Physaloptera retusa is one of the most widespread species infecting reptiles in the Americas, numerous taxonomic problems and little genetic data are associated with it. To clarify the taxonomy of this species, we used an integrative approach; (2) Methods: Physaloptera retusa infecting Erythrolamprus typhlus (snake) from Pantanal wetlands, Brazil, was morphologi-cally and genetically characterised (18S and 28S rDNA; COI mtDNA), and compared with con-specific sequences available in GenBank, from parasites of Tupinambis teguixin (lizard), using species delimitation methods. Type specimens of P. liophis were revaluated given its morpho-logical similarities with P. retusa; (3) Results: Morphology of the present specimens was equal to that of P. retusa, in which the only difference from P. liophis was the relative position of the vulva. Species delimitation methods were more accurate for COI dataset; all of them (except ABGD) indicated interspecificity among P. retusa sequences. However, lack of morphological data or voucher material, associated with the deposited sequences, prevented more assertive conclu-sions; (4) Conclusions: The present results highlight the importance of a clear association between genetic data and morphology of the isolation source, or at least its adequate vouchering. More-over, P. retusa may represent a species complex in cryptic speciation, since it is widespread and has low host specificity.