Invertebrate Systematics Invertebrate Systematics Society
Systematics, phylogeny and biogeography

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An integrative taxonomic approach reveals the first marine triclad (Platyhelminthes) trapped in a cave from a semi-arid Neotropical environment

Stella Souza , Marta Riutort , Rodrigo Ferreira , Ana Leal-Zanchet

Abstract

A new genus and species of the suborder Maricola, representing the first marine triclad living in freshwater within a cave, is described. These flatworms show specialized features, such as lack of pigmentation and eyes, indicating their troglobitic condition. Till now, cave dwelling triclads have only been found as representatives of other two triclad lineages. The phylogenetic trees based on the genes 18S rRNA and 28S rRNA show that this new genus and species forms a clade situated in a rather derived position within the Maricola. Combining maximum likelihood and Bayesian analyses along with morphological studies, we do the first integrative description of a marine triclad. The new genus is characterized by a secondary copulatory bursa and ovaries located behind the root of the pharynx. Nevertheless, its assignment to a family of Maricola was a difficult task especially due to the paucity of unique, defining morphological features of many maricolan families. The new species was found in a semi-arid environment that suffered marine transgressions and regressions during the Cretaceous, which may explain the presence of this originally marine species in a freshwater cave. Its restricted distribution and recent impacts detected in its type-locality raise a major concern for its conservation.

IS17062  Accepted 30 September 2017

© CSIRO 2017