Convergent evolution: A new subfamily for bipaliin-like Chilean land planarians (platyhelminthes)

摘要

The monotypic genus of land planarians Timyma (Rhynchodeminae, Geoplanidae) has been suggested to be a relict that could reflect a pre-Tertiary Antarctic connection between South America and Australia and New Zealand. Two species belonging to this genus, Timyma juliae E. M. Froehlich, 1978 and Timyma olmuensis Almeida & Carbayo sp. n., are (re)described herein. Both species present ventral testes and a semilunate headplate, the same as the members of the Oriental subfamily Bipaliinae. Timyma olmuensis Almeida & Carbayo sp. n. is studied by means of an integrative approach. Two nuclear gene fragments (28S, EF) and a mitochondrial gene fragment (COI) were sequenced. Phylogenetic analyses pointed out that Timyma is the sister-group of the Neotropical Geoplaninae and is phylogenetically distant from Bipaliinae, contradicting the hypothesis of Timyma as a South American relict of a Gondwanan taxon. These results indicate that the headplate evolved independently in Timyma and Bipaliinae. Morphological data reinforce this view. Accordingly, Timyminae subfam. n. is proposed for Timyma and a new diagnosis for the genus is proposed.