Species Diversity and Molecular Characterisation of Baltoplana Karling, 1949 (Platyhelminthes, Rhabdocoela, Schizorhynchia): A Taxonomic Revision, Partial Mitogenome Annotation, and Seven New Species

We present a taxonomic revision, including phylogenetic analyses of the schizorhynch taxon Baltoplana Karling, 1949 (Cheliplanidae). We describe seven new species and provide new morphological data for two known species. Species are mainly distinguished by the morphology and degree of sclerotisation of the male copulatory organ. Three new species are from Australia (B. bipartita n. sp., B. quadricirrata n. sp., and B. tricirrata n. sp.), one from the western Mediterranean (B. galerita n. sp.), two from Brazil (B. pseudovalkanovi n. sp. and B. brusai n. sp.), and one from the USA (B. floridana n. sp.). The phylogenetic analysis is based on published and newly obtained 18S and 28S rDNA sequences from six species of the related taxon Cheliplana and two of Baltoplana, confirming the monophyly of Cheliplanidae. Baltoplana, as currently circumscribed, was strongly rejected as monophyletic. The monophyletic status of the genus Cheliplana remains uncertain: the species included here form a clade, but with support below the thresholds applied in this study. We also present a partial mitogenome of B. valkanovi comprising four protein-coding genes and three tRNAs, and provide an identification key.