Taxonomy and phylogeny of Dalytyphloplanida Willems et al., 2006 (Platyhelminthes: Rhabdocoela), with the description of a new family, a new genus, and sixteen new species from Cuba and Panama

Abstract Twenty-two marine species of Dalytyphloplanida from Cuba, Panama, and Lanzarote are presented, sixteen of which are new to science. Five known species are recorded from Cuba: Kytorhynchus microstylus , Ceratopera paragracilis , Trigonostomum armatum , T . franki , and T . vanmecheleni . Neokytorhynchus pacificus is recorded for the first time in the Atlantic (Lanzarote). For one species, a new genus is erected to be included in a new family. A new genus and thirteen new species from Cuba and three new species from Panama are described. The new species are mainly distinguished from their congeners by the specific morphology of the copulatory structures. The new taxa are discussed in the context of a new phylogenetic analysis of Dalytyphloplanida. This analysis includes sequences of 238 species, 14 of which were sequenced for the first time. The phylogenetic analysis and the detailed morphology suggest that K . microstylus may constitute a complex of cryptic species. The internal phylogenetic relationships of Trigonostomum and Promesostoma were separately analysed to include new sequence data of the mitochondrial cox1 gene. These genera are shown to consist of several diagnosable clades, concurring with the results of early morphological studies of these taxa. Morphological and molecular data support the notion that Trigonostomum sinensis is a junior synonym of T . vanmecheleni , and we therefore propose their synonymisation. A new family is erected, Schockaertiidae fam. n. , to include a monophyletic clade of neodalyellids with a pharynx rosulatus and a copulatory bulb devoid of hard structures ( Schockaertia aprostatica gen. n. sp. n. and Einarella argillophyla ). We propose a new classification into families of Thalassotyphloplanida, which envolves elevating the status of Adenorhynchinae to family level (Adenorhynchidae status novus ). All previously recognised thalassotyphloplanid families are recovered as monophyletic (Kytorhynchidae, Byrsophlebidae, Promesostomidae, and Trigonostomidae). No support was found for the previously described subfamilies, except Paramesostominae, and we, therefore, propose to suppress these taxa.