Molecular phylogeny of European Runcinida (Gastropoda, Heterobranchia): The discover of an unexpected pool of complex species, with special reference to the case of Runcina coronata

Abstract

Runcinida is a small heterobranch order of sea slugs with 61 known species distributed worldwide across temperate and tropical latitudes with two established families (Ilbiidae and Runcinidae). Little is known about the phylogenetic relationships within Runcinida. Here, we present the first molecular phylogeny of the order with an emphasis on European species and we discuss the taxonomic status of the type species Runcina coronata. Molecular phylogenetics based on the mitochondrial genes cytochrome c oxidase subunit I and 16S rRNA and nuclear gene histone H3 is used to investigate relationships between species. Detailed morpho-anatomical worked was additionally employed to study Runcina coronata. Our results suggest the monophyly of Runcinida and showed that Runcina coronata is a complex of four species, namely: R. coronata proper, R. aurata and two new species here formally described (R. caletensis sp. nov. and R. tingensis sp. nov.)This study was supported by several research projects,‘Anfiatlantismo, alopatría y espécies crípticas en moluscos opistobranquios, con especial atención a los de la región Ibero-Balear-Macaronésica’ funded by Ministry of Education and Science (CGL2006-05182/BOS) to J. L. Cervera, ‘Diversidad de moluscos opistobranquios en Bermuda y biogeografía del Océano Atlántico’ funded by Ministry of Science and Innovation (CTM2008-05228-E/MAR) to J.L. Cervera, ‘Progess in Mediterranean Sea Slugs biodiversity’ ASSEMBLE (7th FP) grant agreement no.22779 to J. L. Cervera, ‘La Caleta (Cádiz) e intermareales rocosos asociados: una ventana permanente al conocimiento de la biodiversidad marina’ funded by Fundación Biodiversidad of the Ministry for the Ecological Transition and ‘Desentrañando la diversidad criptica en las regions Lusitánica y Mediterránea: Heterobranquios marinos (Mollusca), Sílidos (Annelida) y Caprélidos (Arthropoda, Pancrustacea) como casos de estudio’ funded by the University of Cadiz (PR2018-039) to J. L. Cervera. A. K. Araujo holds a PhD grant from the Conselho Nacional de Desenvolvimento Científico e Tecnológico– CNPq/Brazil (Processo 205276/2014–8