Genetics do not reflect habitat differences in Riseriellus occultus (Heteronemertea, Nemertea) from Spain and Wales

Abstract

The description of the heteronemertean species Riseriellus occultus was based on specimens from Spain, where they live imbedded in sand, and Wales, where the specimens were collected intertidally under stones and rocks. Considering these habitat differences, which are not known from any other nemertean conspecifics, we asked if this instead is an example of two sibling species that could not be separated by morphology. We sequenced specimens for the two mitochondrial genes cytochrome oxidase I (COI) and 16S and estimated an intraspecific phylogenetic network using statistical parsimony. This analysis did not disclose any differences congruent with geography/habitat; neither did the phylogenetic analysis using maximum likelihood. The phylogenetic analysis also included new sequences of Lineus longissimus, a species with many external characters in common with Riseriellus occultus.

Keywords:

• Intraspecific variation
• mitochondrial DNA
• molecular systematics

Published in collaboration with the University of Bergen and the Institute of Marine Research, Norway, and the Marine Biological Laboratory, University of Copenhagen, Denmark

Published in collaboration with the University of Bergen and the Institute of Marine Research, Norway, and the Marine Biological Laboratory, University of Copenhagen, Denmark

Acknowledgments

We are grateful to Eric McEvoy for assistance with the sampling in Wales, and to Juan Junoy for sampling support in Spain. Ray Gibson kindly helped with the identification of the Welsh specimens. This research is supported (to PS) by the Swedish Research Council, and by the Nilsson-Ehle and Axson Johnson funds (to MS).

Notes

Published in collaboration with the University of Bergen and the Institute of Marine Research, Norway, and the Marine Biological Laboratory, University of Copenhagen, Denmark