Original articleBless this phylogeographic mess - Comparative study of Eiseniella tetraedra (Annelida, Oligochaeta) between an Atlantic area and a continental Mediterranean area in Spain

•Eiseniella tetraedra presents a great variability in the Iberian Peninsula.•There were no clear differences between Atlantic and Mediterranean areas.•Worldwide localities were more homogeneous.•No correlation was found between morphological and genetic data.

Due to the influence of Atlantic Ocean and Mediterranean Sea, Spain has different climates, from desert to Atlantic. We sampled the parthenogenetic earthworm Eiseniella tetraedra in two different biogeographical zones in Spain, in order to study their genetic diversity and test their potential distinctiveness. Moreover, we evaluated the presence or absence of two different lineages (Eurosiberian and Mediterranean) found in other parthenogenetic earthworms such as Aporrectodea trapezoides and A. rosea. We studied the molecular markers COI, 16S and 28S. E. tetraedra presents a high diversity in Spain (one COI haplotype every two individuals were found) and no clear geographical patterns except for diffuse patterns along the Guadarrama River basin. In contrast, worldwide localities were more homogeneous with low diversity, to be confirmed with further samples. After morphological study, no correlation was found between phylogenetic relationships and the diagnostic characters for the previously described subspecies in E. tetraedra.