Extending the geographic distribution of Bryodrilus ehlersi (Annelida, Enchytraeidae): morphological and molecular comparison of Korean and European specimens

Abstract

Cryptic species are such evolutionary lineages that differ genetically but cannot or can only be hardly differentiated with traditional morphological methods, so they are classified as the same species. Several cryptic species have been discovered within the family Enchytraeidae and some of them have also been described formally. During the study of the enchytraeid fauna of South Korea, specimens were found which were identified as Bryodrilus ehlersi based on their morphological characters. This was an unexpected result, since this species is common in Northern and Central Europe but has not yet been found in the Far East. Sequence analysis of the mitochondrial cytochrome c oxidase subunit I gene, the nuclear histone 3 gene and the nuclear ribosomal ITS region showed unambiguously that the specimens collected in South Korea represent a different species. In this paper the description of this new cryptic species, Bryodrilus deogyunensis sp. n., is given with its comparison with the morphologically almost identical B. ehlersi.