Mitochondrial COII sequences indicate that the parthenogenetic earthworm Octolasion tyrtaeum (Savigny 1826) constitutes of two lineages differing in body size and genotype

Adult individuals of the parthenogenetic earthworm Octolasion tyrtaeum (Savigny 1826) differ considerably in body size. The length of adult specimens reaches 10-14 cm in some habitats, in others just 5-8 cm. In some habitats, individuals of both size classes coexist. Until now, size differences in O. tyrtaeum were ascribed to environmental rather than genetic factors. We used DNA-sequences of the mitochondrial gene for cytochrome oxidase II (COII) to measure genetic distances between O. tyrtaeum specimens of different size classes. Individuals of different geographical sites (including five sites in Germany and one site in Canada) were analysed. There was a strong correlation between the size of the earthworms and the COII sequences; large specimens separated clearly from small specimens. While sequences of large specimens were almost identical, those of small specimens were more diverse. This indicates that O. tyrtaeum consists of two morphologically and genetically different lineages. (C) 2003 Elsevier GmbH. All rights reserved.