Earthworm<i>Drawida</i>(Moniligastridae) Molecular phylogeny and diversity in Far East Russia and Northeast China

Abstract

In the Sikhote-Alin and Changbai Mountains of the Amur River region, earthworms of genus Drawida inhabit the northern boundary of their natural habitat. They are represented by the epigeic and anecic life-forms, three steady colour morphs and eight valid species, yet the genetic lineages of 11 have yet to be described. Based on mt-COI gene fragment sequence data, epigeic and anecic earthworms are shown to differ from one another at the interspecific level. Polymorphism and genetic intraspecific diversity are an obligatory sign for a species in the refuge even at the boundary of its distribution where this species occupies new ecological niches. The original habitats of the ancient Drawida black morph were within the Paleo-Amur River basin in the Late Neogene. Today, the meadow-swampy drawidas protrude far north along the Amur River floodplain up to the border of the last freezing in this region in comparison to the forest earthworms. However, at similar northern latitudes such as the Kuril Islands and the Sakhalin, Drawida are absent, because the soil on these islands during the last Ice Age was permafrost. The black epigeic drawidas only live in the floodplain meadows. The grey and brown morphs of the anecic species live in same forest biotopes, where they inhabit different soil horizons.