Present and future of the study on Korean land planarians (Platyhelminthes: Tricladida: Geoplanidae)

To date, two species of land planarians, Diversibipalium koreense (Frieb, 1923) and Microplana unilineata (Frieb, 1923), have been recorded for the Republic of Korea. Meanwhile, various morphotypes of land planarians were discovered during the terrestrial invertebrate sampling campaign conducted in 2020, predicting that many species may inhabit the country. Accordingly, we initiated an international collaborative research in 2021 to elucidate the biodiversity of land planarians in the country and to document each species. We grouped more than 70 specimens collected from 2020 to 2022 into 22 morphospecies based on their external appearance. Subsequently, we tested the morphospecies independently in a molecular phylogeny inferred from the mitochondrial COI gene. Maximum likelihood (ML) analysis suggests that the 22 morphospecies are assigned to each clade as follows: (1) Bipaliinae (15 spp.), (2) Microplaninae (6 spp.), and (3) Rhynchodeminae (1 sp.). The Assemble Species by Automatic Partitioning (ASAP) analysis predicted that there would be 14 species of Bipaliinae instead of 15, reducing the number of putative species to 21. As previous sampling campaigns have only covered a small portion of the Republic of Korea, the expected number of species should be much higher. We hope that this international collaboration will continue to help reveal the true richness of Korean land planarians.

KEYWORDS:
ASAP; COI; molecular phylogeny; Republic of Korea; richness