Abstract
The enchytraeid fauna of three areas in Jeju Island (Korea) was studied, and comparative morphological and molecular taxonomic examinations (based on CO1, ITS and H3 sequences) were performed on nine samples collected in 2016. Twenty-two enchytraeid species were recorded and identified. The descriptions of two new species (Achaetamultisacculatasp. n. and Fridericiafloriformissp. n.) are presented in this paper. The main diagnostic features of A.multisacculatasp. n. are: three pairs of pyriform glands per segment, clitellum with two “baguette-like” packages of glands, dorsal blood vessel from VII, secondary pharyngeal glands absent, oesophageal appendages well developed, two pairs of preclitellar nephridia, the reproductive organs (except the spermathecae in V) shifted one segment forward. The main features of F.floriformissp. n. are that they are large worms, have up to 2–4 chaetae in bundles, strong body wall, thick cuticle, five pairs of preclitellar nephridia, c-type coelomo-mucocytes sometimes with some refractile vesicles, chylus cells in XII–XV, sperm funnels approximately twice as long than wide, spermathecae with long ectal duct without glands, ampullae surrounded distally by about 9–12 sessile diverticula of varying size. Molecular phylogenetic analyses supported the morphological results and confirmed the status of the two new species.
Highlights
The investigation of the previously unknown enchytraeid fauna of Korea has been continuing since 2007
The morphological studies are supplemented with molecular taxonomic analyses targeting the mitochondrial cytochrome c oxidase subunit 1 (CO1) gene, the nuclear ribosomal ITS region and the nuclear histone 3 (H3) gene, as in earlier studies (Dózsa-Farkas et al 2015, 2018)
22 enchytraeid species belonging to seven genera were found in the samples (Table 1), among which two are new to science: Achaeta multisacculata sp. n. and Fridericia floriformis sp. n
Summary
The investigation of the previously unknown enchytraeid fauna of Korea has been continuing since 2007. Results have been published in four previous papers that yielded a total of 19 species new to science (Dózsa-Farkas and Hong 2010; Christensen and Dózsa-Farkas 2012; Dózsa-Farkas et al 2015; Dózsa-Farkas et al 2018). For Jeju Island, the fauna of Hallasan National Park (Mount Hallasan) was studied and published separately (Dózsa-Farkas et al 2018). Further faunistic results from the lowland areas of Jeju Island, outside the Hallasan National Park, are presented, including two new species. The morphological studies are supplemented with molecular taxonomic analyses targeting the mitochondrial cytochrome c oxidase subunit 1 (CO1) gene, the nuclear ribosomal ITS region and the nuclear histone 3 (H3) gene, as in earlier studies (Dózsa-Farkas et al 2015, 2018). Morphologically similar species and species described previously from Korea have been selected
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