Man-Ki Jeong

A new species of the genus Hexapleomera Dudich, 1931 from the South Korea, with molecular evidence (Crustacea, Tanaidacea, Tanaididae)

Abstract Two populations of new species are described for Hexapleomera Dudich, 1931 from the southeastern coast and Jeju island of South Korea (north west Pacific). The specimens were collected using a light trap set overnight at the entrance near a pier or harbour. Hexapleomera ulsana sp. n. is clearly differentiated from other species in the genus by the uropod with five articles, a maxillule palp with four distal setae, the maxilliped coxa with three proximal setae, the epignath with short and blunt spiniform seta, the propodus of pereopods 2–3 with three ventral setae, and the maxilla with a rugged shape of the distal margin. Differences of mitochondrial cytochrome c oxidase subunit I (mtCOI) gene observed between two populations of H. ulsana from different regions (Ulsan and Jeju Island) and between H. ulsana and H. urashima (Japan) were 1.1 % and 32.4 %, respectively. Two genetically-close populations differed in the setae on pleopod 3, the proximal setae on the maxilliped coxa, and the ventral setae on pereopods 2–3, which showed that geographical distance affected the morphological divergence. In addition, a comprehensive comparison with previous records of Hexapleomera was conducted and close examinations on the appendages, known to have morphological variations between the individuals of one species and/or between different genders, were carried out based on new species and discussed herein.

A new species of Leiochrides from the Korean subtidal waters with notes on the taxonomic status of the genus Pseudomastus (Annelida, Capitellidae)

Abstract Leiochrides yokjidoensis sp. n., collected from the sublittoral muddy bottom in southern Korea, is described as a new species. The taxonomic status of the monospecific genus Pseudomastus has been a subject of controversy for many years, as its characteristics overlap those given in recent generic definitions of Leiochrides. The results of a comprehensive review and comparison regarding the two genera, based on previous records showed minor differences. In this study, a detailed description of L. yokjidoensis sp. n. is given and a comparison with closely related species is tabulated and discussed.The taxonomic status of Pseudomastus is discussed and the genus placed in synonymy with Leiochrides.

A new Notomastus (Annelida, Capitellidae) species from Korean waters, with genetic comparison based on three gene markers

Abstract Notomastus koreanus sp. n., collected from the sublittoral muddy bottom of Korean waters, is described as a new species. The Korean new species closely resembles N. torquatus Hutchings & Rainer, 1979 in the chaetal arrangement and the details of abdominal segments, but differs in the position of genital pores and the absence of eyes. DNA sequences (mtCOI, 16S rRNA, and histone H3) of the new species were compared with all the available sequences of Notomastus species in the GenBank database. Three genes showed significant genetic differences between the new species and its congeners (COI: 51.2%, 16S: 38.1–47.3%, H3: 3.7–9.3%). This study also includes a comprehensive comparison of the new Korean Notomastus species with its most closely similar species, based on the morphological and genetic results.

Two new species of the genus Zeuxo (Peracarida: Tanaidacea) from the west and south coast of Korea

Two new species of Zeuxo Templeton 1840 are described from the western and southern coast of Korea (North West Pacific). Zeuxo gracilis n. sp. and Z. spina n. sp. belong to the “Z. normani species complex”. Zeuxo gracilis is distinguished from species within this complex by the following morphological combination in females: the spine row of the left mandible bears a bifid spiniform seta; pleonites 4 and 5 bear one and two lateral setae, respectively; the cheliped merus bears two ventral and two inner setae; and pereopods 2–6 bear a distal simple seta on merus. Zeuxo spina shows unique features characterized by a serrated ventral seta on each propodus of pereopods 2 and 3 and the cheliped merus bearing two ventral and one inner setae. Additional character states are proposed for defining new and/or sibling species within the Z. normani species complex. In order to confirm the presence/absence of morphological variations of Zeuxo, detailed morphological features between same- and different-sized females of Z. gracilis are compared and discussed.