Jin Hee Wi

Two species of the genusoncaea (copepoda, poecilostomatoida, oncaeidae) from the east sea, Korea

Oncaea venusta Philippi, 1843 has been known as having some different size groups, but recent genetic study for cyt b and ITS 1 (Elverset al. 2006) suggests that these size groups can be considered as different species. Of these size groups, the largestO. venusta Philippi and the smallestO. venella Farran, 1929 were first described in Korean waters. The latter is easily distinguishable from the former in the following characteristics in addition to its small size: (1) length to width ratio of genital double somite of two genders smaller, and (2) female second pediger bearing inconspicuous dorso-posterior swelling.Oncaea venusta andO. venella co-occur in Korean waters during spring to fall, but their occurrence patterns seasonally differ: the former shows higher density in fall while the latter does in summer.

Evidence for ontogenetic feeding strategies in four calanoid copepods in the East Sea (Japan Sea) in summer, revealed by stable isotope analysis

Deciphering the ontogenetic feeding ecology of copepods is essential to understanding their role in the energy transfer of marine ecosystems. We used stable isotope analysis to examine the ontogenetic feeding strategies of the four coexisting calanoid copepods, Mesocalanus tenuicornis, Metridia pacifica, Calanus sinicus, and Neocalanus plumchrus, in the East Sea (Japan Sea) in summer. Moreover, we used the stable carbon and nitrogen isotope composition of small-sized plankton in three cell size fractions, pico- (< 2 μm), nano- (2–20 μm) and microplankton (20–200 μm), to identify the dietary preference at each developmental stage. The relative carbon masses of pico-, nano- and microplankton were 18, 38, and 44%, respectively, and their δ13C and δ15N values gradually increased with increasing size classes. The ontogenetic trophic position of four copepods were relatively low and ranged from 2.1 to 2.6, indicating that herbivores feed on small-sized phytoplankton, pico- and nanoplankton. Among copepodid stages, the δ13C and δ15N values of M. tenuicornis and C. sinicus differed significantly, while those of M. pacifica and N. plumchrus were not significantly different. In M. tenuicornis, the smallest species among the four copepods examined, the diet preference of CIV for picoplankton changed to nanoplankton in the adult stage. When M. pacifica developed from CIV to adult, the diet preference changed from pico- to microplankton. The proportion of microplankton in the diet of C. sinicus and N. plumchrus increased from CIV to female adult and from CIII to CV, respectively. During the developmental progress in copepodid stages, the smaller copepods significantly changed their dietary preference from pico- to microplankton, while the larger copepods consistently fed on microplankton. We suggest that smaller copepods have an advantage in survival at early copepodid stages compared with larger copepods in summer when microplankton biomass is relatively low.

Two new species of the deep-sea genus Neotanais Beddard, 1886 (Tanaidacea: Neotanaididae) from the eastern central Pacific

We describe two new species of deep-water neotanaids collected from the Korea Deep Ocean Study (KODOS) Area in the eastern central Pacific. Neotanais pacificus is distinguished from other species of Neotanais by the following morphological combination: in the female: 1) pereiomere 5 is the longest of the pereiomeres, 2) distal claw of the cheliped fixed finger bulges outward, and the cutting edge descends steeply, 3) the uropod exopod is much longer than first endopodal article, 4) the setal row of the left mandible has bi-serrated setae and plumose seta, 5) the maxilliped endite bears three bipinnate spiniform setae on the inner posterior margin and medially expanded plumose seta on the distal margin, and 6) the propodi of pereipods 1 to 3 bear thick bi-pinnate spiniform setae. The female of N. capillus distinctly differs from other species of Neotanais by the following morphological combination: 1) pereiomeres 4 and 5 are longer than wide, 2) the pleomeres are without midventral spurs, 3) the pleotelson bears fine setules along the distal margin, 4) the maxilliped endite has a very long plumose seta on the distal outer corner and two bipinnate spiniform setae on inner posterior margin, 5) the propodi of pereiopods 1 to 6 have thick bipinnate spiniform setae, and 6) the uropod is shorter than the pleon. In this study, distinct morphological characters differentiating the N. pacificus and N. capillus from other species of Neotanais are given on the basis of detailed descriptions.

A new genus and species of Sphyrapodidae (Crustacea, Peracarida, Tanaidacea) from the southern coast of the South Korea

Abstract Wandogarida canalicula gen. n et sp. n. (Tanaidacea, Sphyrapodidae) is described from the southern coast of Korea (NW Pacific). The genus is included in the subfamily Sphyrapodinae Guţu, 1980 by having a mandible lacking a palp. It has a close affinity with the genus Poligarida Bamber & Marshall, 2013 in the third pereonite having lateral pointed apophyses, the antennule of males with fringes of aesthetascs on articles 1 and 2 of the outer flagellum and the antenna with an elongate article 2. However, it is distinguished from Poligarida by having a maxillular palp. Wandogarida gen. n. can be differentiated from other genera within the subfamily Sphyrapodinae by the unique shape characterised by the male’s antennule article 1 with its rough denticles and a deep groove, pleonites each with a ventral hyposphenium, the maxillule with uniarticulate palp and the presence of prominent sexual dimorphism in the mouthparts. An identification key to the five genera of the subfamily Sphyrapodinae is presented.

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.

Three new species of the deep-sea genus ColletteaLang, 1973 (Tanaidacea; Colletteidae) in the eastern central Pacific

Three new species of ColletteaLang, 1973 are described from the Korea Deep Ocean Study (KODOS) area of the eastern central Pacific based on collections made at a depth of approximately 5000 m by R/V Onnuri. This study is a component of environmental impact research for manganese nodule mining in the Clarion-Clipperton Fracture Zone (CCFZ). Only one species of the genus Colletteahas previously been described from the CCFZ. This situation may result from similar morphologies among related species, a lack of samples, and the frequent poor quality of specimens which results from sampling difficulties. This paper describes three new Colletteaspecies from the KODOS area. These species vary in the characteristics of the cheliped propodus: in C. asperaand C. prominentia, this structure shows bark-like ornamentation on its outer surface. Additionally, the cephalothorax bears fine setules along the mid-lateral margins ( C. eminulaand C. aspera), and the cheliped fixed finger shows protrusions along the proximal incisive margin ( C. eminula). These characteristics have not yet been found in other species of the genus. In this study, full descriptions of new species of Colletteaand the key characters of genus are provided, and the comparison of these characteristics with those of closely related species is given.

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 deep-sea genus Parameiropsis (Copepoda: Harpacticoida) from the eastern central Pacific

Two new species of Parameiropsis are herein described that were identified from the Korean Deep Ocean Study (KODOS) in the Clarion-Clipperton Fracture Zone, located in the eastern central Pacific. Parameiropsis kodosensis n. sp. is similar to P. magnus Itô, 1983 in two key respects: the presence of a distal seta on the syncoxa of the maxilliped, and the general features of its swimming legs. However, P. kodosensis can be differentiated from P. magnus by a higher length-to-width ratio of the caudal ramus (2.5:1 and 1:1 respectively), the setal number on the exp-3 of P1, and the exp and benp of P5 are separated in P. kodosensis, while they are fused in P. magnus. Parameiropsis tetraspinosa n. sp. resembles P. peruanus Becker, 1974 in the absence of a fused seta in the outermost spine on the endopod of antenna and the general features of the swimming legs. However, P. tetraspinosa can be distinguished from P. peruanus by a higher length-to-width ratio of the caudal ramus (3.9:1 and 2.3:1 respectively), the presence of a distal seta on the syncoxa of the maxilliped, and by its medially fused P5. In this study full descriptions and a comparison with previously described species are provided. Additionally, a key to females of Parameiropsis species is given.

Three species of Ditrichocorycaeus (Copepoda, Cyclopoida, Corycaeidae) from Korean waters, with new identification parameters

Three species of Ditrichocorycaeus [D. dahli (Tanaka, 1957), D. lubbocki (Giesbrecht, 1981), and D. subtilis (Dahl, 1912)] are first redescribed from southern area of Jeju Island, Korea. Morphological details such as mouthparts, ornamentation of genital double-somite, spine lengths of legs, and proportional lengths of caudal setae, are provided as new identification keys separating each species within Ditrichocorycaeus and/or each genus within Corycaeidae. In particular, the number and location of each segment on the body and antenna are re-examined and precisely defined. Also, few valid morphological characters of this genus distinguishing it from other genera are newly proposed as follows: 1) prosomes of both sexes are five-segmented; 2) basis of maxilliped with relatively longer proximal seta than in other genera.