Kichoon Kim

New insights into polyphyly of the harpacticoid genus Delavalia (Crustacea, Copepoda) through morphological and molecular study of an unprecedented diversity of sympatric species in a small South Korean bay

Polyphyly of the genus Delavalia Brady, 1869 has been postulated previously based on intuitive methods, but no phylogenetic study was ever conducted. A chance discovery of seven sympatric species of this genus in the highly industrialized Gwangyang Bay in South Korea, in addition to one species each from the closely related genera Stenhelia Boeck, 1865 and Onychostenhelia Itô, 1979, prompted a renewed interest in the phylogenetic relationships within the subfamily Stenheliinae Brady, 1880. Additional surveys along the Korean coast failed to produce Delavalia species, but comparative material was sourced from Posyet Bay in the Russian Far East. Aims of this study were to reconstruct phylogenetic relationships of the newly collected stenheliins using molecular methods, test the hypothesized polyphyly of Delavalia, formally describe any resulting monophyletic units, perform a comparative study of traditional morphological and novel micro-morphological characters, and describe all new Delavalia species. A fragment of the mtCOI gene was successfully PCR-amplified from 23 stenheliin specimens and an additional 300 specimens were studied for morphological characters. All phylogenetic analyses supported the presence of at least eight genetically divergent lineages, most with very high bootstrap values, and the polyphyletic nature of Delavalia is demonstrated. Three new genera, each supported by molecular data and a number of morphological synapomorphies, were erected to accommodate the newly discovered species and some previously described members of Delavalia: Wellstenhelia gen. nov., Itostenhelia gen. nov., and Willenstenhelia gen. nov. The Chinese Wellstenhelia qingdaoensis (Ma & Li, 2011) comb. nov. is recorded for the first time in Korea, and six new species are described from Gwangyang Bay: Wellstenhelia calliope sp. nov., Wellstenhelia clio sp. nov., Wellstenhelia erato sp. nov., Wellstenhelia euterpe sp. nov., Itostenhelia polyhymnia sp. nov., and Willenstenhelia thalia sp. nov. Additonally, Itostenhelia golikovi (Chisleno, 1978) comb. nov. is redescribed from newly collected material from the type locality in Russia and its male described for the first time, while Wellstenhelia melpomene sp. nov., Willenstenhelia urania sp. nov., and Willenstenhelia terpsichore sp. nov. are established as new names for previously reported populations of two presumably widely distributed Delavalia species.

Morphological and molecular affinities of two East Asian species of Stenhelia (Crustacea, Copepoda, Harpacticoida)

Abstract Definition of monophyletic supraspecific units in the harpacticoid subfamily Stenheliinae Brady, 1880 has been considered problematic and hindered by the lack of molecular or morphology based phylogenies, as well as by incomplete original descriptions of many species. Presence of a modified seta on the fifth leg endopod has been suggested recently as a synapomorphy of eight species comprising the redefined genus Stenhelia Boeck, 1865, although its presence was not known in S. pubescens Chislenko, 1978. We redescribe this species in detail here, based on our freshly collected topotypes from the Russian Far East. The other species redescribed in this paper was collected from the southern coast of South Korea and identified as the Chinese S. taiae Mu & Huys, 2002, which represents its second record ever and the first one in Korea. A fragment of the mtCOI gene was successfully PCR-amplified from two specimens of each species, which represents the first molecular data for this genus, and from additional 19 specimens belonging to six different species of other stenheliins from Korea and Russia. Reconstructed phylogenies confirm previously postulated monophyly of Stenhelia and polyphyly of the closely related genus Delavalia Brady, 1869. Average pairwise maximum likelihood distances between S. pubescens and S. taiae are only slightly above 10%, suggesting a very close relationship despite numerous newly discovered micro-morphological differences and despite macro-morphological similarities being probable plesiomorphies.

A new species of Enhydrosoma (Copepoda: Harpacticoida: Cletodidae) from Korea, with redescription of E. intermedia and establishment of a new genus

Abstract Two species of Enhydrosoma Boeck, 1873, found in muddy sediments in the sublittoral zone of Gwangyang Bay, represent the first record of this genus in Korea. Enhydrosoma coreana, new species, shares a number of rare morphological features with the type species, E. curticauda Boeck, 1872, such as a bifid rostrum with centrally inserted sensilla, endopodal lobe of P5 with a peduncle, and a characteristic shape of the female genital field. They differ in the armature formula of the mandible, P1 endopod, and P5 exopod, size of the P5 peduncle, and minor details in the ornamentation of several somites. Enhydrosoma intermedia Chislenko, 1978 is redescribed from its holotype, freshly collected Korean material, and freshly collected material from and near its type locality in the Russian Far East. Its male is described for the first time. Minor morphological differences are observed between these two disjunct populations, such as longer caudal rami and sparse hair-like spinules on somites in Korean specimens. However, molecular data from the mtCOI gene suggest them to be conspecific. Detailed morphological comparisons between E. coreana and E. intermedia reveal a number of important differences, and molecular phylogenies suggest only a remote relationship. Their average pairwise maximum likelihood distances are very similar to those between other well-established genera of harpacticoid copepods. Geehyndrosoma, new genus, is erected to accommodate E. intermedia, together with E. brevipodum Gómez, 2004, from the Pacific coast of Mexico.

A new species of Schizopera (Copepoda: Harpacticoida) from Japan, its phylogeny based on the mtCOI gene and comments on the genus Schizoperopsis

The predominantly marine genus Schizopera Sars, 1905 has only two significant inland water species-flocks, one in the ancient African Lake Tanganyika and the other in subterranean waters of Western Australia. Discovery of Schizopera abei sp. nov. from several interstitial locations in the vicinity of the ancient Lake Biwa has wider implications for the study of morphological homoplasies in the genus, as well as for the study of freshwater invasions in harpacticoid copepods. The new Schizopera species belongs to a small group of congeners with a two-segmented endopod of the fourth leg, which used to be recognised as a separate genus, Schizoperopsis Apostolov, 1982. Our reconstructed phylogenies based on the mtCOI partial sequences suggest that this character probably evolved convergently in at least some Schizopera, thus rendering the genus Schizoperopsis polyphyletic. However, almost all basal nodes in our cladograms are weakly supported, which shows limitations of a single-gene approach for reconstructing phylogenetic relationships. The new species is the first member of its genus from Japanese inland waters, and it has no close relatives among extent congeners anywhere in the world. We speculate that its ancestor may have invaded Lake Biwa, and subsequently its surrounding subterranean waters, from brackish areas around central Japan, presumably during a period of high sea water level through its major outflow river. This discovery may provide further support for the hypothesis about the role of ancient lakes as biodiversity pumps for subterranean habitats. http://zoobank.org/urn:lsid:zoobank.org:pub:1F71F7AD-B7C8-4AD3-BE44-5E1BEE4E2AA8

Concordance between molecular and morphology-based phylogenies of Korean Enhydrosoma (Copepoda: Harpacticoida: Cletodidae) highlights important synapomorphies and homoplasies in this genus globally.

Three new species of Enhydrosoma Boeck, 1873 are described from Korea, all found in muddy sediments in the sublittoral zone. They also all have a bifurcate rostrum, just like the type species of this genus, E. curticauda Boeck, 1872, and one recently described Korean representative, E. coreana Kim, Trebukova, Lee & Karanovic, 2014. These five species share a number of other morphological features, and mostly differ in details of integumental relief, caudal rami shape, and ornamentation of the male antennula. We aim to compare molecular and morphology-based phylogenies obtained for four Korean species of Enhydrosoma and two other members of the family Cletodidae: Geehydrosoma intermedia (Chislenko, 1978) from Korea and Russia and Stylicletodes sp. from Korea. Similar studies in other animal groups have helped to reevaluate the suitability of morphological characters for reconstructing phylogenetic relationships and taxonomic revisions, and the genus Enhydrosoma is considered to be polyphyletic and in urgent need of revision. We use partial sequences of the mtCOI gene for our molecular phylogeny and 32 non-additive characters for our morphology-based phylogeny. High congruence between all cladograms suggests that reconstructing phylogenetic relationships in this group of harpacticoids may be straight-forward, but highlights as homoplastic some morphological characters previously considered important for defining supraspecific taxa in this family. On the other hand, some characters previously overlooked in species descriptions show a significant phylogenetic signal. Even though there is no doubt about the monophyly of the Korean Enhydrosoma, their high average pairwise maximum likelihood distances suggest only a remote relationship, and explain their sympatry and/or parapatry. Weak bootstrap support for our basal nodes in molecular phylogenies shows limitations of a single-gene approach, and probably cannot be resolved without a wider taxon and character sampling. Wider taxon sampling will also be necessary to improve bootstrap values of basal nodes in morphology-based cladograms.

A new species of the genus Normanella (Copepoda: Harpacticoida) from Gwangyang Bay, Korea

Abstract A new species of Normanellidae is described from Gwangyang Bay, Korea. This species is placed in the genus Normanella Brady, 1880 based on the following morphological characteristics: 1) 5-segmented female antennule, 2) antennary exopod with four setae, 3) mandible with discrete endopod and two setae on basis, 4) maxillule with two basal endites, 5) maxilla with allobasis accompanied by two setae and a spine, and 6) the sixth leg of the male with three setae. Normanella spinosa, new species, is closely related to Normanella bifida Lee & Huys, 1999. However, the new species is clearly distinguished by the characteristic processes on the dorsal surface, especially well-developed, large spiny-form processes on the urosome. In addition, N. spinosa has a sharply pointed rostrum, and the P1 enp-1 with a smaller inner seta than that of N. bifida. Normanella spinosa also displays substantial abnormalities of the reduced setal number in the swimming legs. This is the first report of the family Normanellidae from Korea.

Study of morphological deformity of Tigriopus japonicus s. l. by mid-ultraviolet radiation (UVB)

Abstract The damaging effect of mid-ultraviolet (UVB, 280–315 nm) radiation on a marine copepod, Tigriopus japonicus sensu lato was investigated. Copepods were collected from tidal pools on rocky shores, Yeosu, on the south coast of Korea, and were cultured under constant conditions (temperature: 20°C, salinity: 20 psu, L : D = 12 : 12 h) in the laboratory. Each stage of nauplius (N1–N6) and copepodite (CI–CVI) was harvested from the culture and exposed to one of eight irradiation doses (1, 5, 10, 15, 20, 25, 30, and 35 kJ m−2) of UVB. No deleterious effect was induced by UVA or PAR. Extensive morphological deformities were observed, i.e., shrunken body (in groups 5 kJ m−2 at N4; 1 and 15 kJ m−2 at CI), in the urosome and caudal rami (5 and 15 kJ m−2 at N6; 10 kJ m−2 at CI), in the swimming legs (5, 10, and 15 kJ m−2 at CI; 10 kJ m−2 CIV), and in the antennule (5 kJ m−2 at CIII; 1 kJ m−2 at CIV). The types of deformity observed depended on the developmental stages of copepods that were exposed to UVB radiation. UVB radiation had a damaging effect on the morphology of T. japonicus s. l. Exposure of earlier larval stages to mid-ultraviolet affected the shape of the entire body, and the prosome shape was abnormal. Exposure of later larval stages to mid-ultraviolet resulted in abnormalities at the appendage level, i.e., in the antennules and swimming legs.

A new species of Harpacticella Sars, 1908 (Copepoda, Harpacticoida), from a tidal pool on Jeju Island, Korea.

Abstract A new species of the genus Harpacticella Sars, 1908 is described from a tidal pool on Jeju Island, Korea. Harpacticella jejuensis sp. n. is closely related to Harpacticella itoi Chang & Kim, 1991, with regard to the structure of P1 exp-1 and enp-1, the length of P1 exp-1 and exp-2, and the setal number of the P5 exopod in males. However, the new species is clearly distinguishable from Harpacticella itoi by the combined following characters: six setae on the P5 exopod in females, one naked seta on the inner margin of P1 exp-2, the short endopod of P1 compared to the exopod, and a naked long seta on the proximal inner margin of the P5 exopod of males. The mtCOI partial sequence is provided as a DNA barcode for the new species.

A new species of Sentiropsis (Copepoda: Harpacticoida: Pseudotachidiidae) from the upper sublittoral zone off Hyeopjae beach, Jeju Island, Korea, and a key to genera of the subfamily Danielsseniinae

Abstract Both sexes of a new species of Sentiropsis Huys & Gee, 1996 (Copepoda, Harpacticoida, Pseudotachidiidae) are described from the upper sublittoral zone off Hyeopjae, Jeju Island, Korea. Sentiropsis coreana, new species is very similar to its zoogeographically closest congener, S. vietnamensis Gómez & Chertoprud, 2009 from Nha Trang Bay (Vietnam) in the South China Sea. Females of both species differ primarily in morphometric characters. The presence of a well-developed apophysis on the male P2 endopod of S. coreana serves to distinguish it from the Caribbean type species, S. minuta (Coull, 1973) and calls into question the previously suggested sister-group relationship between Sentiropsis and the Paradanielssenia-lineage characterized by the presence of claviform aesthetascs on the mouthparts. An updated key to the 19 valid genera of the subfamily Danielsseniinae is provided. The genus Carolinicola Huys & Thistle, 1989 is removed from the Pseudotachidiidae and transferred to the subfamily Hemimesochrinae in the Canthocamptidae.