Changes in Fecal Pellet Microbiome of the Cold-Adapted Antarctic Copepod Tigriopus kingsejongensis at Different Temperatures and Developmental Stages.

Tigriopus kingsejongensis, a copepod species reported from the King Sejong Station, Antarctica, serves as a valuable food resource in ecosystems. We cultured T. kingsejongensis at three different temperatures (2 °C, 8 °C, and 15 °C) in a laboratory to observe the changes in its fecal pellet microbiome depending on the cultivation temperatures and developmental stages. We observed that the fecal pellet microbiome of the copepod changed with temperature: a lower microbial diversity, higher abundance of the aquatic bacterium Vibrio, and lower abundance of the psychrophilic bacterium Colwellia were noted at higher temperatures. In addition, the fecal pellet microbiome of the copepod changed according to the developmental stage: a lower microbial diversity was noted in egg-attached copepods than in nauplii at 8 °C. We further analyzed three shotgun metagenomes from the fecal pellet samples of T. kingsejongensis at different temperatures and obtained 44 metagenome-assembled genomes (MAGs). We noted that MAGs of V. splendidus D contained glycosyl hydrolases (GHs) encoding chitinases and virulence factors at a higher relative abundance at 15 °C than at lower temperatures. These results indicate that increasing temperature affects the fecal pellet microbiome and the development of copepods. The findings are helpful to understand the changes in cold-adapted copepods and the effect of temperature on their growth.

A New Polychaete, Scolelepis (Parascolelepis) Brunnea sp. nov. (Annelida: Spionidae), from Korea.

A new spionid polychaete, Scolelepis (Parascolelepis) brunnea sp. nov., from an intertidal mud flat in Korean waters, is reported. The new species is unique among species of Scolelepis Blainville, 1828 in having conspicuously long, reddish-brown branchiae on the anteriormost chaetigers. The new species is morphologically and genetically most closely related to Scolelepis (Parascolelepis) anterobranchiata Lee and Min, 2022 from Korea. However, the new species differs from the latter by a combination of the following characteristics: presence of reddish-brown pigmentations on anteriormost body, neuropodial hooded hooks appearing from chaetigers 21 to 22, larger size of worms, and three teeth above the main fang of neuropodial hooded hooks. Detailed description and images of the new species, along with three gene regions (cytochrome c oxidase subunit I [COI], 16S ribosomal DNA [16S rDNA], and 18S rDNA), are provided.

A study on the non-monophyletic genera Australothrix and Holostichides based on multigene and morphological analyses with a reexamination of type materials (Protozoa: Ciliophora).

In a study of ciliate diversity, we collected two new species of the genera Australothrix and Holostichides. Based on nuclear ribosomal genes, our study shows that these two genera are genetically non-monophyletic. To clarify the issues of the non-monophyly, we reexamined type material of H. heterotypicus, H. terrae, and Birojimia soyaensis. Based on multigene and morphometric analyses, Australothrix and Holostichides are clearly non-monophyletic even in mitochondrial CO1 gene trees. The multigene analyses show a clade composed of A. lineae sp. nov., H. terrae, and B. soyaensis, suggesting that a cytopharynx with argyrophilic structures might be their synapomorphy. A list of species with this type of cytopharynx is provided for further studies to either accept or reject this hypothesis. Based on the reexamination, we discriminate the morphologically nearly identical (cryptic/sibling) species H. obliquocirratus sp. nov. from H. heterotypicus and they show significant genetic dissimilarities in the multigene trees. They showed only few morphological (non-quantitative) differences and thus distinguishing them morphologically needs careful investigation.

Morphology and Molecular Phylogeny of Two New Terrestrial Ciliates, Australocirrus rubrus n. sp. and Notohymena gangwonensis n. sp. (Ciliophora: Oxytrichidae), from South Korea.

Two new soil oxytrichids, Australocirrus rubrus n. sp. and Notohymena gangwonensis n. sp., were discovered from South Korea. Morphologically, A. rubrus shares many features with A. australis, and these two species form a single clade in a molecular tree based on nuclear small subunit ribosomal RNA (SSU rRNA) gene sequences. Australocirrus rubrus mainly differs from A. australis in the color (citrine color vs. reddish) and distribution of the cortical granules. Additionally, we confirm that the genus Australocirrus is not a monophyletic group, as A. shii is separated from the clade comprising the other Australocirrus species, being clustered instead with other taxa. Notohymena gangwonensis n. sp. mainly differs from its congeners by the following combination of features: irregularly distributed cortical granules (vs. arranged in groups associated with cirri and dorsal kineties), variable four or five (usually four) transverse cirri (vs. invariable five), and the anteriormost pretransverse cirrus V/2 on 13.2-16.1% of cell length (vs. on or above 18.9% of cell length). Currently, there are no available gene sequences for members of the genus Notohymena, thus we provide SSU rRNA gene sequences from the new species of Notohymena, as well as detailed morphological descriptions of the novel species.

Morphology and Molecular Phylogeny of Two New Ciliates, Holostichides heterotypicus n. sp. and Holosticha muuiensis n. sp. (Ciliophora: Urostylida).

Two new urostylid species, Holostichides heterotypicus n. sp. and Holosticha muuiensis n. sp., were discovered in South Korea. Morphological and phylogenetic analyses were carried out to confirm that these species are new to science. Holostichides heterotypicus is mainly characterized by the following combination of features: 110-205 µm long in vivo; 5-10 frontoterminal cirri; 6-8 midventral pairs with 2-3 midventral cirral rows; cortical granules present; four bipolar dorsal kineties; and 6-9 caudal cirri. Ontogenetic features of H. heterotypicus are similar to those of H. typicus. Phylogenetic analyses revealed that H. heterotypicus was distantly separated from bakuellid genera Apobakuella, Bakuella, Metaurostylopsis, and Neobakuella. This result is supported by the following features: transverse cirri (present in the other four bakuellids vs. absent in Holostichides) and caudal cirri (absent in the other four bakuellids vs. present in Holostichides). Holosticha muuiensis n. sp. is mainly distinguished from its congeners by the following combination of features: 100-185 long in vivo; shortened undulating membrane; cortical granules lacking; contractile vacuole absent; 51-66 adoral zone of membranelles; 42-60 macronuclear nodules; and five bipolar dorsal kineties. In the phylogenetic tree, Holosticha muuiensis n. sp. clustered with a Holosticha group (containing Holosticha diademata, Holosticha foissneri, and Holosticha heterofoissneri).

Pseudonotohymena antarctica n. g., n. sp. (Ciliophora, Hypotricha), a New Species from Antarctic Soil.

A new soil ciliate, Pseudonotohymena antarctica n. g., n. sp., from King George Island, Antarctica, is described based on live observation, protargol impregnation, and its 18S rRNA gene. The new genus Pseudonotohymena is morphologically similar to the genus Notohymena Blatterer and Foissner in the following characteristics: 18 fronto-ventral-transverse cirri, a flexible body, undulating membranes, dorsomarginal kineties, and the number of cirri in the marginal rows. However, Pseudonotohymena differs from Notohymena particularly in the dorsal ciliature, that is, in possessing a nonfragmented dorsal kinety (vs. fragmented). In addition, the molecular phylogenetic relationship of the new species differs from that of Notohymena species. On the basis of the morphological features, the genetic data, and morphogenesis, we establish P. antarctica n. g., n. sp. In addition, the cyst morphology of this species is described.

Morphology and Molecular Phylogeny of Pseudocyrtohymena koreana n. g., n. sp. and Antarctic Neokeronopsis asiatica Foissner et al., 2010 (Ciliophora, Sporadotrichida), with a Brief Discussion of the Cyrtohymena Undulating Membranes Pattern.

We discovered a new brackish water oxytrichid Pseudocyrtohymena koreana n. g., n. sp. in South Korea and investigated the new species on the basis of morphology, ontogenesis, and 18S rRNA gene sequences. The new genus has the 18 frontal-ventral-transverse cirri of typical oxytrichids with flexible body, cortical granules, Cyrtohymena undulating membranes (UM), and one left and one right marginal cirral row. Ontogenesis of the new species indicated that dorsal kinety anlage 3 stretches within the parental row without any fragmentations (Urosomoida pattern) and exclusively forms all caudal cirri. The new genus is morphologically similar to Cyrtohymena Foissner, 1989, but has the following distinctive features: (i) caudal cirri absent in dorsal kineties 1 and 2 (vs. present in Cyrtohymena); and (ii) dorsal kinety 3 nonfragmented (vs. fragmented in Cyrtohymena). Further, we collected an additional species Neokeronopsis asiatica Foissner et al. 2010, from King George Island, Antarctica, and the species shares the morphology of UM with Cyrtohymena. Herein, we describe the previously unidentified characteristics of N. asiatica (i.e., cortical granules, body flexibility, contractile vacuole, and 18S rRNA gene sequence). In addition, we obtained two 18S rRNA gene sequences from Cyrtohymena muscorum and Parasterkiella thompsoni to expand samples for phylogenetic analysis. Our 18S rRNA gene tree supports the hypothesis that the Cyrtohymena UM pattern might have evolved several times in hypotrichs (e.g., Neokeronopsidae, Oxytrichinae, and Stylonychinae).

Morphology and Molecular Phylogeny of Two New Brackish Water Ciliates of Bakuella (Ciliophora: Urostylida: Bakuellidae) from South Korea.

Two new species of Bakuella, B. (B.) incheonensis n. sp. and B. (Pseudobakuella) litoralis n. sp., were discovered in brackish water near Aamdo Shore Park, Incheon, South Korea. We conducted a morphological study based on live observations and protargol-impregnated specimens, and a molecular analysis using nuclear SSU rRNA gene sequences. Bakuella (B.) incheonensis is diagnosed by: body size 70-105 × 20-40 µm in vivo, 21-25 adoral membranelles, three or four frontoterminal cirri, midventral complex composed of 7-10 midventral pairs with one or two rows and terminating at about 62% of body length, 20-28 left and 25-32 right marginal cirri, 58-87 macronuclear nodules, and yellowish cortical granules. Bakuella (Pseudobakuella) litoralis is diagnosed by: body size 90-125 × 30-40 µm in vivo, 25-33 adoral membranelles, 3-5 buccal cirri, midventral complex composed 10-15 midventral pairs with one or two rows and terminated at 70% of body length, one or two pretransverse cirri, 3-6 transverse cirri, 26-39 left and 29-47 right marginal cirri, 49-84 macronuclear nodules, and two types of cortical granules. Molecular phylogeny using SSU rRNA gene sequences shows a nonmonophyletic relationship among Bakuella species and emphasizes the need for further morphogenetic studies of this genus and other related hypotrichs.

A new species and ten new records of bdelloid rotifers from Korea.

We conducted a taxonomic study of bdelloid rotifers collected from various terrestrial habitats, such as mosses, lichens, mushrooms on tree trunks, and leaf litter, at six different locations in Korea. The study yielded 10 new Korean records and a new species, Bradyscela hoonsooi n. sp. Among the 10 new Korean records, nine species are new to Asia, and seven of these are rare species with poorly known distributions. Our study is the first to record Habrotrocha fuscochlaena De Koning outside its type locality. Macrotrachela sonorensis Örstan and Habrotrocha acornis Murray have previously been reported from only two countries. Habrotrocha longula Bryce and Habrotrocha visa Donner are recorded outside Europe for the first time. Habrotrocha flaviformis De Koning has previously been reported from Europe, Brazil and New Zealand. Finally, Philodina grandis Milne has been reported from Eastern and Southern Africa and New Zealand before the present study. Here, we provide a description of the new species and discuss the taxonomy and distribution of the seven rare species.

Susceptibility of five species members of the Korean Hyrcanus Group to Brugia malayi, and hybridization between B. malayi-susceptible and -refractory Anopheles sinensis strains.

Five species members of the Korean Hyrcanus Group: Anopheles pullus, Anopheles sinensis, Anopheles kleini, Anopheles belenrae, and Anopheles lesteri were tested for susceptibility to Brugia malayi. They were allowed to feed artificially on blood containing B. malayi microfilariae and dissected 14 days after feeding. The susceptibility rates were 60%, 65%, 90%, 100% and 100% in An. pullus, An. sinensis, An. kleini, An. belenrae, and An. lesteri, respectively. As determined by levels of susceptibility, results indicated that An. pullus was a moderate potential vector, while An. sinensis, An. kleini, An. belenrae, and An. lesteri were high potential vectors, when compared with the 90-95% susceptibility rates of an efficient control vector, Ochlerotatus (=Aedes) togoi. An introgressive study of B. malayi-susceptible/-refractory genes was performed intensively by hybridization experiments between a high (Korean strain) and a low (Thailand strain) potential An. sinensis vectors. The susceptibility rates of F1-hybrids and backcross progenies were compared with parental stocks. The results indicated that the B. malayi-susceptible genes could be introgressed from a high to low potential An. sinensis vector by increasing the susceptibility rates from 0-5% in the parental stocks to 55% and 70% in F1-hybrids and backcross progenies, respectively. The increase of susceptibility rates related clearly to the increase of normal larval development in the thoracic muscles of F1-hybrids and backcross progenies.

Comparative analysis of complete mitochondrial genome sequences confirms independent origins of plant-parasitic nematodes.

BACKGROUND: The nematode infraorder Tylenchomorpha (Class Chromadorea) includes plant parasites that are of agricultural and economic importance, as well as insect-associates and fungal feeding species. Among tylenchomorph plant parasites, members of the superfamily Tylenchoidea, such as root-knot nematodes, have great impact on agriculture. Of the five superfamilies within Tylenchomorpha, one (Aphelenchoidea) includes mainly fungal-feeding species, but also some damaging plant pathogens, including certain Bursaphelenchus spp. The evolutionary relationships of tylenchoid and aphelenchoid nematodes have been disputed based on classical morphological features and molecular data. For example, similarities in the structure of the stomatostylet suggested a common evolutionary origin. In contrast, phylogenetic hypotheses based on nuclear SSU ribosomal DNA sequences have revealed paraphyly of Aphelenchoidea, with, for example, fungal-feeding Aphelenchus spp. within Tylenchomorpha, but Bursaphelenchus and Aphelenchoides spp. more closely related to infraorder Panagrolaimomorpha. We investigated phylogenetic relationships of plant-parasitic tylenchoid and aphelenchoid species in the context of other chromadorean nematodes based on comparative analysis of complete mitochondrial genome data, including two newly sequenced genomes from Bursaphelenchus xylophilus (Aphelenchoidea) and Pratylenchus vulnus (Tylenchoidea). RESULTS: The complete mitochondrial genomes of B. xylophilus and P. vulnus are 14,778 bp and 21,656 bp, respectively, and identical to all other chromadorean nematode mtDNAs in that they contain 36 genes (lacking atp8) encoded in the same direction. Their mitochondrial protein-coding genes are biased toward use of amino acids encoded by T-rich codons, resulting in high A+T richness. Phylogenetic analyses of both nucleotide and amino acid sequence datasets using maximum likelihood and Bayesian methods did not support B. xylophilus as most closely related to Tylenchomorpha (Tylenchoidea). Instead, B. xylophilus, was nested within a strongly supported clade consisting of species from infraorders Rhabditomorpha, Panagrolaimomorpha, Diplogasteromorpha, and Ascaridomorpha. The clade containing sampled Tylenchoidea (P. vulnus, H. glycines, and R. similis) was sister to all analyzed chromadoreans. Comparison of gene arrangement data was also consistent with the phylogenetic relationships as inferred from sequence data. Alternative tree topologies depicting a monophyletic grouping of B. xylophilus (Aphelenchoidea) plus Tylenchoidea, Tylenchoidea plus Diplogasteromorpha (Pristionchus pacificus), or B. xylophilus plus Diplogasteromorpha were significantly worse interpretations of the mtDNA data. CONCLUSIONS: Phylogenetic trees inferred from nucleotide and amino acid sequences of mtDNA coding genes are in agreement that B. xylophilus (the single representative of Aphelenchoidea) is not closely related to Tylenchoidea, indicating that these two groups of plant parasites do not share an exclusive most recent common ancestor, and that certain morphological similarities between these stylet-bearing nematodes must result from convergent evolution. In addition, the exceptionally large mtDNA genome size of P. vulnus, which is the largest among chromadorean nematode mtDNAs sequenced to date, results from lengthy repeated segments in non-coding regions.

Morphology, morphogenesis, and molecular phylogeny of Anteholosticha multicirrata n. sp. (Ciliophora, Spirotrichea) with a note on morphogenesis of A. pulchra (Kahl, 1932) Berger, 2003.

Two marine urostylid ciliates, Anteholosticha multicirrata n. sp. and Anteholosticha pulchra (Kahl, 1932) Berger, 2003, were collected from South Korea. These species were identified based on morphology, morphogenesis, and SSU rRNA gene sequence comparison. Anteholosticha multicirrata n. sp. is characterized by the following features: body size 90-125 × 30-45 µm in vivo, shape slender to ellipsoidal in outline, with yellow-greenish cortical granules distributed along and between dorsal kineties and cirri; single contractile vacuole positioned on left at mid-body; three frontal, five to seven frontoterminal, one buccal, one to two pretransverse and four to six transverse cirri; three complete dorsal kineties; one left and one right marginal cirral row; about 117 macronuclear nodules; and three to four micronuclei observed during morphogenesis. In addition, based on the observations of morphogenesis, we found that A. pulchra has pretransverse cirri, which were not described in detail in previous studies. Nuclear small subunit ribosomal RNA (SSU rRNA) gene was used to analyse their phylogenetic relationship, and the gene tree supports that the genus Anteholosticha is a highly polyphyletic group.

Genetic compatibility between Anopheles lesteri from Korea and Anopheles paraliae from Thailand.

To assess differentiation and relationships between Anopheles lesteri and Anopheles paraliae we established three and five iso-female lines of An. lesteri from Korea and An. paraliae from Thailand, respectively. These isolines were used to investigate the genetic relationships between the two taxa by crossing experiments and by comparing DNA sequences of ribosomal DNA second internal transcribed spacer (ITS2) and mitochondrial DNA cytochrome c oxidase subunit I (COI) and subunit II (COII). Results of reciprocal and F1-hybrid crosses between An. lesteri and An. paraliae indicated that they were compatible genetically producing viable progenies and complete synaptic salivary gland polytene chromosomes without inversion loops in all chromosome arms. The pairwise genetic distances of ITS2, COI and COII between these morphological species were 0.040, 0.007-0.017 and 0.008-0.011, respectively. The specific species status of An. paraliae in Thailand and/or other parts of the continent are discussed.

A new species of the genus Cephalodella (Rotifera, Monogononta) from Korea, with reports of four additional cephalodellid species.

A new monogonont rotifer, Cephalodellabinoculatasp. nov., was described from a soil sample collected in Korea. The new species is morphologically similar to C.carina but is distinguished by having two frontal eyespots, a vitellarium with eight nuclei, and the shape of its fulcrum. We also described four other cephalodellid species collected in Korea; Cephalodellaauriculata, C.catellina, C.gracilis, and C.tinca. Of these four species, C.gracilis and C.tinca were newly recorded in Korea. We provided the morphological characteristics of the five Cephalodella species along with photographs of trophi observed with a scanning electron microscope. Furthermore, we provided the mitochondrial cytochrome c oxidase subunit I gene sequences of the five species.

The complete mitochondrial genome of a marine polychaete, Prionospio cf. japonica (Annelida: Spionidae).

Prionospio Malmgren 1867 is one of the abundant genera of the family Spionidae Grube, 1850. Despite its rich diversity, information on their complete mitochondrial genome has remained unknown. In this study, we determined the complete mitochondrial genome of a spionid polychaete, Prionospio cf. japonica Okuda 1935. The specimen was collected from the fine sand in the intertidal zone of South Korea. The mitogenome consists of 15,267 base pairs, harboring 13 protein-coding genes (PCGs), 22 transfer RNAs, and two ribosomal RNAs. The maximum-likelihood phylogenetic tree based on the 11 PCGs showed that Prionospio cf. japonica grouped with other spionid polychaetes and formed a monophyletic group. Also, the mtDNA of P. cf. japonica was more closely related to that of non-polydorin spionid, Marenzelleria neglecta, than polydorin spionids. The molecular data will be valuable for studying evolutionary relationships among annelids.

Strongylidium koreanum n. sp. (Protozoa: Ciliophora), a new soil species from South Korea.

Strongylidium koreanum n. sp., a new soil ciliate from Jeju Island, South Korea, is described based on live observations, protargol impregnation, and molecular analysis of the 18S rRNA gene sequence. It is characterized by the following morphological features: cell outline more or less fusiform, posterior end broader than anterior end; grayish under low magnification; cortical granules absent; 23-32 adoral membranelles; three enlarged frontal cirri; buccal cirrus and postoral ventral cirrus present; 27-42 left and 15-28 right ventral cirri; 23-36 left and 30-46 right marginal cirri; three dorsal kineties; three caudal cirri; and two macronuclear nodules with two or three micronuclei. Phylogenetic analyses show that Strongylidium is monophyletic.

Two new species of feather mites (Acariformes, Astigmata) from the black-tailed godwit, Limosalimosa (Charadriiformes, Scolopacidae), in Korea.

Two new species of feather mites are described from two individuals of the black-tailed godwit, Limosalimosa (Linnaeus, 1758), in Korea: Alloptes (Conuralloptes) neolimosaesp. nov. (Analgoidea, Alloptidae) and Phyllochaetalimosae sp. nov. (Pterolichoidea, Syringobiidae). Males of A. (C.) neolimosaesp. nov. are distinguished from A. (C.) limosae in having the hysteronotal shield with a straight anterior margin, setae h2 enlarged and slightly flattened in the basal half, and the terminal lamella monotonously transparent without sclerotized patches; females differ in having legs IV with ambulacral discs extending to or slightly beyond the level of setae f2. The discovery of P.limosae sp. nov. represents the first record of the feather mite genus Phyllochaeta on godwits of the genus Limosa Brisson, 1760 (Scolopacidae, Limosinae). Males of P.limosae sp. nov. are distinguished from P.secunda in having the terminal cleft semi-ovoid with a length-to-width ratio of 1.7, and the terminal membranes with 15 or 16 finger-shaped denticles; females differ in having the hysteronotal shield bearing faint longitudinal striations in the posterior third and lacking lacunae, and setae c1 situated posterior to the level of setae c2. Additionally, we obtained partial sequences of the mitochondrial cytochrome c oxidase subunit I (COI) gene from A. (C.) neolimosaesp. nov. and estimated genetic distances from 10 other Alloptes species based on comparisons of COI sequences.

Two new Scolelepis species (Annelida: Spionidae) from the Yellow Sea in Korea.

Two new spionid polychaetes of the genus Scolelepis from the intertidal habitats of the Yellow Sea in Korea are described and illustrated. Scolelepis (Parascolelepis) anterobranchiata sp. nov. is characterized by a combination of the following characteristic: palps with smooth globular expansions at the basal part, branchiae appearing in the anterior part of the body, absence of notochaetae in chaetiger 1, notopodial postchaetal lamellae partially fused with branchiae in anterior chaetigers, and neuropodial hooded hooks appearing from chaetigers 1819 with two pairs of teeth surmounting a well-developed main fang. Scolelepis (Scolelepis) rubra sp. nov. can be distinguished from its congeners by the following characteristics: reddish-pink body, presence of notochaetae in chaetiger 1, branchiae approximately twice as long as notopodial postchaetal lamellae, neuropodial bidentate hooded hooks usually appearing from chaetigers 2631, and presence of notopodial hooded hooks in posterior chaetigers. Based on molecular data, the sequences of the two new species showed relatively large genetic distances from other Scolelepis species in COI (15.819.5%) and 16S rDNA (4.915.8%). Morphological variability of prostomial shape in the genus Scolelepis is discussed for the first time.

Morphology and molecular phylogeny of Keronopsis koreana n. sp. (Ciliophora, Hypotricha), a new soil species from South Korea.

The morphology and molecular phylogeny of a new soil ciliate, Keronopsis koreana n. sp., which was discovered in soil from Jindo-gun, South Korea, were investigated. The new species is characterized by the following morphological features: cell more or less ellipsoid or ovoid, both ends broadly rounded; cortical granules irregularly distributed, colorless, 1 µm across; 35-54 adoral membranelles; 12-23 cirri in frontal corona; two frontal and two frontoventral cirral rows; two or three buccal cirri; 23-38 left and 22-37 right marginal cirri; three bipolar dorsal kineties; and two macronuclear nodules and three to five micronuclei. Phylogenetic analyses show that Keronopsis koreana n. sp. is placed within a clade containing K. helluo (type species of Keronopsis) and species belonging to Paraholosticha, Uroleptoides, Parabistichella, Orthoamphisiella, Lamtostyla, and Bistichella in non-dorsomarginalian hypotrichs. Also, the sequences belonging to the Keronopsidae did not cluster together. In addition, a new combination is provided: Parabistichella tasmaniensis (Blatterer and Foissner, 1988) n. comb. (original combination: Keronopsis tasmaniensis).

Eobathynella gwangjuensis sp. nov., a new species of Parabathynellidae (Crustacea, Bathynellacea) from South Korea.

A new species of Parabathynellidae (Crustacea, Bathynellacea) was found in the interstitial groundwater of the Yeongsangang River in South Korea. The new species belongs to the genus Eobathynella Birstein and Ljovuschkin, 1964, which previously comprised six species, including two from South Korea. Eobathynella gwangjuensis sp. nov. can be distinguished from its congeners by the absence of setae on the last segment of the thoracopod endopods and by the presence of three finger-like setae on the exopod of male thoracopod VIII. In addition, we present gene sequences of the nuclear 18S rDNA and the mitochondrial cytochrome c oxidase subunit 1 of the new species, which was used to infer phylogenetic relationships with closely related species.