Revisiting kinorhynch segmentation: variation of segmental patterns in the nervous system of three aberrant species.

BACKGROUND: Kinorhynch segmentation differs from the patterns found in Chordata, Arthropoda and Annelida which have coeloms and circulatory systems. Due to these differences and their obsolete status as 'Aschelminthes', the microscopic kinorhynchs are often not acknowledged as segmented bilaterians. Yet, morphological studies have shown a conserved segmental arrangement of ectodermal and mesodermal organ systems with spatial correspondence along the anterior-posterior axis. However, a few aberrant kinorhynch lineages present a worm-like body plan with thin cuticle and less distinct segmentation, and thus their study may aid to shed new light on the evolution of segmental patterns within Kinorhyncha. RESULTS: Here we found the nervous system in the aberrant Cateria styx and Franciscideres kalenesos to be clearly segmental, and similar to those of non-aberrant kinorhynchs; hereby not mirroring their otherwise aberrant and posteriorly shifted myoanatomy. In Zelinkaderes yong, however, the segmental arrangement of the nervous system is also shifted posteriorly and misaligned with respect to the cuticular segmentation. CONCLUSIONS: The morphological disparity together with the distant phylogenetic positions of F. kalenesos, C. styx and Z. yong support a convergent origin of aberrant appearances and segmental mismatches within Kinorhyncha.

Description of a New Species for Asian Populations of the "Cosmopolitan" Perinereis cultrifera (Annelida: Nereididae).

An Asian species of Perinereis, which has been regarded as a local population of a cosmopolitan species P. cultrifera ( Grube, 1840 ) (type locality: Italy), is described as a new species, P. euiini., based on Korean specimens. This new species is distinguishable from P. cultrifera and other similar species such as P. floridana ( Ehlers, 1868 ) (type locality: USA), P. anderssoni Kinberg, 1866 (type locality: Brazil), and P. helleri ( Grube, 1878 ) (type locality: Philippines) by the character combination of the absence of lateral group of paragnaths in area III on the proboscis, the presence of small notopodial prechaetal lobe in anterior parapodia, and the greatly expanded dorsal ligule in posterior parapodia. All previous records of "P. cultrifera" from eastern Asia (Taiwan, China, Japan, and Korea) are judged to belong to P. euiini sp. nov., leading to the conclusion that P. cultrifera is not a cosmopolitan species. Specimens previously identified as P. cultrifera var. floridana (or P. cultrifera floridana) in eastern Asia are also judged to belong to P. euiini sp. nov., although they have different paragnath number in area V (one instead of three). Their aberrant paragnath number was regarded as an intraspecific variation of P. euiini sp. nov. The comparison of DNA sequences of the mitochondrial cytochrome c oxidase subunit I (COI) between P. euiini sp. nov. and "P. cultrifera" from China and Portugal also supports the erection of the new species.

The complete mitochondrial genome of Hyperhalosydna striata (Kinberg, 1856) (Annelida: Polynoidae) collected from Jejudo Island, Korea.

The mitogenome sequence of Hyperhalosydna striata was determined for the first time in the present study. The genome is 15,226 bp long and contains 13 protein-coding genes (PCGs), two ribosomal RNA genes (rRNAs), and 22 transfer RNA genes (tRNA). The overall base composition was 28.0% A, 21.9% C, 13.0% G, and 37.1% T. A phylogenetic tree was constructed to infer the phylogenetic position of H. striata among polynoid species whose mitochondrial genome sequences are available in GenBank. Hyperhalosydna striata was closely related to the species of subfamily Lepidonotinae.

Circumtropical distribution and cryptic species of the meiofaunal enteropneust Meioglossus (Harrimaniidae, Hemichordata).

Hemichordata has always played a central role in evolutionary studies of Chordata due to their close phylogenetic affinity and shared morphological characteristics. Hemichordates had no meiofaunal representatives until the surprising discovery of a microscopic, paedomorphic enteropneust Meioglossus psammophilus (Harrimaniidae, Hemichordata) from the Caribbean in 2012. No additional species have been described since, questioning the broader distribution and significance of this genus. However, being less than a millimeter long and superficially resembling an early juvenile acorn worm, Meioglossus may easily be overlooked in both macrofauna and meiofauna surveys. We here present the discovery of 11 additional populations of Meioglossus from shallow subtropical and tropical coralline sands of the Caribbean Sea, Red Sea, Indian Ocean, and East China Sea. These geographically separated populations show identical morphology but differ genetically. Our phylogenetic reconstructions include four gene markers and support the monophyly of Meioglossus. Species delineation analyses revealed eight new cryptic species, which we herein describe using DNA taxonomy. This study reveals a broad circumtropical distribution, supporting the validity and ecological importance of this enigmatic meiobenthic genus. The high cryptic diversity and apparent morphological stasis of Meioglossus may exemplify a potentially common evolutionary 'dead-end' scenario, where groups with highly miniaturized and simplified body plan lose their ability to diversify morphologically.

Discovery of a New Sea Spider Belonging to the Genus Pycnogonum (Pycnogonida: Pycnogonidae) in the Mesophotic Zone of Jejudo Island, Korea.

A new species of the genus Pycnogonum was discovered in the mesophotic zone of Munseom Islet, Jejudo Island, Korea. Pycnogonum (Nulloviger) bifurcatum sp. nov. is the first case of sea spiders in Korean fauna not only included in the subgenus Nulloviger but also collected in the mesophotic zone of Munseom Islet. The new species is morphologically close to Pycnogonum (Pycnogonum) asiaticum and P. (N.) carinatum, sharing the granular integument, the dorsomedian tubercles on the trunk, and the post-ocular tubercle. The new species can be easily distinguished from the congeners by combination of the following characteristics: the prominent dorsomedian tubercles on the trunk, the lateral processes 1-3 touching each other, and the small auxiliary claws. A key is provided to distinguish 12 species of the subgenus Nulloviger morphologically, and molecular data of the new species are provided for species identification and further studies.

Micropipette tip intubation in rats as a replacement for conventional endotracheal tube intubation.

Endotracheal intubation is often necessary in the course of animal experiments, especially in craniofacial surgery. However, endotracheal intubation can be a major burden in this context. The authors performed simple and cost-saving method using a 200 µL yellow micropipette tip, and the success of this method was demonstrated by X-ray and autopsy. We used a total of 30 rats. After the rats were fixed with a plaster, the trachea and vocal cords were visualized with the tongue pulled back. Under direct visualization of the vocal cords, a curving micropipette tip was advanced into the trachea. This method can be learned quickly and applied successfully by general experimenters. We successfully intubated all 30 rats without any complications. The success rate of micropipette tip intubation was 100%. This procedure was performed by one experimenter within 2 to 3 minutes after induction of anesthesia. We demonstrated its superiority by X-ray and autopsy. Herein, we describe endotracheal intubation of rats using micropipette tips. To the best of our knowledge, this method is novel and represents the simplest and most efficient means of intubation in rats, providing an alternative to conventional endotracheal intubation.

Removal of an intraosseous hemangioma of the frontal bone through an anterior hairline incision: a case report.

An intraosseous hemangioma of the frontal bone is typically removed via a coronal incision. This procedure, while effective, can be lengthy and may result in complications such as a prominent scar and hair loss. An alternative approach involves a direct incision in the forehead, which leaves a less noticeable scar and allows a quicker recovery. However, in this specific case, the patient declined both coronal surgery and surgery through a direct forehead incision due to cosmetic concerns. Therefore, we proposed an anterior hairline incision. A 35-year-old woman presented with a firm, non-mobile, palpable mass on her right forehead. Preoperative non-contrast computed tomography revealed a heterogeneous osteolytic lesion. We performed an excisional biopsy through the anterior hairline. Postoperative non-contrast computed tomography was conducted 2 and 6 months after surgery. The wound was clean and free of complications, and there was no local recurrence. Partial resection can reduce scarring for patients who are concerned about cosmetic outcomes. However, the potential for recurrence remains a significant concern. We present this case of an anterior hairline incision for a hemangioma located in the forehead, evaluated using serial computed tomography for both preoperative and postoperative imaging.

The first high-quality genome assembly and annotation of Patiria pectinifera.

The blue bat star, a highly adaptive species in the East Sea of Korea, has displayed remarkable success in adapting to recent climate change. The genetic mechanisms behind this success were not well-understood, prompting our report on the first chromosome-level assembly of the Patiria genus. We assembled the genome using Nanopore and Illumina sequences, yielding a total length of 615 Mb and a scaffold N50 of 24,204,423 bp. Hi-C analysis allowed us to anchor the scaffold sequences onto 22 pseudochromosomes. K-mer based analysis revealed 5.16% heterozygosity rate of the genome, higher than any previously reported echinoderm species. Our transposable element analysis exposed a substantial number of genome-wide retrotransposons and DNA transposons. These results offer valuable resources for understanding the evolutionary mechanisms behind P. pectinifera's successful adaptation in fluctuating environments.

First record of the symbiotic palaemonid shrimp Pontonidessibogae Bruce, 2005 (Crustacea, Decapoda, Palaemonidae) from Korea.

Background: A single specimen of Pontonidessibogae was collected from a dendrophylliid coral by trimix SCUBA diving at a depth of 75 m during fieldwork around Jejudo Island, Korea in 2020. The morphology of the specimen corresponds closely to the main diagnostic characters of the holotype, especially in the presence of a distinct tubercle on the eyestalk, as well as the second pereiopod with fusiform setae along the dorsal border of the ischium. New information: The genus Pontonides had previously not been reported from Korean waters. Herein, colour photographs are provided, as well as an illustrated description including previously unreported characteristics.

Population genetic analysis reveals secondary contact between Eriocheir sinensis and E. japonica in South Korea.

BACKGROUND: The Chinese mitten crab (Eriocheir sinensis) and the Japanese mitten crab (E. japonica) of the family Varunidae, which are also critical fishery species in their native habitats, including China, Japan, and South Korea, exhibit a rare migration life history for the decapod life cycle. Eriocheir sinensis and E. japonica in South Korea may have originated from speciation or secondary contact in South Korea after speciation of these two species; however, the genetic relationship between these South Korean populations remains unclear, and need to be clarified. OBJECTIVE: This study examined the population genetic properties of E. sinensis and E. japonica in South Korea to reveal the origin of their co-existence. METHODS: Mitochondrial DNA cytochrome c oxidase I sequences of 120 E. sinensis and E. japonica from 6 sampling sites in South Korea were sequenced. Their genetic diversity and haplotype data were compared to previously reported data from the Chinese mainland, Taiwan, Japan, and Russia. RESULTS: The haplotype network, analysis of molecular variance, FST values, Mantel test, and Bayesian skyline plot results of South Korean E. sinensis and E. japonica demonstrated that E. sinensis and E. japonica were isolated from their central populations, Chinese and Japanese populations, by the distance due to the temperature, salinity, ocean current flow, or a geohistorical event. In addition, genetic analysis indicated that the South Korean populations of the two species were marginal populations, exhibiting low genetic diversity, significant negative neutrality values, and radial haplotype networks. The current results also suggest that the Geum River is an overlapping habitat for the natural populations of E. sinensis and E. japonica in South Korea. Further research is required to examine the geohistorical and evolutionary event between E. sinensis and E. japonica in South Korea. CONCLUSIONS: The co-existence of E. sinensis and E. japonica in South Korea may have originated from secondary contact after their speciation.

Characterization of the complete mitogenome of the estuarine benthic ribbon worm Yininemertes pratensis (Sun and Lu 1998) (Nemertea: Lineidae).

The complete mitogenome of the estuarine ribbon worm Yininemertes pratensis (Sun and Lu 1998) (Nemertea: Lineidae) was sequenced for the first time in the present study. The total length of the newly sequenced mitogenome is 15,616 bp, and it includes 13 protein-coding, 2 rRNA, and 24 tRNA genes, in addition to a noncoding region of 571 bp. The phylogenetic position of Y. pratensis was examined through maximum-likelihood analysis using a concatenated dataset of 13 protein-coding genes from seven selected nemertean species. Yininemertes pratensis is placed within the pilidiophoran group and is closely related to Lineus alborostratus among the selected nemerteans. The newly determined mitogenome sequence will further our knowledge for future phylogenetic and ecological studies of this species.

Complete mitochondrial genome of the commensal scale worm, Arctonoe vittata (Grube, 1855) (Polychaeta: Polynoidae), collected from benthic habitat of the eastern coast of Korea.

The complete mitogenome sequence of the commensal polynoid scale worm Arctonoe vittata was determined for the first time in the present study. The total length of the newly sequenced mitogenome was 15,125 bp, including 13 protein-coding genes, 2 rRNA genes, and 22 tRNA genes. The phylogenetic position of A. vittata was examined by maximum likelihood analysis using concatenated 13 protein-coding genes with 18 selected polychaete species. Arctonoe vittata was nested within the suborder Aphroditiformia and closely related to Aphrodita australis among the selected species. The newly determined mitogenome sequence will be useful for further phylogenetic and evolutionary studies of this group.

On the genus Mesopontonia Bruce, 1967 (Crustacea: Decapoda: Palaemonidae) in Korea, with the description of a new species.

Mesopontonia verrucimanus and Mesopontonia kimwoni sp. nov. are recorded from high-latitude temperate waters in Munseom Islet, Jejudo Island, Republic of Korea, with both species collected on gorgonians and sponges by trimix diving between 50 and 75 m depth. Mesopontonia kimwoni sp. nov. is morphologically allied to M. brevicarpus, but can be distinguished by the cutting edges of the fingers of the first chela being entire. Significant morphological variation in the rostrum as well as the second pereiopods is documented in M. verrucimanus, although cytochrome c oxidase subunit I (COI) barcode analysis proves this to be infra-specific variation. A key to species of the genus Mesopontonia is provided.

Morphological and molecular study on Yininemertespratensis (Nemertea, Pilidiophora, Heteronemertea) from the Han River Estuary, South Korea, and its phylogenetic position within the family Lineidae.

Outbreaks of ribbon worms observed in 2013, 2015, and 2017-2019 in the Han River Estuary, South Korea, have caused damage to local glass-eel fisheries. The Han River ribbon worms have been identified as Yininemertespratensis (Sun & Lu, 1998) based on not only morphological characteristics compared with the holotype and paratype specimens, but also DNA sequence comparison with topotypes freshly collected near the Yangtze River mouth, China. Using sequences of six gene markers (18S rRNA, 28S rRNA, histone H3, histone H4, 16S rRNA, and COI), the phylogenetic position of Y.pratensis was inferred among other heteronemerteans based on their sequences obtained from public databases. This analysis firmly placed Y.pratensis as a close relative to Apatronemertesalbimaculosa Wilfert & Gibson, 1974, which has been reported from aquarium tanks containing tropical freshwater plants in various parts of the world as well as a wild environment in Panama.

The complete mitochondrial genome sequence of Squalidus multimaculatus (Cypriniformes: Cyprinidae).

This study determined the complete mitogenome sequence of Squalidus multimaculatus (Cypriniformes: Cyprinidae). The mitogenome of S. multimaculatus is 16,597 bp in length, including 13 protein-coding genes, 22 transfer RNAs, 2 ribosomal RNA genes, and a non-coding control region. NCR is 925 bp in length, is located between tRNApro and tRNAphe. The overall base composition of S. multimaculatus is 27.9% for A, 18.9% for G, 25% for T, 28.2% for C, with a slight AT bias (52.9%). These results will provide the data required for phylogenetic studies of the Squalidus species.

Determination of complete mitogenome sequence for Eastern Asian population of Cheilonereis cyclurus (Harrington, 1897) (Polychaeta: Nereididae).

Complete mitogenome sequence for eastern Asian population of Cheilonereis cyclurus (Polychaeta: Nereididae) was determined for the first time. The length of circular genome of C. cyclurus is 14,917 bp including 13 protein-coding genes, two rRNA genes, 22 tRNA genes, and a non-coding region of 383 bp. The gene order of C. cyclurus is identical to that of the following four nereidid species: Hediste diadroma, Namalycastis abiuma, Paraleonnates uschakovi, Tylorrhynchus heterochaetus. The phylogenetic position of C. cyclurus compared to 16 selected polychaetes was conducted and present species is closely related to the clade containing Perinereis nuntia, P. aibuhitensis, and Platynereis dumerilii with high bootstrap value.

Complete mitochondrial genome sequence of the giant mud worm Paraleonnates uschakovi Khlebovich & Wu, 1962 (Polychaeta: Nereididae).

Complete mitochondrial genome sequence of the giant mud worm Paraleonnates uschakovi (Polychaeta: Nereididae) was determined in this study for the first time. The mitogenome of P. uschakovi is 15,540 bp in length. It has 13 protein-coding genes, two rRNA genes, 22 tRNA genes and a non-coding region. Mitogenome analysis of P. uschakovi showed inversion in the positions of three tRNAs compared to the mitogenome sequences of Perinereis aibuhitensis, P. nuntia and Platynereis dumerilii. The phylogenetic position of P. uschakovi compared to 15 selected polychaetes was investigated. P. uschakovi was grouped into the family of Nereididae. It is closely related to the clade containing Tylorrhynchus heterochaetus and Namalycastis abiuma.

Molecular detection of Bartonella spp. in terrestrial leeches (Haemadipsa rjukjuana) feeding on human and animal blood in Gageo-do, Republic of Korea.

BACKGROUND: Leeches can transmit pathogens and are therefore potentially hazardous to human and animal health. However, only a few studies of diseases transmitted by land leeches have been reported. The purpose of the present study was to analyse which pathogens are carried in Haemadipsa rjukjuana, the first recorded sanguivorous land leech in the Republic of Korea (ROK). FINDINGS: A total of 173 H. rjukjuana were collected from Mt. Dock-Sil on Gageo-do Island, ROK during July 2011. Conventional PCR was conducted for analysis of the origin of blood meal, as well as for detection of species of Anaplasma, Bartonella, Borrelia, Ehrlichia, Rickettsia, and Wolbachia in the leech specimens. Bartonella DNA was detected in eight of the specimens studied based on partial ITS sequence analysis. Seven of the DNA samples were closely related to Bartonella grahamii (99.6-100 % similarity), and one sample exhibited a 90.6 % similarity with Bartonella sp. from Taiwan. Sequences of the mitochondrial cytochrome b gene were generated for a total of 35 of the 173 leech internal organ samples. These included sequences of human (n = 10), mouse (n = 8), weasel (n = 6) and bird (n = 11) origin. Of these 35 sequences, 68.5 % were from mammals, including humans, and 31.4 % were from migratory birds that pass through Gageo-do, ROK. CONCLUSIONS: Although the present study does not provide evidence that leeches indeed transmit Bartonella species to hosts directly, to our knowledge this is the first report on Bartonella DNA being detected from leeches. Therefore, further studies are needed to explore the possibility of zoonotic pathogen transmission by land leeches.