A new spider species of the genus Pholcus Walckenaer, 1805, Pholcus osaek sp. nov., in the family Pholcidae C.L. Koch, 1850, is described from Korea. This new species belongs to phungiformes-group in the genus. It can be distinguished from its congeners by the shape and structure of genital organs of both males and females. It is found on and between rock walls in mountainous mixed forests. Additionally, the taxonomic status of Pholcus uksuensis Kim & Ye, 2014 is revalidated, re-diagnosed, and redescribed based on specimens collected from the type locality. Considering differences mentioned in the diagnosis through revalidation, P. uksuensis is regarded as a distinct species. Therefore, it should be removed from the synonymy of P. woongil Huber, 2011.

Two spider species of the genus Pholcus Walckenaer, 1805, Pholcus muju sp. nov. and Pholcus yeongheung sp. nov. in the family Pholcidae C. L. Koch, 1850 are newly described from Korea. These two new species belonging to phungiformes-group in the genus can be distinguished from their congeners by the shape and structure of genital organs of both males and females. They are found on rock walls in mountainous mixed forests. This work provides diagnoses, detailed descriptions, and taxonomic photographs for these new species.

This study describes two new species, Desmoscolex (Desmoscolex) delticeps sp. nov. and Desmoscolex (Desmoscolex) obtusiseta sp. nov. Belonging to the subgenus Desmoscolex, they were discovered in subtidal habitats along the coast of Korea. Detailed morphological analyses of the two new species were conducted using differential interference contrast (DIC) microscopy and scanning electron microscopy (SEM). D. (D.) delticeps sp. nov. was collected from subtidal zones near Ulleungdo Island. It is characterized by a broadly triangular head with robust cephalic setae and centrally positioned oval amphidial fovea. Its somatic setae are arranged in 17 main rings. Its conical terminal ring ends in a long, uncovered spinneret. D. (D.) obtusiseta sp. nov. was collected from distant subtidal zones along the western coast. It is characterized by short, blunt cephalic setae situated on peduncles, a flattened anterior head, and an oval amphidial fovea with a central pore. Its somatic setae are arranged in 17 main rings. Its terminal ring tapers ventrally, ending in a short spinneret. This study highlights distinctive cephalic setae morphologies of these species, providing a deeper understanding of nematode diversity in Korean subtidal zones and contributing to the advancement of marine nematode taxonomy.

방아벌레과에 속하는 제주도청동방아벌레(신칭)을 신종으로 보고한다. 본 종은 제주도 고유종으로, 국내 근연종들과 구별이 쉽도록 종 검색 표와 진단형질을 제공한다.

두줄가슴무당벌레붙이속의 붉은두줄가슴무당벌레붙이와 좁은두줄가슴무당벌레붙이 두 종이 한국에서 처음으로 보고된다. 또한, 외부형태 및 생식기의 삽화, 진단특징, 분포도, 그리고 분류키를 제공한다.

가는납작벌레과의 미기록종인 Ahasverus advena (Waltl) (곡식가는납작벌레, 신칭), Psammoecus trimaculatus Motschulsky (닮은모래가 는납작벌레, 신칭)을 한국에서 처음으로 보고한다. 각 종에 대한 외형과 진단형질, 분포지도를 제공한다.

The genus Muscidideicus Becker, 1917 is comprised of only one species, M. praetextatus (Haliday, 1855) reported in west Palearctic region. The adults were typically found on sandy beach within the intertidal zone. In the survey of Korean fauna, authors found three new to science species of this genus on the west sea side of Korean Peninsula and Jeju Island. Descriptions and figures of external features of new to science species and key to species of the world are provided here.

The mayfly genus Drunella is the most diverse genera in the family Ephemerellidae, and is found in lotic streams throughout East Asia and North America. The species D. ishiyamana is found widely throughout East Asia and their species concept has not been properly defined until recently. The D. ishiyamana species group was examined, and morphological and molecular evidence of a new species were uncovered. In this study Drunella punctata sp. nov. is formally described, mainly distinguished from D. ishiyamana by the lack of a notch in their median clypeal tubercle in their larval stage. Photographs, diagnosis, and descriptions of D. punctata are provided.

The genus Campylomyza Meigen, 1818, from the Micromyinae subfamily of the Cecidomyiidae, includes 40 known species globally. The genus Campylomyza has been primarily studied within the Palearctic region, with 39 species, 2 from the Nearctic region, and 1 from the Oriental region. As of now, four species have been documented in Korea: Campylomyza appendiculata, C. flavipes, C. furva, and C. spinata. Our research from 2017 to 2020 uncovered five previously unreported species in Korea (C. abjecta, C. aborigena, C. cornuta, C. cavitata, and C. cingulata) and introduces seven new species (C. angusta sp. nov., C. ambulata sp. nov., C. convexa sp. nov., C. cornigera sp. nov., C. hori sp. nov., C. odae sp. nov., and C. yeongyangensis sp. nov.). These findings are based on morphological evidence and DNA analysis. We present comprehensive data, including the mitochondrial COI sequences, diagnoses, detailed descriptions, and identification keys for these species. This work was supported by a grant from the National Institute of Biological Resources (NIBR), funded by the Ministry of Environment (MOE) of the Republic of Korea.

The genus Trixagus Kugelann is one of the most diverse genera in the family Throscidae Laporte, which comprises about 80 species. Only a single species of this genus has been reported in Korea throughout the entire family. In this study, three additional species, Trixagus sp., Trixagus leseigneuri Muona, and Trixagus turgidus Hisamatsu are reported for the first time in Korea. Similar to that of the species illustrated in Kovalev, males of Trixagus leseigneuri Muona and Trixagus turgidus Hisamatsu possess sexual modification on mesotarsus. Trixagus sp. and Trixagus turgidus Hisamatsu exhibit characters that are unusual for this genus, including the unincised eye, a blade-like structure on the protibia, and others. Illustrations of habitus and diagnostic characters of each species are provided.