The genus Hyadina Haliday, 1830 is reported for the first time from Korean fauna along with two nominate species: Hyadina fukuharai Miyagi, 1977, and H. pulchella Miyagi, 1977. Their diagnoses, external feature, and a key of these species are provided here.

Hitherto, 37 species in 10 genera under 4 subfamilies have been known from the Korean Peninsula. In this study, three newly recorded species are reported for the first time from Korea: Conops ceriaeformis ussuriensis Zimina, 1974, Physocephala pielina Chen, 1939, and Myopa picta Panzer, 1797. Morphological diagnoses and illustrations of these species are presented. Additionally, a key to all species of Conopidae from Korea is also provided.

An unrecorded gall midge was discovered from inflorescence galls on Castanopsis sieboldii (Makino) Hatus. ex T.Yamaz. & Mashiba, which is one of major components in evergreen forests on the Korean Peninsula. The galls occurred on 20 trees out of 230 on Yokiji Island. The gall midge was identified as Schizomyia castanopsisae Elsayed & Tokuda, 2018 (Diptera: Cecidomyiidae), using morphological characters and mitochondrial DNA cytochrome oxidase subunit 1 (COI) region sequences of gall midge’s larvae. The Barcode sequences of 40 samples collected from Yokji Island were identical, and the individuals from Yokji Island formed a clade with the individuals from Kyushu, with robust bootstrap support in a maximum likelihood tree. This result suggests the gall midges may have migrated from Kyushu, Japan to Yokji Island, South Korea. However, it is too early to determine if the gall midge is truly invasive or not at present due to paucity of distribution data in the country.

The family Baetidae is known to be the most species-rich family in the order Ephemeroptera. The genus Baetis contains up to 160 species, but members of the genus in East Asia are still poorly investigated. In this paper, Baetis spinoculis sp. nov., is described based on larval specimens collected in a stream of the Chiaksan mountain in Korea. While four species in the genus have been described in Korea: Baetis fuscatus (Linnaeus), B. silvaticus Kluge, B. pseudothermicus Kluge, and B. ursinus Kazlauskas, this new species is distinguished from other Korean baetid species by both genetic and morphological characteristics. B. spinoculis can be separated from the related B. pseudothermicus group by the COI genetic distant. The cuticle structures on paraproct plates and abdominal pigment patterns also distinguish B. spinoculis from B. pseudothermicus and other related species.

Moth flies (Diptera: Psychodidae) are small fuzzy flies found in diverse habitats from mountains to urban areas, even in your house. Approximately 3,000 species among 6 subfamilies are recorded worldwide. However, in Korea, only 10 species from 3 genera of the subfamily Psychodinae have been recorded, including 8 species from North Korea. A preliminary study on moth flies in Korea was conducted using specimens collected via malaise traps and by hands from various locations in South Korea. As a result, Brunettia lungjingensis, Thornburghiella decoricornis, Philosepedon monstruosus and our friendly but unrecorded, Clogmia albipunctata are newly described in Korea. Brief descriptions, photographs, and illustrations of these four species are provided.

The genus Peromitra Enderlein is a small group of phorid flies, including two European parasitic species known to parasitize larval bibionid flies. In this study, specimens of the Peromitra species collected from South Korea are examined morphologically on the basis of characteristics on ocellar region, leg chaetotaxy and hypopygium. As a result, four species are described new to science and two species, viz. P. fimbriata and P. multisetalis are newly recorded from South Korea. Photographs of diagnostic characters and a key to males of South Korean species are provided.

Three species belonging to two families of minute-sized spiders, viz, Theridiosoma fulvum (Araneae: Theridiosomatidae), Microdipoena ogatai and Microdipoena shenyang (Araneae: Mysmenidae), were discovered for the first time in Korea. Previously T. fulvum and M. ogatai were known to distribute only in Japan, M. shenyang only in China. All former records of Microdipoena jobi from Korea are misidentifications of M. shenyang. Detailed descriptions and photographs of three species are provided.

Valgus Kolbe, 1909 is a small genus of Cetoniinae, with 20 described species worldwide. In Korea, only one species, Valgus koreanus Sawada, have been recorded. Species of this genus have been known that they are commonly associated with termite colonies. They feed on the wall of termite burrows in logs or standing dead trees. In this study, we report a new species of this genus, Valgus gwangneungensis sp. nov.. We provide a key to the species of Valgus, description of the new species and photographs of habitus and male aedeagus.

Nemophora Hoffmannsegg, 1798 is a relatively large group in Adelidae, including about 350 species worldwide. Only 13 species are known to Korean insect fauna up to date. The present study is to report N. ochsenheimerella, which is new to Korea. N. ochsenheimerella is externally similar to N. wakayamensis but can be distinguished by having characters in male genitalia as follows: cucullus longer than N. wakayamensis and N. ochsenheimerella has two rows of curnus consisting of numerous minute spines.

The genus Anaclasiger which is one of the myrmecophilous beetle (Clavigeritae) was described by Raffray in 1890 with the type species, A. sinuaticollis. Since then, only one species, A. zhudiae, had been added in this genus. The former species has known to distribute in Singapore (type locality), Taiwan (Raffray, 1914), Malaysia (Nomura & Idris, 2005), Thailand and Japan (Nomura et al., 2006), and the latter has been reported only in China (Yin et al., 2012). During specimens research of Korea National Arboretum, we were recognized one species, A. sinuaticollis, collected by pitfall trap in Mt. Geombong. Therefore, we are going to report this unrecorded genus and species for the first time from Korea. Both the information of the species including diagnosis, habitus and male genitalia, and that of the genus distribution on the map are going to be provided.

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 family Anamorphidae Strohecker is a beetle family that comprises about 170 species worldwide. This family was traditionally considered as a subfamily of the family Endomychidae Leach because of their similar appearance, but a phylogenetic study revealed it is a separate family. The adults of this family can be distinguished from endomychid species by possessing a tentorium with corpotentorium and separated anterior arms, mesocoxal cavities being broadly closed by meso- and metaventrites, and others. Although more than 20 species have been reported in East Asia, this family has never been reported in Korea. In this study, the family Anamorphidae Strohecker and its 5 species of 3 genera, Bystodes kidoi Sasaji, Bystodes sp.1, Bystodes sp.2, Dexialia hiranoi Narukawa, Idiophyes sp., are reported for the first time in Korea. Illustrations of habitus and diagnostic characters of each species are provided.

This research introduces the subfamily Catotrichinae to the South Korean fauna for the first time. Within the globally recognized 6,651 Cecidomyiidae species, only ten are categorized under the Catotrichinae subfamily. Notably, this subfamily, which ingests fungi during larval development, is among the most primordial lineages of the Cecidomyiidae, both in morphological and molecular terms. The species Catoricha nipponensis of Catotrichinae was newly observed in Yeongwol, Gangwon-do, in October 2021. It was recorded for the first time in Korea, with its holotype initially collected in Honshu, Japan, in November 1923. This study provides the diagnosis, photographs of distinguishing characteristics, and the DNA barcode sequences for Catotricha nipponensis. 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 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.

Neomyrhessus Minkina, 2024, is a rare genus comprising six species, recently erected from Myrhessus Balthasar, 1955 for N. nanjingensis. To date, all six species have been reported in East Asia, with five from Japan and one from China. In this study, the genus Neomyrhessus is recorded for the first time in South Korea, with the discovery of a new species Neomyrhessus coreanus sp. nov. Description, illustrations of morphological characters, and habitat information for a new species are provided.

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.

The genus Helictes is a small group of the subfamily Orthocentrinae, comprising 11 species from worldwide, most species from the Palaearctic region, four species from the Nearctic, and two species from the Neotropical region. This subfamily is wide morphological variation between genera but most are readily recognizable as orthocentrines. They are generally small sized, clypeus strongly convex and malar space long. Among them, this genus is reported for the first time from South Korea. In this study, description, photographs of diagnostic characterists are provided.

The genus Priopoda is a small group of the subfamily Ctenopelmatinae, comprising 22 species from worldwide, 10 species from the Eastern Palaearctic and 13 species from the Oriental region. This species and genus are report for the first time from South Korea. The Ctenopelmatinae comprises one of the two major radiations of parasitoids of sawflies. The approximately 1,350 species have been reported in 105 genera and nine tribes. In this study, diagnoses and photos of four unrecorded species from South Korea are provided.

The family Cryptophagidae Kirby (Coleoptera: Cucujoidea) comprises minute beetles, with approximately 800 described species within about 50 genera worldwide. Most members of this family are found in moldy environments and feed on fungal spores and hyphae. The Korean cryptophagid fauna is poorly known, consisting of 22 species belonging to 8 genera. In this study, seven species of Cryptophagidae reported for the first time in Korea: Atomaroides ussurica (Lyubarsky), Cryptophagus micaceus Rey, Cryptophagus pumilus Reitter, Cryptophagus zonatus Lyubarsky, Henoticus pilifer Reitter, Micrambe (Micrambinus) bimaculata (Panzer), and Serratomaria vulgaris Sasaji. Illustrations of habitus, male genitalia, and collection localities of these seven species are provided.

The jewel beetle, Trachy dilaticeps Gebhardt, 1928 has been known to occur in Japan, China, Taiwan, and Vietnam hitherto. This species is typically distributed in Oriental region. In the case of Palaearctic region, it has only been documented in Japan (Kyushu). In this study, we report T. dilaticeps for the first time from Korea, along with its diagnostic characters. Ecological and distributional information is also provided herein.