Until now, only two species of Dichaetomyia Malloch have been recorded in the Korean fauna. In this study, we report two unrecorded species for the first time in Korea. External photographs, key to Korean species and taxonomic information are presented herein.

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.

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 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.

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 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 genus Caenoscelis C. G. Thomson (Coleoptera: Cryptophagidae: Cryptophaginae) comprises approximately 30 species in the world, primarily distributed in the Holarctic region. Although 15 Caenoscelis species occur in the Palearctic region, only a single species, Caenoscelis sibirica Reitter, has been documented in Korea. In this study, Caenoscelis koreanus sp. nov. is described, and Caenoscelis ferruginea (C. R. Sahlberg) is reported for the first time in Korea. The new species can be distinguished from other Caenoscelis species by their subquadrate antennomere 10, fully developed hind wings, and male genitalia with subacute parameres and indistinctly separated lateral lobes. Illustrations of habitus, diagnostic characters, and a distribution map of Korean Caenoscelis species are provided.

The genus Grapholita Treitschke, 1829 is a complex group belonging to the tribe Grapholitini of the subfamiliy Olethreutinae, due to their similar characteristics among the species. The genus comprises about 150 described species worldwide. The majority of described species occur in the Holarctic region. To date, eight species of Grapholita have been reported from Korea. The genus contains several notorious pests such as G. dimorpha Komai and G. molesta (Busck). Among them, G. inopinata has been doubtful in distribution. This study aim to optimize species specific sex pheromone composition/amount and establish the distribution of the pest species of the genus Grapholita in Korea.

The genus Stenotothorax is reported for the first time in the Korean Peninsula. While working on Korean Aphodiinae, we identified Stenotothorax hibernalis (Nakane & Tsukamoto) from the Goseong-gun, Gangwon Province. This species was found in the northern region of South Korea. A key to Aphodiini genera in Korea, habitus photographs, and illustrations of diagnostic characters are provided to facilitate identification.

The genus Megastylus is a moderate group of the subfamily Orthocentrinae, comprising 38 species in two subgenera from worldwide. The subfamily Orthocentrinae is a high proportion of the genera are cosmopolitan in distribution. Orthocentrines are known as almost solitary koinobiont endoparasitoids. We report this genus for the first time from South Korea. In this study, descriptions of some new species, photographs of diagnostic characterists are provided.

The genus Hypsopygia was established by Hübner, 1825, with type species Phalaena costalis Fabricius, 1775. Hypsopygia is characterized by the elongated uncus and valva, and pointed saccus in the male genitalia. It consists of 105 described species (Nuss et al., 2003–2024) in the world, and 11 species have been recorded in Korea (Kim & Paek, 2020; Shin et al., 2023). In this study, we reported one newly recorded species in Korea. Illustrations of adults provided, with information of host plants of all examined species.

The genus Olethreutes, established by Hübner in 1822, is based on the type species Phalaena arcuella Clerk, 1759. Olethreutes is one of the largest group within the family Tortricidae, with more than 130 species worldwide. As of now, about 31 species of the genus Olethreutes have been reported in the Korean peninsula. The proposes of this study is to describe one new species, with three similar species form Korea.

Mantidflies or Mantid lacewing (Mantispidae) is a morphologically interesting group of Neuroptera. This group is a general predator of arthropods and is equipped with raptorial forelegs similar to praying mantis. In Korea, only three species, Climaciella quadrituberculata, Mantispa harmandi, and Mantispilla japonica, are recorded until now. Here we report Genus Necyla and Necyla formosana, new records in Korea. We provide diagnostic character and photos of adult and genitalia.

The Genus Psectra is a small group of Hemerobiidae, and Psectra diptera is one of the rare and attractive species in this group because of hindwing variation. They are well known to have their hindwing reduced, similar to flies, depending on their habitat environment. We report Genus Psectra and Psectra diptera, new records from Korea. We provide brief descriptions and photos of adults and genitalia.

To assess the accuracy of species delimitation in the genus Aphaenomurus Yosii, we conducted a comparative micro-morphological study and molecular analysis using two mitochondrial (COI, 16S) and two nuclear genes (18S, 28S) on 118 specimens from 24 localities. The results showed that the morphological characters of A. vicinus and A. interpositus, as presented in the original description, were intermixed in phylogenetic lineages within the genus and did not form independent lineages. Furthermore, there were enough differences among Aphaenomurus individuals to be considered as morphologically distinct species (Th. III is 1+1 or 2+2, Abd. I is 2+2 or 3+3, Abd. II is 2+2 or 3+3), but they do not form an independent lineage. Molecular and morphological analyses have determined that A. vicinus and A. interpositus are the same species, exhibiting morphological variation in dental spines formula, claws, chaetotaxy, and other features. Additionally, the genus Aphaenomurus forms a monophyletic clade, which is further divided into several lineages within the genus. No morphological differences were observed to distinguish these lineages. This cladistic divergence is attributed to heteroplasmy, which is supported by previous studies that have suggested the possibility and problems of heteroplasmy in Collembola, and by the high genetic distances between individuals in the mitochondrial genes of Aphaenomurus.

The genus Argyresthia Hübner, [1825] of the family Argyresthiidae is known to comprise over 150 species worldwide. Among them, more than 70 species are recognized in the Palearctic region. The Korean fauna of the genus Argyresthia includes 11 described species to date. In this study, we report three species of the genus Argyresthia for the first time in Korea: A. brockeella (Hübner, [1813]), A. longalbella Liu, Wang & Li, 2017, and A. mala Liu, Wang & Li, 2017. All available information, images of adults and genitalia for species are provided.