Introduction
Dryomyzidae Schiner, 1862 is a small family of acalyptrate flies, comprising 31 described species in seven genera worldwide (Mathis and Sueyoshi, 2011;Ozerov and Krivosheina, 2022). Members of the family are mainly distributed in the Holarctic region, and adults are usually found in humid forests or around decaying organic substrates, including carrion, excrement, fungi, and other decomposing materials (Mathis and Sueyoshi, 2011;Ozerov and Krivosheina, 2022). In South Korea, the family has been poorly studied, and only five dryomyzid species have been recorded to date (KSAE and ESK, 2021).
Paradryomyza Ozerov, 1987 comprises only five species worldwide, and most species have been documented from limited geographic regions, based on relatively few records (Mathis and Sueyoshi, 2011;Ozerov, 2017;Ozerov and Krivosheina, 2022). In Korea, Paradryomyza spinigera Ozerov, 1987 is the only recorded species in the genus, but its occurrence from the Korean Peninsula, particularly North Korea, was briefly mentioned in a Taiwanese checklist (Papp, 2005); however, no detailed taxonomic account, diagnostic photographs, or DNA barcode data based on Korean specimens have been provided to date.
In the present study, we provide taxonomic information on Korean specimens of P. spinigera, including description, images of external and internal morphology, including terminalia, and mitochondrial cytochrome c oxidase subunit I (COI) barcode sequences. We also compare the South Korean specimens with other regional records previously published and COI barcode data publicly available in order to discuss morphological and barcode variation within the species currently identified as P. spinigera.
Materials and Methods
The morphological characters of Paradryomyza spinigera were examined under a Leica S9E stereomicroscope (Leica Microsystems, Wetzlar, Germany) at magnifications ranging from 6× to 55×. The morphological terminology mainly followed Cumming and Wood (2017), but we also followed Ozerov and Krivosheina (2022) for genitalic terminology that was not described by Cumming and Wood (2017).
A series of raw images (≥50 shots per specimen) were captured using a Dhyana 400DC camera (Tucsen Photonics, Fuzhou, China) mounted on a Leica Z16 APO stereomicroscope (Leica Microsystems, Wetzlar, Germany). Genitalia photographs were taken with a Dhyana 400DC camera (Tucsen Photonics, Fuzhou, China) mounted on a Leica DM3000 LED microscope (Leica Microsystems, Wetzlar, Germany). The images were stacked using Helicon Focus software v8.2.18 (Helicon Soft Ltd., Kharkiv, Ukraine). Minor adjustments to levels and background clean-up were made using Adobe Photoshop 26.0.0 (Adobe Inc., San Jose, CA, USA); no alteration was made to any morphological feature in the images.
Total genomic DNA was extracted from the legs using a DNeasy Blood & Tissue Kit (QIAGEN, Hilden, Germany), following the manufacturer’s protocol. Nine specimens were sequenced for mitochondrial cytochrome c oxidase subunit I (COI) barcoding. The standard barcode region (658 bp) was amplified using primers LCO1490/HCO2198 (Folmer et al., 1994). PCR was performed using SolgTM 2X Taq PCR Pre-Mix (SolGent, Daejeon, South Korea) according to the manufacturer’s instructions. Amplicons were purified using the QIAquick PCR Purification Kit (QIAGEN, Hilden, Germany) and sequenced by Macrogen Inc. (Seoul, Korea).
For phylogenetic analysis, we downloaded the barcode sequences of 34 individuals of Dryomyzidae and four individuals of Conopidae Latreille, 1802 (as outgroups), which are publicly available from the BOLD Systems (www.boldsystems.org; as of May 2026) and NCBI (www.ncbi.nlm.nih.gov; as of May 2026). The sequences were assembled and aligned in Geneious Prime v2026.0.2 (Biomatters, Auckland, New Zealand). Pairwise p-distances were calculated in MEGA11 (Tamura et al., 2021) using all codon positions, with transitions and transversions included and sites with gaps or missing data excluded by complete deletion. Maximum likelihood (ML) analysis was conducted using IQ-TREE v3.0.1 (Wong et al., 2026) under the GTR+I+G nucleotide substitution model. Branch support was assessed using 10,000 ultrafast bootstrap replicates (Hoang et al., 2018).
Taxonomic Accounts
Family Dryomyzidae Schiner, 1862
Genus ParadryomyzaOzerov, 1987
ParadryomyzaOzerov, 1987: 38. Type species: Odontomera setosaBigot, 1886: 386, by original designation.
Diagnosis. The genus Paradryomyza can be distinguished from related dryomyzid genera by the following characteristics [modified from Ozerov and Krivosheina (2022)]: (1) Head with a pair of well-developed outer vertical setae (Fig. 1A, E); (2) arista with short hairs along its entire length (Fig. 1A, B, E, F); (3) scutum with 2 pairs of dorsocentral setae (Fig. 1A, E); (4) acrostichal setae absent (Fig. 1A, E); (5) scutellum with two pairs of setae (Fig. 1A, E); (6) wing tinged brownish, lacking dark markings (Fig. 1A, B, E, F); (7) vein R1 setulose in apical half dorsally and bare in basal half (Fig. 1C); (8) hind femur bearing two rows of spinules apically on ventral surface (Fig. 1D); (9) surstylus triangular, strongly broadened basally and tapering toward the apex, covered with hairs (Fig. 2A, B); (10) ventromedial process thin and curved (Fig. 2A); and (11) female abdominal tergites 6 and 7 spinulose (Fig. 2D).
Paradryomyza spinigera Ozerov, 1987 (Fig. 1;Fig. 2;Fig. 3)
Paradryomyza spinigeraOzerov, 1987: 39. Type locality: Zeya Town, Amur Oblast, Russia; type depository: Zoological Museum, Moscow Lomonosov State University, Moscow, Russia.
Paradryomyza spinigera: Ozerov, 1999: 554 (Russia, key); Mathis and Sueyoshi, 2011: 207-223 (World catalog); Ericson and Hellqvist, 2013: 2-3 (Sweden, new record); Kahanpää and Winqvist, 2014: 269 (Finland, checklist); Hagenlund and Kvifte, 2015: 198, 201 (Norway, new record); Silfverberg, 2017: 199 (Finland, faunal update); Zinchenko, 2021: 205-206 (Russia, distributional records); KSAE and ESK, 2021: 455 (South Korea, checklist); Ozerov and Krivosheina, 2022: 323-325 (Russia, review); Jia et al., 2022: 326-329 (China, new record).
Diagnosis. This species may be distinguished from congeners by the combination of the following characters [modified from Jia et al. (2022) and Ozerov and Krivosheina (2022)]: (1) frons usually with black or blackish spot in front of fronto-orbital setae (Fig. 1A, E); (2) occiput without black marking in upper half (Fig. 1A, E); (3) the distance between two genal setae wider (Fig. 1B, F); (4) palpus almost completely dark brown or black (distal half dark brown or black and basal half yellowish brown in South Korean specimens) (Fig. 1B, F); (5) katepisternum covered with silvery white hairs (Fig. 1B, F); (6) legs yellow in ground color (Fig. 1B, F); (7) hind femur with 4-10 stout spinules apically on ventral surface (Fig. 1D). Male genitalia: (8) ventromedial process crooked at apex in lateral view (Fig. 2A); (9) surstylus slender and straight on apical half in lateral view (Fig. 2A).
Description of South Korean specimens (Figs. 1, 2). Male and Female. Body Length: Male. 4.05-7.20 mm; Female. 4.25-7.50 mm. Head (Fig. 1A, B, E, F): ocellar triangle dark brown to black; 1 inner vertical seta; 1 outer vertical seta; 1 lateroclinate fronto-orbital seta; frons yellowish brown with black or blackish spot in front of fronto-orbital setae; 1st flagellomere oval-shaped with yellowish brown to brown; arista plumose with distal two-thirds black to dark brown and basal one-third yellowish brown; gena brownish yellow with 2 genal setae; the distance between two genal setae as wide as the length of genal setae; occiput yellowish brown without black marking in upper half; palpus distal half dark brown or black and basal half yellowish brown. Thorax (Fig. 1A, B, E, F): scutum yellowish brown to brown with dark brown to black stripe medially; 1 postpronotal seta; 1 posthumeral seta; acrostichal setae absent; 2 postsutural dorsocentral setae; 1 postsutural supra-alar seta; 2 notopleural setae; 2 postalar setae; pleural sclerite yellowish brown; katepisternum covered with silvery white hairs; 1 + 2 katepisternal setae; scutellum yellowish brown to brown with 2 scutellar setae. Legs (Fig. 1A, B, E, F): femora and tibiae almost entirely yellowish brown; tarsi dark brown to black; apex of fore femur brown; apex of mid femur brown; apex of hind femur brown; hind femur with 4-10 stout spinules apically on ventral surface; apex of hind tibia dark brown to black. Wing (Fig. 1A-C, E, F): vein R1 setulose in apical half dorsally and bare in basal half; crossveins r-m and dm-cu with or without weak infuscation. Abdomen (Fig. 1A, B, E, F): tergites and sternites yellowish brown in ground color; tergites 1-4 covered with black pruinosity entirely and black band on posterior margin; tergite 5 covered with black pruinosity medially. Male Genitalia (Fig. 2A-C): epandrium subrectangular in lateral view with setae sparsely; ventromedial process slightly curved upwardly in lateral view; hypandrium flask-shaped in lateral view; pregonite with 3 setae in lateral view; distiphallus as long as phallapodeme with hairs densely covered its entire length (degree and direction of curvature may vary among specimens, possibly due to preparation artifacts). Female Terminalia (Fig. 2D): tergites 6 and 7 yellowish brown to brown; long setae along posterior margin of tergite 6 with short setae; tergite 7 with short spine-like setae sparsely.
Material examined. South Korea: 1♀, Gangwon-do, Goseong-gun, Sudong-myeon, Hyangrobong, N38°16′19.10″ E128°19′23.70″ (Malaise Trap), 27.V-18.VII.2019, S.-J. Roh et al.; 1♂, ditto, 18.VII-9.VIII.2019, S.-J. Roh et al.; 1♂, 1♀, Gangwon-do, Hongcheon-gun, Nae-myeon, Mt. Gachilbong from Sambongyaksu to 1240 m peak, 2.VI.2007, H.-S. Lee et al.; 2♂, Gangwon-do, Hongcheon-gun, Nae-myeon, Mt. Gyebangsan Unduryeong, N37°43′41″ E128°27′55″, 15.VII.2010, S.-W. Suk, Y.-B. Lee, and H.-S. Lee; 3♂, Gangwon-do, Wonju-si, Panbu-myeon, Seogok-ri, Mt. Baegunsan from Yongsu-gol to 1087.1 m peak, N37°14′59″ E127°57′46″, 23.VI.2016, C.-O. Kim and W.-R. Ha; 2♂, Gangwon-do, Yanggu-gun, Bangsan-myeon, Gobangsan-ri, Dutayeon, N38°13′23.89″ E127°58′28.58″, 24.IX-27.X.2020 (Malaise Trap), Y.-H. Park et al.; 1♂, Gyeongsangbuk-do, Yeongyang-gun, Irwol-myeon, Mt. Irwolsan from Iljabong to woljabong, N36°48′20″ E129°6′17″, 26.VI.2014, Y.-B. Lee and S.-S. Euo; 2♂, 1♀, ditto, 15.VII.2014, Y.-B. Lee et al.; 1♂, Gangwon-do, Jeongseon-gun, Imgye-myeon, Gamok-ri, Baekbongryeong 794 m, N37°32′32.74″ E128°57′52.37″ (Malaise Trap), 15.IX-19.X.2020, Y.-H. Park et al.; 1♀, Gangwon-do, Pyeongchang-gun, Bongpyeong-myeon, Jinjo-ri, Mt. Cheongtaesan 858 m, N37°31′58.03″ E128°18′26.79″ (Malaise Trap), 1.VII-18.VIII.2020, Y.-H. Park et al.; 4♂, 2♀, ditto, 15.IX-19.X.2020, Y.-H. Park et al.
Distribution. South Korea, China, Finland, Norway, Russia, and Sweden.
DNA barcode. The sequences have been deposited in NCBI (GenBank Accession No. PZ447478-PZ447486).
Remarks. The South Korean specimens examined here agree well with Ozerov’s (1987) original description of Paradryomyza spinigera and with the Russian review of the species by Ozerov and Krivosheina (2022). Morphological differences between the South Korean specimens and previously published Chinese and Swedish records are discussed in detail below.
Results and Discussion
Paradryomyza spinigera was originally described from the Russian Far East, with the type locality in Amur Oblast, Russia (Ozerov, 1987). Since its original description, the species has been recorded from northern Europe and East Asia. However, comparison of the original description from the Russian Far East (Ozerov, 1987), subsequent records from Sweden (Ericson and Hellqvist, 2013) and China (Jia et al., 2022), and the South Korean specimens examined in the present study revealed several morphological discordances, suggesting that the current concept of this species may include geographically structured variation or possibly more than one taxon.
The Korean specimens of the present study are congruent with the original description of P. spinigera, in most diagnostic characters including the presence of two dark frontal spots, scutal chaetotaxy with 1 posthumeral seta, 1 postsutural supra-alar seta, and two dorsocentral setae, 1 + 2 katepisternal setae, sparse whitish hairs on the katepisternum, setulae on the apical half of vein R1, and weak infuscation around crossveins r-m and dm-cu (Table S1). A slight variation was observed in palpus coloration: Ozerov (1987) described the palpus as almost entirely black, whereas in the South Korean specimens only the distal half is blackish and the basal half is yellowish brown.
The Chinese specimens reported by Jia et al. (2022) appear to differ from both the original description and the Korean specimens in several characteristics. In the diagnosis of Ozerov and Krivosheina (2022), Paradryomyza is characterized by two pairs of dorsocentral setae and vein R1 setose dorsally in the apical half and bare in the basal half. By contrast, Jia et al. (2022) described the Chinese specimens as having only one dorsocentral seta and vein R1 without dorsal setulae along its entire length (Table S1). If accurate, these character states conflict not only with the original description of P. spinigera but also with the current generic diagnosis. Therefore, the identity of the Chinese specimens appears questionable.
Other differences in the Chinese specimens include the absence of dark frontal spots, the absence of a presutural supra-alar seta, and the presence of four katepisternal setae (Table S1). The male terminalia illustrated by Jia et al. (2022) also appear to differ from those of the South Korean specimens, particularly in the shape of the ventromedial process in lateral view. However, this difference should be interpreted cautiously because comparison based only on published images may be affected by specimen orientation, dissection, and mounting condition.
The Swedish specimens reported by Ericson and Hellqvist (2013) appear to be closer to the original description in several characteristics, including the dark palpus, a faint dark spot near the orbital seta, dorsally darkened antenna, dark median longitudinal stripe on the scutum, black tarsi, and setulae on the outer part of vein R1. Nevertheless, they differ from the original description in having both pale and dark hairs on the katepisternum and unshaded wing crossveins (Table S1). These differences may represent intraspecific variation, but they also suggest that the morphological limits of P. spinigera require further assessment.
The COI barcode analysis revealed a clear geographic structure among sequences currently identified as P. spinigera. All available sequences of P. spinigera formed a robustly supported clade, whereas the South Korean sequences formed a distinct subclade within it (Fig. 3). The Chinese and Finnish sequences were placed as a sister group of the South Korean subclade (Fig. 3). The mean interclade p-distances between the South Korean clade and the Chinese and Finnish clades were 0.03681 and 0.03374, respectively, whereas the distance between the Chinese and Finnish clades was only 0.00307 (Table 1). This pattern is consistent with the morphological differences observed among regional specimens. Nevertheless, the COI data alone do not justify describing the South Korean population as a separate species, especially because COI barcodes are not yet available from the type locality or from specimens collected near the type locality.
Therefore, we provisionally identify the South Korean specimens as P. spinigera because they agree more closely with the original description and with the generic diagnosis of Paradryomyza than do the Chinese specimens reported by Jia et al. (2022). Further taxonomic study is needed to clarify whether the observed differences represent intraspecific variation, geographic differentiation, misidentification, or overlooked species-level diversity within specimens currently identified as P. spinigera. Direct examination of the holotype and additional specimens from the type locality and adjacent areas in Amur Oblast is essential. In addition, COI barcodes should be obtained not only from the type locality but also from geographically intervening regions across northern Eurasia and northeastern Asia. Such intermediate geographic sampling is necessary to determine whether the South Korean, Chinese, and northern European lineages represent distinct clades, a continuous pattern of geographic variation, or artifacts of limited sampling.












KSAE