The family Cerylonidae Billberg, 1820 was originally made up of five subfamilies (Ceryloninae, Euxestinae, Loeblioryloninae, Murmidiinae, Ostomopsinae). However, recent phylogenetic study (Robertson et al., 2015) has reclassified the Euxestinae and Murmidiinae subfamilies as independent families. As a result, the family Cerylonidae now consists of three subfamilies (Ceryloninae, Loeblioryloninae, Ostomopsinae), comprising 38 genera and around 400 species worldwide (Bi and Alekseev, 2021).

The genus ThyroderusSharp, 1885 of the subfamily Ceryloninae Billberg, 1820 includes 9 species worldwide and a single species, Thyroderus porcatusSharp, 1885, from the East Palearctic, Japan, and Taiwan (Ślipiński, 1988, 1990, 2007;Hu et al., 2024). Adults are known to be mycophagous, mainly inhabiting dead wood and leaf litter, with some found in termite nests (Iwata and Banno, 1995).

In this study, T. porcatusSharp, 1885 is recorded as the second cerylonid species in the Korean fauna. Habitus images, diagnostic characters, description, and a distributional map are provided.

Materials and Methods

Twelve specimens were collected by sifting leaf litter, soil, dead wood, and flight interception trap in forest. All specimens were deposited in the Insect Collection of Chungbuk National University (CBNUIC). For detailed characters, two males and one female were dissected and mounted on microscope slides in Euparal solution (Hanley and Ashe, 2003).

Detailed character images were captured using a Sony ILCE- 7RM3 mirrorless camera equipped with 10X/20X Mitutoyo Plan Apo Objectives. These images were stacked and retouched using Zerene Stacker version 1.04. The distribution map was generated, and collection localities were marked using QGIS version 3.36.0 ‘Maidenhead’ (QGIS, 2024).

Systematic Accounts

Family Cerylonidae Billberg, 1820

Subfamily Ceryloninae Billberg, 1820

GenusThyroderusSharp, 1885 곰보애고목벌레속(신칭)

ThyroderusSharp, 1885: 82. Type species: Thyroderus porcatusSharp, 1885.

= DolosusDajoz, 1963: 91. Type species: Dolosus leleupiDajoz, 1963 (as subgenus Ślipiński, 1982: 56).

Thyroderus porcatusSharp, 1885 곰보애고목벌레(신칭) (Fig. 1-3)

Thyroderus porcatusSharp, 1885: 82 (original description, habitus).

Diagnosis. This species is easily identified by pronotum with irregular membranous area on each side, and hypomeron with exhibit posteriorly wide and limited large antennal cavities (Fig. 1, 3A, B).

Description. Body length 1.27-1.61 mm, body shape elongated oval, color reddish brown, body covered clavate or short rounded yellow setae, with sparse sharp setae, irregularly scattered reticular surface (Fig. 1).

Head. Deflexed, punctate surface with long or short yellow clavate setae (Fig. 2A, B), clypeus broad with rounded front, gular and gena reduced; occiput clearly separate by horizontal line; eyes well-developed, convex, frontal margin with antennal socket (Fig. 2B), antennal groove under antennal socket and eyes under margin (Fig. 1C, 2B); antennae 8 segmented, sharp setae, scape swollen, pedicel length near twice of flagellomere 1, flagellomere 1-5 short, flagellomere 6 clubbed (Fig. 2C); maxillary palpi with elongate brush-shaped lacinia and galea (Fig. 2D); mandible truncate tip incisor with lacina mobilis elnongate (Fig. 2E); hypopharynx lateral margin bears three seta (Fig. 2F); paramentum anteriorly narrowed with swollen labial palpi with membranous ligula (Fig. 2G).

Thorax. Pronotum convex, with rounded smooth lateral margin, punctate surface with dense clavate setae with sparse sharp setae (Fig. 1A, 3A, B), each side with pair membranous area (Fig. 1, 3A, B); prosternum with broad anterior margin covered ventral head (Fig. 1B, 2A, B), weakly rounded prosternal process (Fig. 1B, 3B), hypomeron anterior with antennal groove, posterior limited large antennal cavities (Fig. 3B), procoxal cavity small, posteriorly open (Fig. 3B); mesosternum short with large mesocoxal cavities with weakly midleg groove on basolateral (Fig. 3C); metasternum basolateral dent receive hindleg (Fig. 1C, 3C), metasternal epimeron smooth surface connects with ventrite to form a hindleg groove (Fig. 3C, D).

Abdomen. (Fig. 3D) Longer than wide, metacoxal cavity broad, ventrites irregularly punctate surface with short sharp setae, ventrite 5 lateral margin with long single setae, posterior part serrated.

Legs. Trochanter with single large yellow to white setae, similar setae with each tarsomere 1 (Fig. 1B, 3E-G), sharp setae, tibia apical setae dense (Fig. 1A, B, 3E-G), femurs mid convex (Fig. 3E-G), protibia enlarged apically with apical outer margin with weak tooth (Fig. 3E), tarsomere 4-4-4, tarsomere 1 longer 2 3, tarsomere 4 longer other tarsomeres, tarsal claw simple (Fig. 3E-G).

Elytra. (Fig. 3I) Elongate, elytral epipleura complete, large ridge in immediately anterior metacoxal (Fig. 1C, 3C, D, I), 10 rows of regular punctures, 10th row done at the elytra ridge, slightly convex every 2 rows with clavate setae distributed irregularly with short setae distributed between each punctate.

Wing. (Fig. 3H) Hindwing well-developed subcoastal and media vein without anal vein, outer margin with fine setae.

Male genitalia. (Fig. 3J-L) Median lobe slender simple, curved in lateral view (Fig. 3J), yellowish brown, darker middle part, membranous near dorsal tip (Fig. 3J, K).

Material examined (n=12, 5♂♂7♀♀). Korea: 1♂ (1♂ 95% slide mounted /CBNUIC) Gyeongbuk Prov. 117-74, Seonghyeon-gil, Yongmun-myeon, Yecheon-gun, 20.VI~09. VII.2021, 36°40'24.0"N 128°24'38.0"E, 183 m, FIT, U.-J. Byeon; 1♂ (1♂ dry speciemens /CBNUIC) Gyeongbuk Prov. Naegiri, Yongmun-myeon, Yecheon-gun, 20.VI~09.VII.2021, 36°42' 45.0"N 128°23'04.0"E, 407 m, FIT, U.-J. Byeon; 1♂1♀ (1♂1 ♀ 95% EtOH in tube /CBNUIC) Gyeongnam Prov. Suyabang Island, Suyabangsup-gil, Hacheong-myeon, Geoje-si, 23.VIII. 2023, 34°52'05.6"N 128°36'04.9"E, 29 m, sifting leaf litter & soil, J.-W. Kang, S.-H. Choi, T.-Y. Jang; 1♀ (1♀ 95% EtOH in tube /CBNUIC) Gyeongnam Prov. Suyabang Island, Suyabangsup- gil, Hacheong-myeon, Geoje-si, 23.VIII.2023, 35°01'10.0"N 128°38'21.0"E, 29 m, sifting soil & deadwood debris, J.-W. Kang, S.-H. Choi, T.-Y. Jang; 2♂♂3♀♀ (1♂3♀♀ 95% EtOH in tube / 1♂ slide mounted /CBNUIC) Gyeongnam Prov. Suyabang Island, Suyabangsup-gil, Hacheong-myeon, Geojesi, 23.VIII.2023, 34°52'00.8"N 128°36'48.5"E, 61 m, sifting soil & deadwood debris, J.-W. Kang, S.-H. Choi, T.-Y. Jang; 1 ♀ (1♀ 95% EtOH in tube /CBNUIC) Gyeongnam Prov. Mt. Gyeryong, Geoje Island, Gyeryongsansup-gil, Geoje- myeon, Geoje-si, 23.VIII.2023, 34°51'20.8"N 128°37'44.8"E, 274 m, sifting soil & herbal debris, U.-J. Byeon, J.-I. Shin, G.-Y. Ryu; 1♀ (1♀ slide mounted /CBNUIC) Jeonnam Prov. Mt. Chilac, Ye-ri, Heuksan-myeon, Sinan-gun, 18.IV.2021, 34°40'41.1"N 125°26'12.4"E, 135 m, sifting leaf & soil litter, J.-W. Kang.

Distribution. Japan, Taiwan, Korea (Fig. 4).

Comment. Sexual dimorphism is not easily discernible in this species, so the genitalia must be examined for sexual identification. The presence of inappropriate mouth parts for chewing (Fig. 2A, D, E), the presumed presence of mycangia structures in the exoskeletal cavities (Grebennikov and Leschen, 2010), and the observation of cases in termite nests (Iwata and Banno, 1995), suggest that T. porcatus may be a mycophagous species.