Most species of Silvanidae Kirby, 1837 (Coleoptera: Cucujoidea) are characterized by small-to-medium size, a flattened, elongated body, and often feature a distinctive lateral margin of the prothorax (Halstead, 1993). This family includes approximately 500 described species across 58 genera worldwide, with the highest abundance at both the generic and species levels in the tropical region (Thomas and Leschen, 2010). Although the biology and immature stages of most silvanids remain unknown, they primarily appear to be mycophagous (Thomas, 2002). However, certain species of the genera AhasverusGozis, 1881, CathartusReiche, 1854, NausibiusLentz, 1857, and OryzaephilusGanglbauer, 1899, are notable pests of stored grains and grain products, with well-documented biology (Thomas, 1993).

AhasverusGozis, 1881 of the subfamily Silvaninae is a New World genus containing nine described species (Halstead, 1993). These beetles have been found under bark, in the nests of eastern meadow vole (Mammalia: Rodentia) and Polistes wasps (Hymenoptera: Vespidae), in sifted sphagnum marsh, light traps, rotting flowers and cocoa husks, and in piles of decaying soybeans (Halstead, 1993;Nelson, 1968;Thomas, 1993). Two Ahasverus species, A. advena (Waltl, 1834) and A. excisus (Reitter, 1876), are known in the Palearctic region. However, no records in Korea (Halstead et al., 2007;NIBR, 2023). A. advena occurs in various moldy foodstuffs such as cereal products, dried fruits, grains, herbs, oil seeds, spices (Sengupta and Pal, 1996).

The genus PsammoecusLatreille, 1829 (Brontinae: Telephanini) is the second-largest silvanid genus, including 85 described species (Thomas and Leschen, 2010;Yoshida and Reid, 2023). The distribution of this genus was previously restricted to the Old World until Thomas and Yamamoto (2007) reported P. trimaculatusMotschulsky, 1858 in Brazil. These beetles are usually found in plant substrates, such as bushes, dry cut grass, flowers, haystacks, and leaf garbage (Sengupta and Pal, 1996). Additionally, immature stages of several Psammoecus species were reported by Pal (1985) and Yoshida and Hirowatari (2015). Twenty-three Psammoecus species are known in the Palearctic region, and two species, P. fasciatusReitter, 1874 and P. triguttatusReitter, 1874 are recorded in Korea (Baena et al., 2020;Halstead et al., 2007).

In this study, two silvanid beetle species, Ahasverus advena (Waltl, 1834) and Psammoecus trimaculatusMotschulsky, 1858, are reported for the first time in Korea. Photographs of the habitus, diagnostic characters, and a distribution map for each species are provided.

Material and Methods

A total of 20 specimens, deposited in the Chungbuk National University Insect Collection, Cheongju, Republic of Korea, were examined. Photographs of the habitus were captured using a mirrorless camera (Sony ILCE-7RM3) using a Mitutoyo M Plan Apo 10X objective lens. The abdomen of each species was partially dissected to examine male genitalia. These structures were immersed in 10% KOH solution for 12 hours and mounted on a plastic card with Hempstead Halide® Hoyer’s Slide Mounting Medium, then photographed using an optical microscope (Leica DM1000) with Las version 4.12. Multiple images were stacked using Zerene Stacker version 1.04. The morphological terminology of the genus Ahasverus followed that of Halstead (1993), while the terminology of the genus Psammoecus followed that of Yoshida and Hirowatari (2014). The collection localities were subsequently marked on a map generated using SimpleMappr (Shorthouse, 2010).

Systematic Accounts

Family Silvanidae Kirby, 1837 가는납작벌레과

Subfamily Silvaninae Kirby, 1837 가는납작벌레아과

Genus AhasverusGozis, 1881

Ahasverus Gozis, 1881: 127.

Type species Cryptophagus advenaWaltl, 1834

Diagnosis. This genus shares morphological characters with the genus Cathartus Reiche but can be distinguished by the following combination of characters: antennomere 9 distinctly narrower than 10 (Fig. 1A); prothorax transverse, anterior angle distinctly produced and callosity-like, sterno-pleural suture extending to anterior angle (Fig. 1A); elytra oval (Fig. 1A); metasternum with femoral lines (antennomere 9 weakly narrower than 10; prothorax elongate, anterior angle slightly produced; sterno-pleural suture extending to pronotal sides, far below anterior angle; elytra parallel-sided; metasternum without femoral lines in Cathartus). See more detail diagnosis in Sengupta and Pal (1996).

Ahasverus advena (Waltl, 1834) 곡식가는납작벌레(신칭) (Fig. 1)

Diagnosis. Adults of this species can be distinguished from Ahasverus excisus (Reitter, 1876), the only other Palearctic species, by the following combination of characters: pronotum about 1.7-2.0 times as wide as long, sides slightly constricted near anterior angle (Fig. 1A); pronotal anterior angles obtuse (Fig. 1A); apex of median lobe comparatively narrow (Fig. 1B) (pronotum about 1.9-2.1 times as wide as long, sides strongly constricted near anterior angle; pronotal anterior angles acute; apex of median lobe wide in A. excisus), as also described and figured in Halstead (1993).

Description. See Halstead (1993) for redescription.

Material examined (n=4, 1♂3exx.). 1♂2exx. (1♂ genitalia dissected, point mounted; 2exx. point mounted) Korea: Jeju Island, Donmullae-gil, Aewol-eup, Jeju-si, 21.V.2022, 33°23'55.2"N 126°19'32.6"E, 186 m, sifting soil litter & vegetable debris, T.-Y. Jang, J.-W. Kang; 1ex. (in 95% EtOH) Korea: Jeju Island. 215, Haso-ro, Aewol-eup, Jeju-si, 18.VII.2021, 33°27'46.5"N 126°23'38.8"E, 96 m, sifting soil & corn stem debris, J.-W. Kang, J.-I. Shin.

Habitat. Adults of this species were collected by sifting soil, vegetable debris, and corn stem debris.

Distribution. Cosmopolitan species widely distributed in Europe, North Africa (Canary Islands, Egypt, Libya, Morocco, Madeira Archipelago), and Asia (China, Japan, Russia, Taiwan) (Halstead et al., 2007); Korea (Fig. 3).

Subfamily Brontinae Erichson, 1845

Tribe Telephanini LeConte, 1861

Genus PsammoecusLatreille, 1829

PsammoecusLatreille, 1829: 135.

Type species Notoxus bipunctatusFabricius, 1792CryptaStephens, 1830: 103.

Diagnosis. Within the tribe Telephanini, this genus can be distinguished from other genera by the following combination of characters: Frons without median groove, with pair of distinct lateral grooves (Fig. 2A); elytra without scutellary striole (Fig. 2A) (Karner et al., 2015;Thomas and Nearns, 2008).

Psammoecus trimaculatusMotschulsky, 1858 닮은모래가 는납작벌레(신칭)(Fig. 2)

Psammaechus [sic.] trimaculatusMotschulsky, 1858: 45.

Cucujus incommodusWalker, 1859: 53.

Psammoecus alluaudiGrouvelle, 1912: 409 [synonymized by Karner, 2012: 24].

Psammoecus excellensGrouvelle, 1908: 115 [synonymized by Karner, 2012: 24].

Psammoecus triguttatus Reitter inHirano, 2009: 64-66; Hirano, 2010: 12, 14 [misidentification, see Yoshida and Hirowatari, 2014: 24].

Diagnosis. Adults of this species share morphological characters with Psammoecus labyrinthicus Yoshida & Hirowatari and P. triguttatus Reitter. However, they can be distinguished from these two species by the larger base of parameres (Fig. 2B), whereas the base of the parameres is comparatively narrow in those two species, as described and illustrated by Yoshida and Hirowatari (2014).

Description. See Sengupta and Pal (1996) and Yoshida and Hirowatari (2014) for redescription.

Material examined (n=16, 2♂♂14exx.). (1♂ genitalia dissected, point mounted; 10exx. in 95% EtOH) Korea: Gangwon Prov. Jangjeon-gil, Jinbu-myeon, Pyeongchang-gun, 01.VIII.2023, 37°29'56.8"N 128°32'56.1"E, 384 m, Light trap, Y.-J. Choi, J.-W. Kang, J.-I. Shin, U.-J. Hwang; (1♂ genitalia dissected, point mounted; 4exx. in 95% EtOH) Korea: Jeju Island. 215, Haso-ro, Aewol-eup, Jeju-si, 18.VII.2021, 33°27' 46.5"N 126°23'38.8"E, 96 m, sifting soil & corn stem debris, J.-W. Kang, J.-I. Shin.

Habitat. Adults of this species were collected by sifting soil and corn stem debris and attracted by a light trap with a 250 W metal halide lamp.

Distribution. Japan (Yoshida and Hirowatari, 2014); Taiwan (Yoshida et al., 2018); Mauritius Island, Reunion Island, South Africa, Tanzania, Uganda (Karner, 2014); Italy (Mola and Yoshida, 2019); Russia (Kovalev, 2016); Brazil (Thomas and Yamamoto, 2007); Australia, Bhutan, Fiji, India, Philippine, Madagascar, Malaysia, Myanmar, Nepal, New Caledonia, New Guinea, Samoa, Sri Lanka, U.S.A (Baena et al., 2020); France (Christian, 2023); Korea (Fig. 3).