Journal 
The genus Platydema Laporte & Brullé, 1831 belongs to the tribe Diaperini in the family Tenebrionidae, which contains 281 described species worldwide (Gebien, 1940), with approximately 51 species reported in the Palearctic region (Löbl et al., 2008). The following features characterize members of the Platydema genus: body oval, glabrous, and strongly convex dorsally; head mostly with a pair of straight horns in males and a pair of blunt tubercles in females or rarely absent in males and females (Chûjô, 1982;Jung, 2012).
Most of the Platydema species have become host specific to macrofungi, including Basidiomycetes or mycelina, which are food for the fungivorous tenebrionids (Leschen, 1990;Jung and Lee, 2011). In Korea, Platydema species are usually obligatory inhabitants of perennial and woody bracket fungi. Adults and larvae of fungivorous tenebrionids spend their entire lives in the fruiting bodies of bracket fungi (Jung and Lee, 2011). Ten Platydema species have been previously recorded in Korea (Jung, 2015).
Of these, Platydema takeii Nakane, causes serious damage to wood ear mushroom (Auricularia auricula-judae), which is commercially cultivated in a plastic house in Jeju-si, South Korea. This study provides the damage symptoms and diag- nosable characteristics of adults and larvae of P. takeii.
Materials and Methods
The examined specimens were collected from wood ear mushrooms commercially cultivated in a plastic house at Hwabuk-myeon, Jeju-si, South Korea from April to August 2021. Some of the larvae were reared in the laboratory. Images were captured with a digital microscope camera (USB 3.0, DMC- 2900, Leica Biosystems, Buffalo Grove, IL, USA) attached to a Leica M125 stereo microscope (Leica Biosystems). The pictures were stacked using the Leica Application Suite software version 4.8 (Leica Biosystems).
Results
Taxonomic account
Family Tenebrionidae Latreille, 1802 (거저리과)
Subfamily Diaperinae Latreille, 1802 (르위스거저리아과)
Genus Platydema Laporte & Brullé, 1831
Platydema Laporte & Brullé, 1831, Ann. Sci. Nat. 23: 350. [Type species: Platydema dejeanii Laporte & Brullé, 1831].
Anisochara Gebien, 1925, Phil. J. Sci. 28: 101. [Type species: Anisochara gynadromorpha Gebien, 1925]
Histeropsis Chevrolat 1878, Pet. Nouv. Entomol. 2: 221. [Type species: Platydema americanum Laporte & Brullé, 1831].
Typhobia Pascoe 1869, Ann. Mag. Nat. Hist. (4)3: 279. [Type species: Typhobia fuliginea Pascoe, 1869]
Keys to the Korean Platydema species (Jung, 2017)
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Body extremely convex, metallically shining, with weak iridescence ················································· P. higonium
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Elytra with brownish yellow markings at the sub-basal part ····························································· P. subfascia
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Clypeal anterior margin with a small tubercle ················ ····································································· P. celatum
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Frons without horns or tubercles on the inner ocular area in both sexes ································································ 5
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Body shining; pronotum widely triangular ····················· ····································································· P. lynceum
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Body length approximately 7.0 mm; male middle and hind tibiae not curved at the middle part inwardly; ocular distance almost equal to the eye diameter ····················· ··································································· P. fumosum
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- Body length > 10.0 mm; male middle and hind tibia curved inward at the middle part (Ando, 1985); ocular distance closed, narrower than the eye diameter ··········· ································································· P. umbratum
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Frons with a pair of long, slender horns, reaching beyond the head in males; frons at the base of horns shallowly concave in both sexes ································ P. recticorne
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Elytra shallowly and weakly striated, with small punctures ······························································· P. takeii
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Pronotum strongly transverse and abruptly narrowing near apex ······················································ P. kurama
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Body length > 5.5 mm; elytral interstriae strongly convex and densely punctate ··························· P. marseuli
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Elytral interstriae strongly convex with sparse and minute punctures ················································· P. koreanum
Platydema takeii Nakane, 1956 제주진주거저리
Platydema takeii Nakane, 1956:165 [TL: Japan]; Jung, 2017: 49-50, Fig. 1, 3 [Korea-Jeju].
Diagnosis
Adult (modified from Jung, 2017): Body length approximately 5.5 mm in females and 5.2 mm in males. Body oval-oblong, strongly shining, and mostly black; antennae, mouthpart, horns (partly), and legs reddish brown. Head with tiny punctures. Antennae moniliform, 1st to 3rd antennomeres cylindrical, 4th to 11th antennomeres moniliform, and enlarged transversely. Pronotum strongly convex with small regular punctures. Scutellum triangular. Elytra strongly convex. All tibiae and tarsi relatively slender and long. Male (Fig. 1A-B): frons with a pair of moderately long horns, horns gradually thin apically, brownish black at basal 3/5, and reddish brown at apical 2/5. Female (Fig. 1C-D): frons with a pair of short and blunt horns, approximately twice shorter than those of males.
Larva (Fig. 2A-B): Last instar is cylindrical and strongly sclerotized on its surface, with well-developed anal tube in the ninth abdominal tergite.
Pupa (Fig. 2C): Typical tenebrionid pupal shape.
Material examined: 6♂♂, 10♀♀, 3 larvae, 2 pupa, Hwabuki-dong, Jeju-si, 8.Ⅳ.2021, 31.Ⅷ.2021 in the wood ear mushrooms commercially cultivated in a plastic house, K.J. Hong leg.
Distribution: Korea (Jeju-si), Japan, and Taiwan (Masumoto et al., 2013).
Food material: Auricularia polytricha (Mont.) Sacc. (Jung, 2017) and A. auricula-judae (Fr.) Quel. (Auriculariaceae).
Damage symptoms
Larvae and adults of P. takeii attack wood ear mushrooms; however, the immature stages of P. takeii c ause t he m ost damage. They mostly feed on the fruiting bodies of wood ear mushrooms. During feeding, larvae emit thread-like bundle residuals, inside which they may hide (Fig 3). Larvae are quite active; they crawl very quickly when exposed from their hiding place or in danger. Damage to the basal area of the mushroom may result in the dropping of fruiting bodies from the culture compost bag. In severe cases, a complete loss of the cultivated mushrooms may occur.
Discussion
A tenebrionid beetle that caused severe destruction of wood ear mushrooms cultivated in eco-friendly plastic greenhouses was identified as P. takeii Nakane. This pest is a fungivorous tenebrionid commonly found in Jeju-si as an endemic species.
To the best of our knowledge, this is the first report of a fungivorous tenebrionid causing serious economic damage to commercial mushrooms. As the number of eco-friendly farms cultivating mushrooms increases, damage reports are expected to continue in the future. Therefore, control measures are required.
KSAE
