New record of the genus Typhlocolenis Hoshina, 2008 (Coleoptera, Leiodidae) from South Korea with a key to the species

Abstract This is the first record of the genus Typhlocolenis Hoshina, 2008 (Coleoptera, Leiodidae, Leiodinae, Pseudoliodini) in South Korea. Two new Korean species are described, under the names T. sillaensissp. nov. and T. jejudoensissp. nov. As a result of this study, the number of Typhlocolenis species is now five. A key to the species of the genus is provided.


Introduction
The genus Typhlocolenis belongs to the tribe Pseudoliodini Portevin, 1926 of the subfamily Leiodinae Fleming, 1812 of the family Leiodidae (Perreau 2015) and was established based on three Japanese species by Hoshina (2008). Since then, no species have been added to this genus; therefore, Typhlocolenis was considered to be endemic to Japan (Perreau 2015). Typhlocolenis is a blind and wingless genus that can be distinguished from the blind genus Zelodes Leschen, 2000 of Pseudoliodini by its metaventrite with a median carina. In contrast, Zelodes has no median carinae on its metaventrite (Leschen 2000;Hoshina 2008).
In South Korea, three species of two genera of Pseudoliodini, Dermatohomoeus terrenus (Hisamatsu, 1985), Pseudcolenis hilleri Reitter, 1885, and P. hoshinai Park & Ahn, 2007, have been recorded (Park and Ahn 2007; National Institute of Biological Resources 2019). Recently, we studied approximately 20 previously unidentified Korean specimens of Pseudoliodini in the collection of the National Institute of Biological Resources, Incheon. The specimens were collected from forest litter layers by sifting. After careful examination, we discovered that the specimens represented two new species of Typhlocolenis. In this paper, we record the genus for the first time in South Korea, describe these new species, and provide a key to the species of the genus.

Materials and methods
All specimens used in this study were deposited in the National Institute of Biological Resources (NIBR), Incheon, South Korea.
The methods were the same as those described in Hoshina (2012). Length and width of head, pronotum, and elytra are measured as follows: length of head is from anterior margin of clypeus to basal margin of head; width of head is between external margins of both eyes; length and width of pronotum and elytra are vertical and horizontal maximum.
Key to the species of the Typhlocolenis genus 1 Elytra not strigose, bearing large punctures (Fig. 5)  Median lobe of aedeagus relatively slender and bearing a relatively large nipple at apex in dorsal view (Fig. 11); distribution: Japan (Honshu) (Fig. 15) Median lobe of aedeagus feebly curved at lateral margins in dorsal view (Fig. 7); distribution: mainland of South Korea (Fig. 15)  Diagnosis. Body length approximately 1.3-1.4 mm. Dorsum almost concolorous, brown, or dark brown. Head and pronotum strongly microreticulate, sparsely and very minutely punctate. Elytra almost smooth, sparsely and very minutely punctate, and densely and transversely strigose. The median lobe of aedeagus relatively thick and feebly curved at lateral margins and bearing a relatively small nipple at apex in dorsal view.
Coloration. Dorsum of body shiny and almost concolorous, brown or dark brown; antennae light brown; mesoventrite brown or dark reddish brown with a black median carina; metaventrite brown or dark reddish brown with a dark brown median carina; abdominal ventrites brown or dark reddish brown; legs brown with light brown tarsi. Body 1.31-1.39 mm in length, approximately 1.8 times as long as wide (Fig. 1). Head approximately 1.6 times as wide as long, strongly microreticulate, sparsely and very minutely punctate; head length approximately 0.54 times pronotum length; head width approximately 0.48 times pronotum width; antennomeres 1-4 and 11 longer than wide; antennomere 5-7 almost as long as wide; other antennomeres wider than long; antennomere 11 approximately1.3 times as long as wide (Fig. 3).
Pronotum approximately 1.8 times as wide as long, strongly microreticulate, sparsely and very minutely punctate; pronotum length approximately 0.58 times elytron length; pronotum width almost same as elytron width.
Scutellum weakly microreticulate and almost impunctate or sparsely and very minutely punctate. Elytra almost as long as wide or slightly wider than long, widest at approximately basal 1/6, almost smooth, sparsely and very minutely punctate, and densely and transversely strigose (Fig. 6).
Legs show no sexual dimorphism on protarsi and normal shape for Typhlocolenis. Meso-and metaventrites strongly microreticulate, almost impunctate, and glabrous; abdominal ventrites strongly microreticulate, almost impunctate, and bearing sparse and very fine pubescences.
Female. Spermatheca generally crescent shaped (Fig. 13). Etymology. The specific name is derived from an ancient Korean kingdom, Silla, where is the type locality of the present new species.
Distribution. South Korea (Gangwon-Prov.) (Fig. 15). Differential diagnosis. The genus Typhlocolenis is here first recorded in South Korea and is the only blind genus in the Korean Pseudoliodini. Therefore, T. sillaensis sp. nov. can be easily separated from Dermatohomoeus Hlisnikovský, 1963 and Pseudcolenis Reitter, 1885 of the tribe by the lack of eyes. Moreover, T. sillaensis sp. nov. can be distinguished from Dermatohomoeus and Pseudcolenis by having a metaventrite with a distinct median carina. In contrast, Dermatohomoeus and Pseudcolenis have no median carinae on the metaventrites.
Typhlocolenis sillaensis sp. nov. is similar to T. fusca Hoshina, 2008 in appearance but can be distinguished by the relatively thick median lobe of aedeagus (Fig. 7) that has a relatively small nipple at the apex in dorsal view (Fig. 7). In contrast, T. fusca has a relatively slender median lobe that has a relatively large nipple at the apex in dorsal view (Fig. 11).
Natural history. The life history of Typhlocolenis sillaensis Hoshina & Park, sp. nov. is not known. Diagnosis. The present species very similar to Typhlocolenis sillaensis Hoshina & Park, sp. nov. Body length approximately 1.3-1.4 mm. Dorsum almost concolorous, brown to blackish brown. Head and pronotum strongly microreticulate, sparsely and very minutely punctate. Elytra almost smooth, sparsely and very minutely punctate, and densely and transversely strigose. The median lobe of aedeagus relatively thick, strongly expanded at about middle of lateral margins, and bearing a small nipple at apex in dorsal view.
Head approximately 1.5 times as wide as long, strongly microreticulate, sparsely and very minutely punctate; head length approximately 0.61 times pronotum length; head width approximately 0.48 times pronotum width; antennomeres 1-4 and 11 longer than wide; antennomere 5-7 almost as long as wide; other antennomeres wider than long; antennomere 11 approximately 1.3 times as long as wide (Fig. 4).
Pronotum approximately 1.8 times as wide as long, strongly microreticulate, sparsely and very minutely punctate; pronotum length approximately 0.52 times elytron length; pronotum width almost same as or slightly narrower than elytron width.
Scutellum weakly microreticulate and almost impunctate or sparsely and very minutely punctate.
Elytra almost as long as or slightly longer than wide, widest at approximately basal 1/6, almost smooth, sparsely and very minutely punctate, and densely and transversely strigose (Fig. 6).
Legs show no sexual dimorphism on protarsi and normal shape for Typhlocolenis. Meso-and metaventrites strongly microreticulate, almost impunctate, and glabrous; abdominal ventrites strongly microreticulate, almost impunctate, and bearing sparse and very fine pubescence.
Male. Aedeagus generally thick (Figs 9, 10); median lobe of aedeagus strongly expanded at about middle of lateral margins, and bearing a small nipple at apex in dorsal view (Fig. 9), slightly, and weakly curved in lateral view (Fig. 10); parameres almost symmetrical and bearing several apical setae (Figs 9, 10).
Female. Spermatheca generally C-shaped (Fig. 14). Etymology. The specific name is derived from the type locality, Jejudo Island. Distribution. South Korea (Jejudo Island) (Fig. 15). Differential diagnosis. Typhlocolenis jejudoensis sp. nov. is similar to T. sillaensis sp. nov. in appearance but can be distinguished by being strongly expanded at about middle of lateral margins in dorsal view (Fig. 9). In contrast, T. sillaensis sp. nov. has a very feebly curved median lobe in dorsal view (Fig. 7). Moreover, T. jejudoensis sp. nov. resembles T. furunoi Hoshina, 2008 in appearance but can be distinguished by median lobe of aedeagus with a small nipple at the apex in dorsal view (Fig. 9). In contrast, T. furunoi has a median lobe broadly rounded at the apex (Fig. 12).
Natural history. The life history of Typhlocolenis jejudoensis Hoshina & Park, sp. nov. is not known.

Notes of the distribution of Typhlocolenis
The genus Typhlocolenis is distributed only in East Asia (Fig. 15). Among all five species of Typhlocolenis, T. uenoi Hoshina, 2008 has been collected only in caves (Hoshina 2008). Others have generally been collected in litter layers of forests, although T. fusca specimens have sometimes been found in caves (Hoshina 2008). Currently, the two species of Typhlocolenis have not been concurrently collected at one location. It is possible that the two Korean species, T. sillaensis sp. nov. and T. jejudoensis sp. nov. are endemic to the mainland of South Korea and Jejudo Island, respectively (Fig. 15).