Thinobius koreanus Lee & Yoo, 2021

Lee, Jae-Seok, Yoo, In-Seong & Ahn, Kee-Jeong, 2021, Taxonomy of the coastal Thinobius Kiesenwetter (Coleoptera: Staphylinidae Oxytelinae) in Korea, Zootaxa 4985 (2), pp. 261-268 : 264-265

Thinobius koreanus Lee & Yoo sp. n.

( Figs. 1B , 4–5 )

Description. Length 1.60–1.80 mm. Body flattened, surface pubescent; light brown to dark brown, head and abdomen dark brown, pronotum, elytra and antenna brown, mouthparts and legs light brown. Head. Almost as long as wide and slightly narrower than pronotum; widest across eyes; clypeus trapezoidal; eye moderate in size and rounded in lateral aspect, with large eye facet and interfacetal setae; temple well developed, diameter of eye slightly longer than temple; gular suture fused and broadly divergent at posterior part; neck well developed, transversely reticulate sculptures distinct, seta absent ( Fig. 4B ); antenna slender, moderately elongate, and pubescent; antennomere 1 longest, 3 shortest, 1–11 elongate ( Fig. 4A ). Mouthparts. Labrum transverse, lateral margin rounded, anterior margin slightly emarginate; mandible triangular, apex bifid with subapical tooth, prostheca and molar tooth well developed; maxillary palpus with four palpomeres, palpomere 1 transverse and small, 2 slightly dilated to apex, 3 largest, 2–3 with many setae, 4 short and slender; apical margin of 3 more than 2.0 times as wide as basal margin of 4; labial palpus with three elongate palpi, palpomere 1 with one long, one short seta and two pores, 2 with one long seta and one pore, 3 with few short sensilla at apex; mentum quadrate with two pairs of long macrosetae and many setae. Thorax. Pronotum transverse, width 0.29–0.30 mm, widest near half of length, surface pubescent with seven pairs of macrosetae and many setae; prosternum with one pair of long setae and a few short setae, apex of prosternal process sharp and elevated ( Figs. 4C–D ); scutellum an inverted triangle, anterior margin of scutellum emarginate, posterior part reticulate with a few setae and inverted triangle impression, impression about 1.6 times as wide as long, elytron elongate and pubescent; posterior margin with membranous lobe; hind wing present; mesoventral process slightly extended and pointed at apex; metaventral carina absent; metaventrite distinctly reticulate with two pairs of long macrosetae and many setae ( Fig. 4E ); all tibiae with one long macroseta in middle. Abdomen. Posterior margin of tergite VII with fringe of setae; posterior margin of tergite VIII emarginate; posterior margin of sternite VIII convex. Secondary sexual characteristics. Male tergite IX with ventral structs, struts shorter than other part, female gonocoxites present; female with one ring structure ( Fig. 4F ). Genitalia. Aedeagus oval ( Fig. 5A ) with serrated pattern in lateral aspect ( Fig. 5B ); paramere long and slender; spermatheca as in Fig. 5C .

Type material. Holotype, 1 ♂, labeled as follows: ‘ KOREA: Gyeongbuk Prov., Pohang-si, Buk-gu, Cheongha-myeon, Cheongjin-ri , N36°10'38.73" E129°23'37.15" 17 m, 12 VII 2018, IS Yoo, JS Lee, JG Jung, in coarse sand/gravels on seashore, flotation’ ‘ Holotype, Thinobius koreanus Lee and Yoo, Desig. Jae-Seok Lee and In-Seong Yoo, 2021 ’ ‘ Deposited in the Chungnam National University Insect Collection, Korea’ . Paratypes, 7 exx., same data as holotype, 5 exx., same data as holotype except for ‘ N36°10ʹ37.8 ʺE129°23ʹ38.0ʺ 9m, 27 VIII 2010, KJ Ahn, TK Kim, YH Kim, IS Yoo, JH Song, SG Lee, JH Jeon, under stones on seashore .’

Distribution. Korea.

Remarks. This species is similar to T. marinus , but can be distinguished by the shape of antennomeres. Antennomeres 1–11 are elongate in Thinobius koreanus sp. n. ( Fig. 4A ), but 4–8 transverse in T. marinus . The new species is also similar to T. frizzelli from Canada and USA but can be distinguished by the shape of antennomeres. Antennomeres 4–10 are quadrate and 4–6 are almost same length in the new species ( Fig. 4A ), but 4–10 rounded form and 5 larger than 4 or 6 in T. frizzelli ( Kincaid, 1961) . All specimens were collected in the southern part of the Korean peninsula.

Figures

FIGURE 1. Habitus of Korean coastal Thinobius. A. Thinobius jejuensis sp. n., 1.04 mm; C. Thinobius koreanus sp. n., 1.60 mm; B. Thinobius kuroshio, 1.06 mm.

FIGURE 4. Thinobius koreanus sp. n. A: antenna; B: head, dorsal aspect; C: pronotum, dorsal aspect; D: prosternum, ventral aspect; E: meso- and metaventrite, ventral aspect; F: ring structure with female genital appendage. Scales = 0.1 mm. Circles in B and E show magnification of sculptures.

FIGURE 5. Thinobius koreanus sp. n. A: aedeagus, ventral aspect; B: aedeagus, lateral aspect; C: spermatheca. Scales = 0.1 mm.