Atheta (Dimetrota) yamamotoi Sawada, 1989

Lee, Seung-Gyu & Ahn, Kee-Jeong, 2022, Korean species of the Atheta Thomson subgenus Dimetrota Mulsant & Rey (Coleoptera: Staphylinidae: Aleocharinae) with a description of new species, Zootaxa 5138 (4), pp. 401-416 : 411-412

Atheta (Dimetrota) yamamotoi Sawada, 1989

( Figs. 1C , 7A–I )

Atheta (Dimetrota) yamamotoi Sawada, 1989: 292 ; Smetana, 2004: 376; Schülke & Smetana, 2015: 534.

Description. Length 2.7–3.5 mm. Body ( Fig. 1C ) dark brown to black; head almost black; elytra brown; basal segments of antennae and legs yellowish brown. Head. Subquadrate, approximately 1.0–1.1 times as wide as long, widest across eyes, slightly narrower than pronotum; eyes large and prominent, about 1.5 times as long as temples; gular sutures moderately separated, diverged basally; cervical carina complete. Antennae ( Fig. 7A ) long and slender; antennomeres 1–3 elongate, 1 longest, 2 slightly longer than 3, 4–5 slightly elongate, 6–10 quadrate to subquadrate, 11 longer than wide, slightly shorter than the preceding two combined. Mouthparts. Labrum transverse, slightly emarginate in anterior margin, with ε-sensillum and 9–10 macrosetae on each side of midline; epipharynx with α-sensillum long and setaceous, more than 3.0 times as long as ε-sensillum; β- and γ-sensilla short, blunt at apex. Mandibles asymmetrical, subtriangular, decurved and pointed apically, about 1.6 times as long as basal width; moderately very few small denticles present in molar region; right one with small internal tooth, internal margin slightly serrulate; prostheca developed, composed of three portions. Lacinia of maxilla moderately long; maxillary palpus elongate and pubescent; palpomere 1 smallest, 2 about 2.7–2.8 times as long as wide, 3 slightly longer than 2, about 2.7–2.9 times as long as wide, 4 digitiform, filamentous sensilla almost reaching to basal half. Prementum with two medial setae narrowly separated; two basal pores close together, 1.0–2.0 times of basal width; several medial pseudopores, lateral pseudopores, 1 setal pore and 2 real pores present on each side of midline; labial palpomere 1 largest, about 1.4–1.6 times as long as wide, γ-setula contiguous with b-seta, 2 shortest, about 1.2–1.4 times as long as wide, 3 more or less dilated apically and about as long as 1, about 3.0 times as long as wide. Mentum trapezoidal, anterior margin slightly emarginate; v-seta closer to u-seta than w-seta. Thorax. Pronotum approximately 1.3–1.4 times as wide as long, widest at middle. Metanotal scutum with 1 long seta and about 5–8 relatively short setae on each side of midline. Mesoventral process slightly pointed at apex, longer than isthmus and metaventral process combined; length ratio of mesoventral process, isthmus and metaventral process 12:5:3. Elytra slightly longer and wider than pronotum; elytron approximately 1.6–1.7 times as long as wide; hind wings fully developed, flabellum composed of about 7–10 long setose lobes. Legs. Length ratio of tarsomeres 29:34:37:90 (protarsus); 32:41:43:41:88 (mesotarsus); 49:54:51:51:111 (metatarsus). Abdomen. Surface glossy and densely pubescent, with transversely reticulate microsculpture; macrochaetal arrangement of tergites II–VI 02-13-13 (or 23)-13 (or 23)-13 (or 23); male tergite VIII ( Fig. 7B ) with 4 macrosetae on each side of midline, posterior margin with two blunt outer processes in postero-lateral margins and about 7–9 blunt inner processes, outer processes slightly longer than inner processes; male sternite VII with numerous granular punctures in posterior region; male sternite VIII ( Fig. 7C ) with about 10 macrosetae on each side of midline, posterior margin convex, with inconspicuous marginal setae; posterior margin of female tergite VIII ( Fig. 7D ) truncate, slightly emarginate in median region; female sternite VIII ( Fig. 7E ) with 7 macrosetae on each side of midline, posterior margin rounded, with conspicuous marginal setae, minute setae present in median region. Aedeagus. Median lobe ( Figs. 7F–G ) ovate, basal region of apical process constricted in ventral aspect. Apical lobe of paramerites ( Fig. 7H ) elongate, parallel-sided, with 4 setae; a-seta longest, the other setae subequal in length. Spermatheca. S-shaped; bursa elongate, with relatively large umbilicus ( Fig. 7I ).

Material examined. SOUTH KOREA: Chungbuk Prov.: 8 exx. (two on slide), Yeongdong-gun, Sangchonmyeon, Mulhan-ri , Mt. Minjujisan , N36˚03'35.22" E127˚52'31.26", 518 m, 13 v 2010, SG Lee, decaying persimmon . Chungnam Prov.: 3 exx. (one on slide), Daejeon-si, Mt. Gyeryongsan, Sutonggol , 21 iv 1998, KJ Ahn, HJ Kim, HJ Lim, KL Yu, bait trap . Jeonbuk Prov.: 2 exx., Jinan-gun, Mt. Unjangsan , 18 v 1995, YB Cho . Jeonnam Prov.: Suncheon-si, Seonamsa , 1 v 1988, JC Paik .

Distribution. Korea (South) and Japan.

Remarks. Atheta (Dimetrota) yamamotoi is very similar to A. (Atheta) transfuga , but can be distinguished by the male sternite VIII ( Fig. 7C ) with about 10 macrosetae on each side of midline; female sternite VIII ( Fig. 7E ) with 7 macrosetae on each side of midline. This species is recorded here for the first time in Korea.

Figures

FIGURE 1. Habitus.A: Atheta (Dimetrota) machonryongica (3.0 mm); B: A. (D.) ovata sp. nov. (3.0 mm); C: A. (D.) yamamotoi (3.2 mm).

FIGURE 7. Atheta (Dimetrota) yamamotoi. A: antenna; B: male abdominal tergite VIII (dorsal aspect); C: male abdominal sternite VIII (ventral aspect); D: female abdominal tergite VIII (dorsal aspect); E: female abdominal sternite VIII (ventral aspect); F: median lobe of aedeagus (lateral aspect); G: median lobe of aedeagus (ventral aspect); H: paramere (lateral aspect); I: spermatheca. Scales = 0.1 mm.