Eupiestus, Kraatz, 1859

Park, Joon-Yong & Ahn, Kee-Jeong, 2022, Description of a New Species of Eupiestus Kraatz (Coleoptera: Staphylinidae: Piestinae) in Korea, The Coleopterists Bulletin 76 (3), pp. 482-485 : 482-485

Genus EUPIeSTUS Kraatz, 1859

Type species: Eupiestus sculpticollis Kraatz , fixed by monotypy.

EUPIeSTUS roTUndIfronS Park and Ahn , new species zoobank.org/ urn:lsid:zoobank.org:act:9598D8C0-60B5-4C35-8FF1-3FD8356E1277 ( Figs. 1–13 )

Type Specimens. Holotype, ♂, labeled as follows: “ KOREA: Chungnam Prov., Daejeon-si, Dong-gu, Secheon-dong, Mt. Sikjangsan , 2019– 2020, WJ Jeong, JY Park, GN Jeon, YJ Kim, YJ Lim, YJ Shin, under bark; HOLOTYPE Eupiestus rotundifrons Park and Ahn 2022 ”. Deposited in CNUIC . Paratypes, 13 exx. ( CNUIC): 8♂ 5♀, same data as holotype; 1, “ KOREA: Gangwon Prov., Pyeongchang-gun, Jinbu-myeon, Mt. Odaesan , N37°45′58.3 E128°34′37.1″ 770m, 27 V 2010, KJ Ahn, SG Lee, under bark”; 2 exx., “ KOREA: Kangwon Prov. , Hoengsungun, Unduryeng, 9–10 IX 1998, K.-J. Ahn, ex under bark” .

Other Specimens Examined. 9 exx. ( CNUIC): 3♂ 5♀, same data as holotype; 1♂, “ KOREA: Chungnam Prov., Daejeon- si, Dong-gu, Sechondong , N36°19′34.76″ E127°29′02.05″ 118 m, 8 VII 2020, JY Park, YJ Kim, YJ Shin, under bark” .

Description. Body length 2.8–3.1 mm. Body flattened dorso-ventrally. Head black to dark brown; pronotum black to dark brown; elytra dark brown to brown; abdomen black to dark brown; antennomeres 1–11 reddish-brown; mandibles reddish-brown to brown with dark distal area, maxillary and labial palpi and legs reddish-brown to brown.

Head. Subtriangular with curved anterior margin, about 1.25–1.43 times as wide as long, about 0.83–0.92 times as wide as pronotum; surface glossy with coarse punctures; disc with one pair of relatively large and elevated antennal tubercles, a pair of deep and large depressions located near inner sides of antennal tubercles, a deep and large fovea located in medio-basal region; eye moderate in size, about 0.31–0.39 times as long as head; gular sutures converged at about apical one-third; antennae long, relative length ratio of each antennomere 24:13:12: 9:10:11:11:10:10:10:16; relative width ratio of each antennomere 12:10:10:10:11:12:13:12:13:13:12. Mouthparts. Labrum slightly transverse, anterior margin more or less rounded, lateral margin almost straight; mandible without tooth; maxillary palpus elongate, palpomere 4 fusiform, longer than 3; labial

(dashed line) of pronotum; 3) Dorsolateral ridge (dashed line) of elytra. Scale bars = 0.5 mm.

484 palpus elongate, palpomere 3 suboval, longer than glossy with larger and deeper punctures than head; 2; ligula not divided. Thorax. Pronotum moderately elytra 0.6–0.7 mm long, 0.7–0.8 mm wide, slightly narrowed anteriad and distinctly narrowed posteri- wider than long, with large and deep punctures, ad, about 1.20–1.38 times as wide as long, widest posterior margin slightly concave; each elytron with at middle; disc with one pair of long and prominent four longitudinal ridges excluding marginal sutures, keels in sublateral region, two pairs of short keels dorsolateral ridge slightly concave ( Fig. 3 ). in apical half and basal half of median region, su- Abdomen. Slightly narrowed posteriad, finely perior marginal line slightly constricted in middle punctate; surface glossy with coarse punctures. ( Fig. 2 ), large foveae located between keels and Male. Tergite VIII more or less rounded apically between keel and superior marginal line; surface ( Fig. 4 ); sternite VIII triangularly produced medio-apically ( Fig. 5 ); sternite IX slightly asymmetrical at basal part, rounded apically with several apical setae ( Fig. 6 ); tergite X more or less rounded apically with several apical setae ( Fig. 7 ); median lobe of aedeagus rounded at apex, with rounded basal capsule ( Fig. 8 ); median lobe curved dorsally and narrowed apically in lateral view ( Fig. 9 ); internal sac with one long curved sclerite in middle and two symmetrical spear-like sclerites dorsally on both sides ( Figs. 8–9 ); paramere bilobed, slender, rounded at each apex, with several apical setae, transparent hemispherical sclerites on inner sides of apical 1/7, transparent longitudinal sclerites on inner sides from apical 1/7 to 1/2 ( Fig. 10 ). Female. Tergite VIII similar to that of male ( Fig. 11 ); sternite VIII broadly prominent medio-apically ( Fig. 12 ); gonocoxites once-coiled with some minute setae ( Fig. 13 ); tergite X with deep and narrow emargination at basal part, more or less rounded apically with several apical setae ( Fig. 13 ).

Distribution. Korea (South).

Etymology. The name is derived from the Latin rotund and frons meaning “rounded front”, which refers to the rounded clypeus of the species.

Remarks. The new species is similar to E. sikkimi in the body form and structure (head subtriangular with curved anterior margin), body length (around 3.0 mm) and the slightly transverse antennomeres 6–10, characters that the other Palearctic species do not possess. The new species can be distinguished from E. sikkimi by the slightly constricted superior marginal lines of pronotum at middle ( Fig. 2 ), the slightly concave dorsolateral ridges of elytra ( Fig. 3 ), and the different form and structure of the aedeagus ( Figs. 8–10 ).

Formerly, the northernmost record of the genus Eupiestus was Tibet ( E. longipennis , E. sikkimi ), but now its distributional range is extended farther north (Korean peninsula) by the discovery of this new species.

Figures

Figs. 1–3. Eupiestus rotundifrons, new species. 1) Habitus, holotype, male, 2.8 mm; 2) Superior marginal line

Figs. 4–13. Eupiestus rotundifrons, new species. Male: 4) Tergite VIII, dorsal view; 5) Sternite VIII, ventral view; 6) Sternite IX, ventral view; 7) Laterotergal sclerites and tergite X, dorsal view; 8) Aedeagus, ventral view; 9) Aedeagus, lateral view; 10) Paramere, ventral view. Female: 11) Tergite VIII, dorsal view; 12) Sternite VIII, ventral view; 13) Abdominal segments IX (right) and X; dorsal view. Scale bar = 0.1 mm.