Euplectomorphus Motschulsky, 1863

Byeon, Ui-Joung & Park, Jong-Seok, 2023, Review of the Korean Species of the Tribe Bythinoplectini Schaufuss, 1890 (Coleoptera: Staphylinidae: Pselaphinae: Euplectitae), The Coleopterists Bulletin 77 (3), pp. 413-427 : 421-426

Genus Euplectomorphus Motschulsky, 1863

Euplectomorphus Motschulsky 1863: 424 ; Gemminger and Harold 1868: 698; Schaufuss 1888: 56; Raffray 1890: 265; Raffray 1904: 507; Raffray 1908: 21, 24; Raffray 1911: 9; Jeannel 1961: 427. Type species: Euplectomorphus pygmaeus Motschulsky 1863: 424 .

= Zethinellus Jeannel 1950: 31 (type species: Zethopsus nitidulus Reitter, 1884 ); Jeannel 1952: 53.

Euplectomorphus pygmaesimilis Byeon and Park , new species zoobank.org/ urn:lsid:zoobank.org:act:D57D29C4-56E9-4DA4-B96F-414B34E610E5 ( Figs. 2D, H , 3D, H , 10 , 11 , 12D, H , 13D )

Type Material (n = 90, 46♂♂, 44♀♀).

Holotype. 1♂ ( NIBR), “ Korea: Gyeongbuk Prov. Sanggeumgok-ri, Yongmun-myeon, Yecheon-gun , 14.IV.2019 36°41′51.0′′N 128°24′18.0′′E, 203m, Sifting, Leaf litter & Soil, U.-J. Byeon ” . Paratypes. 3♂♂, 4♀♀ (1♂, 1♀ slide mounted; 2♂♂, 3♀♀ dried; CBNUIC), same data as holotype ; 4♂♂, 3♀♀ (dried; CBNUIC), same locality , 20.IX. 2021, 36°41′52.4′′N 128°24′18.9′′E, 185 m, sifting soil and leaf litter, U.-J. Byeon; 4♂♂, 2♀♀ (dried; CBNUIC), same locality , 19.VII.2019, 36°41′52.0′′N 128°24′18.0′′E, 195 m, sifting soil and leaf litter, U.-J. Byeon; 1♂, 1♀ (dried; CBNUIC), same locality , 11.X.2019, 36°41′51.9′′N 128°24′18.8′′E, 176 m, sifting soil and leaf litter, U.-J. Byeon, S.-H. Choi; 2♀♀ (dried; CBNUIC), same locality , 04. V.2019, 36°41′51.0′′N 128°24′ 18.0′′E, 210 m, sifting soil and leaf litter, U.-J. Byeon; 1♂ (slide mounted; CBNUIC), same locality , 20.IX.2021, 36°41′52.4′′N 128°24′18.9′′E, 185 m, sifting soil and leaf litter, U.-J. Byeon; 1♀ (slide mounted; CBNUIC), same locality , 01. VI.2019, 36°41′52.0′′N 128°24′18.0′′E, 208 m, sifting soil and leaf litter, U.-J. Byeon; 1♂, 1♀ (dried; CBNUIC), Chungbuk Prov. Goesan-gun, Cheongjeonmyeon, Songmyeon-ri , 19.IX.2019, 36°39′48.2′′N 127°50′09.0′′E, 254 m, sifting leaf litter and deadwood debris, Y.-J. Choi, S.-H. Choi ; 1♂, 1♀ (dried; CBNUIC), Jecheon-si, Hansu-myeon, Songgye-ri , 10.IX.2020, 36°53′00.3′′N 128°05′32.0′′E, 393 m, sifting soil and leaf litter, Y.-J. Choi, U.-J. Byeon ; 1♀ (dried; CBNUIC), same locality , 23. V.2019, 36°52′52.8′′N 128°05′11.6′′E, 274 m, sifting soil and leaf litter, Y.-J. Choi; 1♀ (dried; CBNUIC), same locality , 28. V.2019,36°52′52.0′′N 128°05′10.0′′E, 262 m, sifting soil and leaf litter, M.-H. Song, U.-J. Byeon ; 1♂ (dried; CBNUIC), same locality , 28.X.2020. 36°52′52.0′′N 128°05′05.0′′E, 275 m, sifting soil and leaf litter, M.-H. Song, U.-J. Byeon; 1♀ (dried; CBNUIC), same locality , 28. V.2019, 36°52′52.0′′N 128°05′05.0′′E, 275 m, sifting soil and leaf litter, M.-H. Song, U.-J. Byeon; 2♂♂, 1♀ (dried; CBNUIC), same locality , 09. VI. 2021, 292 m, 36°52′53.3′′N 128°05′13.8′′E, 292 m, sifting soil and leaf litter and root, M.-H. Song, J.-I. Shin; 1♀ (dried; CBNUIC), same locality , 25. V.2021, 36°52′52.7′′N 128°05′06.4′′E, 252 m, sifting soil and leaf litter, J.-W. Kang, Y.-J. Choi, M.-H. Song; 3♂♂, 7♀♀ (1♂, slide mounted; 2♂♂, 7♀♀ dried; CBNUIC), same locality , 25. V.2021, 36°52′54.5′′N 128°05′16.4′′E, 313 m, sifting soil and leaf litter, J.-W. Kang, Y.-J. Choi, M.-H. Song; 6♂♂, 5♀♀ (dried; CBNUIC), same locality , 10.IX.2020, 36°53′00.3′′N 128°05′32.0′′E, 393 m, sifting soil and leaf litter, Y.-J. Choi, U.-J. Byeon; 11♂♂, 3♀♀ (dried; CBNUIC), same locality , 10.IX.2020, 36°53′00.3′′N 128°05′32.0′′E, 393 m, sifting soil and leaf litter, Y.-J. Choi, M.-H. Song; 4♂♂, 4♀♀ (dried; CBNUIC), Gangwon Prov. Hoengseong-gun, Cheongil-myeon, Yudong-ri , 16.II.2022, 37°34′39.0′′N 128°08′18.0′′E, 200 m, sifting soil and leaf litter, M.-H. Song, U.-J. Byeon ; 1♂, 3♀♀ (dried; CBNUIC), same locality , J.-W. Kang, J.-W. Seo, Y.-J. Choi; 1♂, 1♀ (slide mounted; CBNUIC), Hoengseong-gun, Anheung-myeon, Seodong-ro Sangan 2-gil, 25.IV.2022, 37°24′19.1′′N 128°11′11.4′′E, 581 m, sifting soil and leaf litter, J.-I. Shin, U.-J. Byeon, M.-H. Song ; 1♂, 1♀ (slide mounted; CBNUIC), Hoengseong-gun, Anheung-myeon, Seodong-ro , 21.IV.2022, 37°24′39.9′′N 128°10′14.2′′E, 608 m, sifting soil and leaf litter, J.-I. Shin, J.-W. Kang, J.-W. Seo, S.-H. Choi .

Diagnosis. Adult males of this species can be distinguished from E. pygmaeus by the aedeagal form. The apex of the median lobe of E. pygmaeus is thick and curved laterally, and the lateral spine is thin and slightly curved (see Jeannel 1961: 427, fig. 5), while apex of the median lobe of E. pygmaesimilis is relatively thin and less curved, and the lateral spine thick and strongly curved ( Figs. 12D, H ).

Description. Body length 0.91–1.02 mm (32 specimens measured), color reddish-brown, body flattened ( Figs. 2C, G , 3C, G ); head slightly wider than pronotum, head and pronotum densely punctate ( Figs. 10A, B , 11A, B ); elytra wider and longer than pronotum ( Figs. 10C , 11C ); abdomen longer than elytra, with shallow punctures ( Figs. 10E, F , 11E, F ); hind wings fully developed. Head. Head with frontal rostrum one-third head width, rostral length similar to that of vertex, rostrum with distinct dorsal tentorial pits at base, antennal tubercles absent, eyes convex, temples oblique, vertex slightly expanded medially, single ventral tentorial pit present, genae slightly expanded ( Figs. 10A , 11A ); antenna attached beneath lateral margin of rostrum, with eight antennomeres, antennomere I larger than II–VII, II larger than III–VII, III–VII similar in size, VIII largest, distinctly clubbed ( Figs. 10G , 11G ). Mouthparts. Maxillary palpi with first palpomere extremely reduced, second palpomere ovoid and angled at base, third palpomere shorter than second and angulate in apical third, fourth palpomere transverse, attached at middle of third palpomere, with small cap on basal end, rounded at apical end ( Figs. 10J , 11J ); mandibles asymmetrical, left mandible with two subapical teeth, right mandible with three subapical teeth ( Figs. 10I , 11I ); labrum transverse, widest at anterior margin, anterior margin straight, with more than 14 setae ( Figs. 10H , 11H ). Thorax. Pronotum with distinct median antebasal impression, with median longitudinal carina and distinct lateral antebasal foveae; prosternum with lateral procoxal foveae; mesoventrite with lateral mesoventral foveae and promesocoxal foveae ( Figs. 10D , 11D ); metaventrite with median metaventral fovea, with lateral mesocoxal foveae ( Figs. 10D , 11D ); each elytron with two basal elytral foveae, with distinct complete carina on lateral margin ( Figs. 10C , 11C ).

Abdomen. Abdominal tergite VII longest, IV–VII with basolateral foveae, VIII with transverse carina at middle ( Figs. 10E , 11E ); abdominal sternites IV– VII with basolateral foveae ( Figs. 10F , 11F ).

Aedeagus. Aedeagus asymmetrical, parameres absent, apex of median lobe blunt, lateral process wrapping around median lobe ( Figs. 12D, H ).

Female. Body size similar to male; abdominal sternite IX absent ( Fig. 11F ).

Distribution. South Korea ( Fig. 13D ).

Etymology. This species is named after the similar habitus and close aedeagal form of the type species of the genus, E. pygmaeus .

Habitat. Specimens of E. pygmaesimilis were collected by sifting leaf litter and soil in the forest.

Figures

Fig. 2. Adult male habitus. (A–D) Dorsal view, (E–H) Ventral view. A, E) Parapyxidicerus carinatus, B, F) P. koreanus, new species, C, G) Zethopsus omibongensis, new species, D, H) Euplectomorphus pygmaesimilis, new species.

Fig. 3. Adult female habitus. (A–D) Dorsal view, (E–H) Ventral view. A, E) Parapyxidicerus carinatus, B, F) P. koreanus, new species, C, G) Zethopsus omibongensis, new species, D, H) Euplectomorphus pygmaesimilis, new species.

Fig. 10. Adult male Euplectomorphus pygmaesimilis, new species. A) Head, B) Prosternum, C) Elytra, D) Meso- and metaventrites, E) Abdominal tergites, F) Abdominal sternites, G) Antennae, H) Labrum, I) Mandibles, J) Maxillae.

Fig. 11. Adult female Euplectomorphus pygmaesimilis, new species. A) Head, B) Prosternum, C) Elytra, D) Meso- and metaventrites, E) Abdominal tergites, F) Abdominal sternites, G) Antennae, H) Labrum, I) Mandibles, J) Maxillae.

Fig. 12. Aedeagus. A, E) Parapyxidicerus carinatus, B, F) P. koreanus, new species, C, G) Zethopsus omibongensis, new species, D, H) Euplectomorphus pygmaesimilis, new species.

Fig. 13. Collection localities.A) Parapyxidicerus carinatus, B) P. koreanus, new species, C) Zethopsus omibongensis, new species, D) Euplectomorphus pygmaesimilis, new species.