Parapyxidicerus Sawada, 1964

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 : 415-419

Genus Parapyxidicerus Sawada, 1964

Parapyxidicerus Sawada 1964: 11 ; Coulon 1989: 74; Kang et al. 2020: 355. Type species: Parapyxidicerus carinatus Sawada, 1964 .

Parapyxidicerus carinatus Sawada, 1964 ( Figs. 2A, E , 3A, E , 4 , 5 , 12A, E , 13A )

Parapyxidicerus carinatus Sawada 1964: 11 ; Coulon 1989: 76; Kang et al. 2020: 355.

Material Examined (n = 26, 14 ♂♂, 12♀♀). Korea: 2♂♂ (1♂ dried, genitalia dissected; 1♂ dried; CBNUIC) , Gyeongbuk Prov. Ulleung-gun, Buk-myeon, Na-ri , 26.VIII.2020, 37°30′51.5′′N 130°52′07.3′′E, 432 m, sifting soil and leaf litter, M.-H. Song, J.-W. Kim, Y.-J. Choi ; 1♂ (dried, genitalia dissected; CBNUIC) , Gyeongsan-si, Yongseongmyeon, Yukdong-ro , 02.VII.2021, 35°47′40.1′′N 128°56′19.9′′E, 345 m, sifting soil and leaf litter, M.-H. Song, U.-J. Byeon, J.-I. Shin ; 1♂ (dried, genitalia dissected; CBNUIC) , Yecheon-gun, Youngmunmyeon, Nosa-ri , 19.VII.2019, 36°40′48.0′′N 128°25′09.0′′E, 134 m, sifting soil and leaf litter, U.-J.Byeon ; 1♀ (dried; CBNUIC) , Uljin-gun, Onjeongmyeon, Onjeong-ri , Mt. Baegam , 23.IV.2021, 36°42′16.0′′N 129°18′57.0′′E, 256 m, sifting soil and leaf litter, Y.-J. Choi, T.- Y. Jang, M.-H. Song ; 1♀ (dried; CBNUIC) , Changnyeong-gun, Seongsanmyeon, Seongsan-ri , 639, 24.IV.2021, 35°36′15.1′′N 128°31′20.6′′E, 141 m, sifting soil and leaf litter, U.-J. Byeon, J.-W. Kim ; 1♂, 1♀ (slide mounted; CBNUIC) , Jeonbuk Prov. Gunsan-si, Seongsanmyeon, Hwandong-gil , 169, 03.VIII.2021, 36°00′29.4′′N 126°46′57.5′′E, 137 m, sifting soil and leaf litter, J.-W. Kang, J.-W. Kim ; 2♀♀ (dried; CBNUIC) , same locality, 36°00′33.6′′N 126°47′03.6′′E, 158 m, sifting soil and leaf litter, J.-W. Kang, J.-W. Kim ; 1♀ (dried; CBNUIC) , Iksan-si, Nangsan-myeon, Jangam-gil , Simgok temple 113, 36°02′19.8′′N 127°02′19.4′′E, 156 m, sifting soil and leaf litter, U.-J. Byeon, J.-W. Seo, M.-H. Song ; 1♀ (dried; CBNUIC) , Jeonnam Prov. Gurye-gun, Masan-myeon, Yeongilam-gil , 13. V.2020, sifting ant colony, M.-S. Dong ; 1♂ (dried; CBNUIC) , Gangwon Prov. Gangneung-si, Gangdong-myeon, Dangyeong-ro , 841, 37°40′21.0′′N 128°55′00.2′′E, 134 m, sifting soil and leaf litter near stream, U.-J. Byeon ; 1♂ (dried, genitalia dissected; CBNUIC) , Jeongseon-gun, Bukpyeongmyeon, Odaecheon-ro , 23.IV.2020, 37°26′52.3′′N 128°38′15.5′′E, 364 m, sifting soil and leaf litter, U.-J. Byeon ; 1♂ (dried; CBNUIC) , Yeoryangmyeon, Gujeol-ri , 19.VIII.2020, 37°32′25.7′′N 128°43′41.1′′E, 484 m, sifting soil and leaf litter, U.-J. Byeon, M.-H. Song ; 1♂ (dried; CBNUIC) , Yangyang-gun, Seo-myeon, Oseak-ri , Mt 13-2, 06. V.2019, 38°04′40.0′′N 128°29′51.0′′E, 276 m, sifting leaf litter near dried stream, J.-S. Park ; 1♂ (dried, genitalia dissected; CBNUIC) , Chungbuk Prov. Jecheon-si, Hansu-myeon, Mireuksonggye-ro , 1560-35, 09. VI.2021, 36°52′52.0′′N 128°05′10.0′′E, 276 m, sifting soil and leaf litter, J.-I. Shin, M.-H. Song ; 1♂ (dried; CBNUIC) , Boeun-gun, Songnisanmyeon, Beopjusa-ro , 16. V.2022, 36°32′55.3′′N 127°51′29.3′′E, 551 m, sifting soil and leaf litter, M.-H. Song, J.-I. Shin, J.-W. Kang ; 1♂, 1♀ (slide mounted; CBNUIC) , Seoul. Gangbuk-gu, Uidoung , 23.VIII.2019, 37°39′33.5′′N 126°59′22.8′′E, 148 m, sifting soil and leaf litter and deadwood debris, Y.-J. Choi, T.- Y. Jang ; 1♂ (dried; CBNUIC) , Jongno-gu, Pyeongchang-dong , 24.VIII.2019, 37°37′14.4′′N 126°57′52.3′′E, 207 m, sifting leaf litter and mushroom, Y.-J. Choi, T.- Y. Jang ; 1♀ (dried; CBNUIC) , Eunpyeong-gu, Jingwan-dong , 09.VII.2019, 37°38′37.0′′N 126°57′04.0′′E, 180 m, sifting soil and leaf litter, Y.-J. Choi, J.-W. Kang ; 1♂ (dried; CBNUIC) , Busan. Yeongdo-gu, Dongsamdong, Jeonamg-ri , 24, 13. V.2020, sifting ant colony, M.-S. Dong ; 2♀♀ (dried; CBNUIC) , Jeju Island. Jeju-si, Jocheon-eup, Gyorae-ri , Mt. 98, Gotjawal NRC, 19.VII.2021, J.-S. Oh, J.-W. Son, W.-W. Kim, S.-W. Yun ; 1♂ (dried, genitalia dissected; CBNUIC) , 1100-ro, 12. VI.2022, 33°25′03.5′′N 126°29′24.2′′E, 581 m, sifting soil and leaf litter, J.-I. Shin, J.-W. Kang.

Diagnosis. Adult males of this species can be distinguished from P. koreanus by the following characters: body size larger ( Figs. 2A, E , 3A, E ); aedeagus wide, with incurved apical process, incurved median process of upper angle ( Figs. 12A, E ).

Redescription. Body length 1.48–1.64 mm (17 specimens measured), color reddish brown, body flattened ( Figs. 2A, E , 3A, E ); pronotum slightly wider than head, head and pronotum densely punctate ( Figs. 4A, B , 5A, B ); elytra wider and longer than pronotum ( Figs. 4C , 5C ); abdomen longer than elytra, shallowly punctate ( Figs. 4E, F , 5E, F ); hind wings fully developed. Head. Head with frontal rostrum one-third head width, rostrum as long as vertex, rostrum with distinct dorsal tentorial pits at base, antennal tubercles absent, eyes convex, temples slightly angular, vertex slightly expanded, single ventral tentorial pit present, genae slightly expanded ( Figs. 4A , 5A ); antenna attached beneath lateral margin of rostrum, composed of eleven antennomeres, antennomere I larger than II–IX, II larger than III–IX, III–VII similar in size, IX larger than III–VIII, X–XI clubbed, XI larger than X ( Figs. 4G , 5G ). Mouthparts. Maxillary palpi with first palpomere extremely reduced, second palpomere subrectangular, third palpomere small, fourth palpomere largest, semispherical, divided by deep furrow at middle ( Figs. 4J , 5J ); mandibles symmetrical, with three subapical teeth ( Figs. 4I , 5I ); labrum transverse and widest at anterior margin, anterior margin straight, with more than 20 setae ( Figs. 4H , 5H ). Thorax. Pronotum with distinct median antebasal impression, lateral antebasal foveae present; prosternum with lateral procoxal foveae ( Figs. 4B , 5B ); mesoventrite with median mesoventral foveae, lateral mesoventral foveae, and promesocoxal foveae ( Figs. 4D , 5D ); metaventrite with median metaventral foveae and lateral mesocoxal foveae ( Figs. 4D , 5D ); each elytron with three basal elytral foveae, with distinct carina on lateral margin more than half of elytron length ( Figs. 4C , 5C ). Abdomen. Abdominal tergites IV–VI with basolateral foveae and discal carinae, VII with shallow impression at basolateral margins, VIII with transverse carina across strong mediolateral impressions ( Figs. 4E , 5E ); abdominal sternite IV with mediobasal foveae, IV–VII with basolateral foveae ( Figs. 4F , 5F ).

Aedeagus. Aedeagus asymmetrical, wide, with incurved apical process, left median process, right median process incurved, upper angle bearing sharp apical process ( Figs. 12A, E ). Female. Head slightly narrower than male; abdominal sternite IX absent ( Fig. 5F ).

Distribution. South Korea ( Fig. 13A ), Japan.

Habitat. Specimens of P. carinatus were collected by sifting leaf litter and soil in the forest.

Parapyxidicerus koreanus Byeon and Park , new species zoobank.org/ urn:lsid:zoobank.org:act:62D1EDEA-24E3-4FAE-AC11-E0B4B3016DA7 ( Figs. 2B, F , 3B, F , 6 , 7 , 12B, F , 13B )

Type Material (n = 5, 3♂♂, 2♀♀). Holotype. 1♂ ( NIBR), “ Korea: Jeju Island. Seoseong-ro, Namwon-eup, Seogwipo-si , 27.IX.2021, 33°20′47.1′′N 126°40′36.4′′E, 322 m, sifting leaf & soil litter, J.-W. Kang, U.-J. Byeon ” . Paratypes. 1♂, 2♀♀ (1♂, 1♀ slide mounted; 1♀ dried; CBNUIC), same data as holotype ; 1♂ (dried, genitalia dissected; CBNUIC), Ulsan-si. Ulju-gun, Sangbuk-myeon, Alpeuseuoncheon 1-gil, 123, Mt. Sinbul , 28. VI.2021, 35º33′14.9′′N 129º03′56.9′′E, 324 m, sifting leaf and soil litter, T. - Y. Jang .

Diagnosis. Adult males of this species can be distinguished from P. carinatus by the following characters: body size small ( Figs. 2B, F , 3B, F ), aedeagus with sharp right apical process, and left twisted sclerotized membranous process ( Figs. 12B, F ).

Description. Body length 1.36–1.47 mm (3 specimens measured), color reddish brown, body flattened ( Figs. 2B, F , 3B, F ); pronotum slightly wider than head, head and pronotum densely punctate ( Figs. 6A, B , 7A, B ); elytra wider and longer than pronotum ( Figs. 6C , 7C ); abdomen longer than elytra, with shallow punctures ( Figs. 6E, F , 7E, F ); hind wings fully developed. Head. Head with frontal rostrum one-third head width, rostrum as long as vertex, with distinct dorsal tentorial pits, antennal tubercles absent, eyes convex, temples slightly angular, vertex slightly expanded, single ventral tentorial pit present, genae slightly expanded ( Figs. 6A , 7A ); antenna attached beneath lateral margin of rostrum, composed of eleven antennomeres, antennomere I larger than II–IX, II larger than III–IX, III–VII similar in size, IX larger than III–VIII, X–XI clubbed, XI larger than X ( Figs. 6G , 7G ). Mouthparts. Maxillary palpi with first palpomere minute, second palpomere subrectangular, third palpomere small, fourth palpomere largest, semispherical, divided by deep furrow at middle ( Figs. 6J , 7J ); mandibles symmetrical, with three subapical teeth ( Figs. 6I , 7I ); labrum transverse and widest at anterior margin, anterior margin straight, with more than 16 setae ( Figs. 6H , 7H ). Thorax. Pronotum with distinct median antebasal impression, with lateral antebasal foveae and median longitudinal sulcus; prosternum with lateral procoxal foveae ( Figs. 6B , 7B ); mesoventrite with median mesoventral foveae, lateral mesoventral foveae, and promesocoxal foveae ( Figs. 6D , 7D ); metaventrite with median metaventral foveae, with lateral mesocoxal foveae ( Figs. 6D , 7D ); each elytron with three basal elytral foveae, distinct carina on lateral margin more than half of elytron length ( Figs. 6C , 7C ). Abdomen. Abdominal tergites IV–VI with basolateral foveae and discal carinae, VII with shallow impression at basolateral margins, VIII with transverse carina across strong mediolateral impressions ( Figs. 6E , 7E ); sternite IV with mediobasal foveae, V–VII with basolateral foveae ( Figs. 6F , 7F ). Aedeagus. Aedeagus asymmetrical, narrower posteriorly, narrowest at the base, with sharp right apical process and left twisted sclerotized membranous process ( Figs. 12B, F ). Female. Eyes smaller, not convex ( Fig. 7A ); abdominal sternite IX absent ( Fig. 7F ).

Distribution. South Korea ( Fig. 13B ).

Etymology. This species is named after the country of the Republic of Korea.

Habitat. Specimens of P. koreanus 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. 4. Adult male Parapyxidicerus carinatus. 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. 5. Adult female Parapyxidicerus carinatus. 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.

Fig. 6. Adult male Parapyxidicerus koreanus, 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. 7. Adult female Parapyxidicerus koreanus, 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.