Bryaxis grandinodus Choi, Park, Lee & Park, 2023

Choi, Yeon-Jae, Park, Sun-Jae, Lee, Seung-Gyu & Park, Jong-Seok, 2023, Five new species of Bryaxis Kugelann (Coleoptera, Staphylinidae, Pselaphinae) from Korea and a nomenclatural note on Bryaxis mahunkai Loebl, ZooKeys 1182, pp. 165-181 : 165

Bryaxis grandinodus Choi, Park, Lee & Park sp. nov.

Figs 1 , 2A, C

Type materials

(N = 11, 6 ♂♂, 5 ♀♀). Holotype male. "Korea: Jeonnam Prov. Dangsan-ri, Gyegok-myeon, Haenam-gun, 18 May 2019, 34°40'53.0"N, 126°38'56.3"E, 211 m, sifting leaf litter & deadwood debris, J.-S. Park, M.-H. Song" (NIBR). Paratypes. 2♂♂, 2♀♀ (CBNUIC, 1♂, 1♀ slide mounted, 1♂, 1♀ dried). "Korea: Jeonbuk Prov. Sinsi island. Sinsido-gil, Okdo-myeon, Gunsan-si, 4 Jul 2022, 35°49'12.2"N, 126°27'35.1"E, 36 m, sifting leaf & soil litter, M.-H. Song, U.-J. Byeon, J.-W. Kang, T.-Y. Jang". 2♂♂ (CBNUIC, dried) "Korea: Jeonbuk Prov. Seonyu island. Seonyubuk-gil, Okdo-myeon, Gunsan-si, 16 Jun 2021, 35°48'36.5"N, 126°24'57.4"E, 25 m, sifting leaf, soil litter & fungi, J.-W. Kang, J.-I. Shin". 1♂, 3♀♀ (CBNUIC, DNA grade). "Korea: Jeonbuk Prov. Seonyu island. 5-1, Seonyunam-gil, Okdo-myeon, Gunsan-si, 4 Jul 2022, 35°48'24.7"N, 126°24'40.3"E, 9 m, sifting leaf & soil litter, M.-H. Song, U.-J. Byeon, J.-W. Kang, T.-Y. Jang".

Diagnosis.

Antennal scapes robust, with bowl-like glandular nodule on inner margin (Figs 1E, F , 2A , arrows), 2.45 times as long as pedicels; endophallus of male genitalia with three bifid struts, joined at base (Fig. 1I ).

Description.

Body reddish brown, antennae, maxillary palpi, and tarsi slightly lighter, length 1.2-1.32 mm, maximum width 0.51-0.58 mm (Fig. 1A-D ). Setae on body yellowish, long. Head 0.92 times as long as wide (Fig. 1E ). Frons with U-shaped impression between antennal tubercles; frontal foveae absent; frontal rostrum distinct anteriorly. Vertex slightly convex; longitudinal carina weak; vertexal foveae large. Eyes as long as tempora, with 23-26 facets. Maxillary palpi moderately developed; palpomeres II-III with tubercles; palpomere IV 0.23 mm long and about 3.15 times as long as wide, subcylindrical pseudosegment at apex. Antennae about 0.54 mm long; pedicels subglobose with long setae, 0.89 times as long as wide; antennomere III 1.12 times as long as wide; IV-VIII subequal in length; IX-X transverse, IX 0.64 times as long as wide and X 0.63 times as long as wide; XI largest, pointed at apex, 1.67 times as long as wide (Fig. 1F ). Pronotum 0.84 times as long as wide and widest at basal 2/3, lateral antebasal foveae connected by antebasal sulcus. Elytra slightly convex, 0.89 times as long as wide and widest at basal 1/4, each elytron with two basal foveae and subhumeral fovea. Legs slender; protibiae without spine (Figs 1G , 2C ); metatibiae with spine at apex (Fig. 1H , arrow). Aedeagus large, 0.37 mm long and 1.69 times as long as wide; penis bulbous and dorsal diaphragm ovoid; parameres short and symmetrical, apices almost encountered, one robust seta and three fine setae on each apex; endophallus divided into three large struts, left dorsal strut branched at basal 1/3 and bifid at apex, right dorsal strut weakly branched basally and bifid dorso-ventrally at apex, ventral strut robust and bifid at apex (Fig. 1I ).

Sexual dimorphism. Female eyes shorter than tempora, composed of 11 facets; antennal scapes subcylindrical, without modification; metatibial spines absent.

Remarks.

Adults of this species are very similar to Bryaxis koltzei (Reitter, 1887) in the general body characters, but can be distinguished by the shape of the antennal scapes and its glandular nodule (Fig. 2A , arrow) and the spineless protibiae in the male (Fig. 2C ).

Comments.

The localities of B. grandinodus sp. nov. probably overlap with those of B. koltzei (Reitter) given that the latter are distributed across the entire country (Fig. 11 ).

Etymology.

The specific epithet is a combination of the Latin words grandis ( “large”, masculine) and nodus ( “knob”, masculine) and refers to the shape of the glandular nodules on the male antennal scapes.

Habitat.

The holotype was collected by sifting leaf litter in mixed forest. Paratypes were collected by sifting leaf litter and soil.

Distribution.

Korea (Haenam-gun, Jeollanam-do; Gunsan-si, Jeollabuk-do).

Figures

Figure 1. Bryaxis grandinodus Choi, Park, Lee & Park, sp. nov., male (A, B, E-I), female (C, D). A, C dorsal habitus B, D ventral habitus E head F antenna G fore leg H hind leg I aedeagus. Scale bars: 1 mm (A-D); 0.1 mm (E, I); 0.5 mm (F-H).

Figure 2. Diagnostic characters of Bryaxis grandinodus sp. nov. (A, C) and B. koltzei (Reitter) (B, D). A, B antennal scapes and pedicels C, D protibiae. Scale bars: 0.1 mm.

Figure 11. Collection localities. Bryaxis grandinodus sp. nov. (blue pentagon); B. uljinensis sp. nov. (purple cross); B. fabaiformis sp. nov. (sky-blue star); B. girinensis sp. nov. (green diamond); B. nemorosus sp. nov. (navy hexagon); B. mahunkai Loebl (yellow square); B. koltzei (Reitter) (red circle); B. kimjongkuki Nomura & Lee (orange triangle).