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

Figs 8 , 9B, D, F

Type materials

(N = 5, 4 ♂♂, 1 ♀). Holotype male. "Korea: Jeonnam Prov. Mt. Doksil, Gageo island. Gageodo-gil, Heuksan-myeon, Sinan-gun, 13 Jul 2021, 34°05'06.1"N, 125°06'17.4"E, 468 m, sifting leaf & soil litter, J.-W. Seo" (NIBR). Paratype. 1♂ (CBNUIC, slide mounted). "Korea: Jeonnam Prov. Mt. Doksil, Gageo island. Gageodo-gil, Heuksan-myeon, Sinan-gun, 13 Jul 2021, 34°05'06.1"N, 125°06'17.4"E, 468 m, sifting leaf & soil litter, J.-W. Seo". 1♂ (CBNUIC, dried). "Korea: Jeonnam Prov. Mt. Doksil, Gageo island. Gageodo-gil, Heuksan-myeon, Sinan-gun, 8 Jul 2020, 34°05'35.0"N, 125°06'25.0"E, 590 m, sifting leaf & soil litter, T.-Y. Jang". 1♂ (CBNUIC, dried). "Korea: Jeonnam Prov. Mt. Doksil, Gageo island. Gageodo-gil, Heuksan-myeon, Sinan-gun, 8 Jul 2020, 34°04'40.0"N, 125°06'23.0"E, 540 m, sifting leaf & soil litter, U.-J. Byeon, T.-Y. Jang". 1♀ (CBNUIC, dried). "Korea: Jeonnam Prov. Mt. Doksil, Gageo island. Gageodo-gil, Heuksan-myeon, Sinan-gun, 7 Jul 2020, 34°04'34.7"N, 125°06'28.8"E, 534 m, sifting leaf & soil litter, T.-Y. Jang".

Diagnosis.

Elongated head with small eyes situated on mid-length of head (Fig. 8E , arrow).

Description.

Body reddish brown, antennae, maxillary palpi, legs slightly lighter than body, length 1.57-1.58 mm, maximum width 0.61-0.67 mm (Fig. 8A-D ). Setae on body yellowish. Head 1.15 times as long as wide (Fig. 8E ). Frons with U-shaped impression between antennal tubercles; frontal foveae absent; frontal rostrum distinct anteriorly. Vertex weakly convex; longitudinal carina absent; vertexal foveae small. Eyes reduced with 9 facets. Maxillary palpi moderately developed; palpomeres II smooth; III with tubercles; palpomere IV 0.24-0.28 mm long and about 3.06-3.24 times as long as wide, subcylindrical pseudosegment at apex. Antennae about 0.61-0.68 mm long; scapes subcylindrical and elongated, 2-2.18 times as long as pedicels, without modification; pedicels subcylindrical, 1.38-1.40 times as long as wide; antennomere III 1.67-1.72 times as long as wide; IV-VII subequal in length; VIII subglobose as long as wide; IX 0.82-0.86 times as long as wide; X transverse, 0.64-0.65; XI largest, pointed at apex, 1.76-1.84 times as long as wide (Fig. 8F ). Pronotum 0.85-0.89 times as long as wide and widest at basal 2/3, lateral antebasal foveae connected by antebasal sulcus. Elytra slightly convex, 0.87 times as long as wide and widest at basal 1/3, each elytron with two basal foveae and subhumeral fovea. Legs slender; protibiae without spine (Fig. 8G ); metatibiae with spine on apical (Fig. 8H , arrow). Aedeagus robust, 0.53 mm long and 1.79 times as long as wide; penis bulbous and dorsal diaphragm small, transversely ovoid; parameres symmetrical, each bearing two setae; endophallus comprising simple strut basally and two symmetrical struts curved along with parameres, thickened basally (Fig. 8I ).

Sexual dimorphism. Female metatibial spines absent.

Remarks.

Adults of this species are similar to that of Bryaxis girinensis Choi, Park, Lee & Park sp. nov. in the shape of antennomeres IV-XI (Figs 7D , 8F ). However, they can be distinguished by having angular tempora much longer than the eyes (Fig. 9F ), smooth maxillary palpomere II (Fig. 9B ), unadorned antennal scapes and pedicels (Fig. 8F ), slender protibiae without a spine (Fig. 9D ), and an endophallus composed of three long struts (Fig. 8I ).

Etymology.

The specific epithet is the Latin word Bryaxis nemorosus ("wooded, shady", masculine) that refers to habitat where the types collected.

Habitat.

Specimens of this species were collected by sifting leaf and soil litter in wet forest with dense canopy, which is located on an island.

Distribution.

Korea (Gageo island, Sinan-gun, Jeollanam-do).

Figures

Figure 7. Bryaxis girinensis Choi, Park, Lee & Park, sp. nov. A dorsal habitus B ventral habitus C head D antenna E fore leg F hind leg G aedeagus. Scale bars: 1 mm (A, B); 0.1 mm (C, G); 0.5 mm (D-F).

Figure 8. Bryaxis nemorosus 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 9. Diagnostic characters of Bryaxis girinensis sp. nov. (A, C, E) and B. nemorosus sp. nov. (B, D, F). A, B maxillary palpi C, D protibiae E, F heads. Scale bars: 0.1 mm.