Euconnus (s. str.) dulcis Sharp, 1886

Yin, Zi-Wei, Feng, Ting & Zhou, De-Yao, 2025, First report of subfamily Scydmaeninae (Coleoptera, Staphylinidae) from Shanghai, with description of two new species, ZooKeys 1231, pp. 133-143 : 133-143

Euconnus (s. str.) dulcis Sharp, 1886

Figs 1 , 4

Euconnus dulcis Sharp, 1886: 47; Hoshina 2019: 201. Type locality: Nagasaki.

Euconnus (s. str.) dulcis Sharp; Jałoszyński 2022: 3; Byeon et al. 2023: 321.

Euconnus chinensis Li, J. - K. & Wang, Z. - Y., 1993: 163 (nec. E. chinensis Franz, 1985: 114). Type locality: Ningguo. Syn. nov.

Euconnus cerastiventris Vit, 2006: 75 (replacement name for E. chinensis Li, J. - K. & Wang, Z. - Y.). Syn. nov.

Material examined

(5 exx.). • 1 ♂: ‘ China: Shanghai City, Minhang Dist. , 31°01'N, 121°28'E, alt. 4 m, 6. iv. 2014, Xiao-Bin Song leg. ’; • 2 ♀♀: ‘ China: Shanghai City, Songjiang Dist., East Sheshan , 9. iv. 2021, Xiao-Bin Song leg. ’; • 3 ♀♀: ‘ China: Shanghai City, Jiading Dist., Liudao , 31°29'38"N, 121°14'3"E, alt. 3 m, 3. x. 2023, Yin & Zhou leg. ’. (all in SNUC) .

Diagnosis.

Male. Body length 1.4–1.7 mm. Dorsum of body finely punctate. Thick bristles present on tempora and sides of pronotum, especially dense on tempora. Anterior margin of clypeus (Fig. 1 B ) angularly prominent at middle. Antenna elongate, club loosely formed by apical four moderately enlarged antennomeres, occupying about half of antennal length. Pronotum bell-shaped, with two asetose basolateral pits connected by shallow transverse impression. Each elytron with two closely-placed basal pits. Abdomen greatly modified (Fig. 1 C ), sternite 4 (VI) and 5 (VII) each with two posterolateral nodules directed posteromedially, area between nodules on sternite 4 filled with peg-like granules distributed roughly in two transverse rows. Aedeagus (Fig. 1 D, E ) with apical projection much longer than parameres; endophallus armature composed of group of symmetric sclerites; parameres each greatly broadened, bearing two long setae near apex and three similar setae along lateral margin. Female (Fig. 1 A ). External morphology similar to male. Abdomen unmodified. Spermatheca (Fig. 1 F ) spherical; spermathecal duct broadened at base.

Description.

See Vit (2006) and Jałoszyński (2022). Measurement for Shanghai population: male body length 1.48 mm; length / width of head 0.35 mm / 0.34 mm, pronotum 0.38 mm / 0.37 mm, elytra 0.78 mm / 0.63 mm, length of antenna 0.81 mm, club 0.42 mm, length of aedeagus 0.27 mm; female body length 1.49–1.53 mm; length / width of head 0.37–0.39 mm / 0.34–0.38 mm, pronotum 0.41–0.43 mm / 0.39–0.41 mm, elytra 0.86–0.88 mm / 0.67–0.71 mm, length of antenna 0.77–0.80 mm, club 0.36–0.38 mm, maximum diameter of spermatheca 0.27 mm.

Distribution.

East China: Anhui, Shanghai (Minhang, Songjiang, Jiading) (Fig. 4 A ); Japan: Honshu, Kyushu; South Korea: Jeju. New record for Shanghai.

Biology.

Adult specimens were obtained by sifting grass roots, and mixed bush and bamboo leaf litter (Fig. 4 B – D ).

Remarks.

This species exhibits a wide distribution across East Asia and is readily distinguishable by an angulate clypeus in both sexes, a sexually dimorphic abdomen in the male, and a distinctive morphology of the aedeagus. The descriptions and illustrations presented by Vit (2006) and Jałoszyński (2022) offer compelling evidence supporting the proposed synonymy. The spermatheca (Fig. 1 F ) of this species is illustrated for the first time.

Figures

Figure 1. Euconnus (s. str.) dulcis (B – E male A, F female) A dorsal habitus B head, in anterior view, showing clypeal angulation C sternites, showing modification on 4 (VI) and 5 (VII) D, E aedeagus, lateral (D) and ventral (E) F spermatheca, lateral. Scale bars: 0.5 mm (A); 0.2 mm (B, C); 0.1 mm (D, E); 0.05 mm (F).

Figure 4. Distribution and collecting circumstances of Euconnus species in Shanghai A distribution of the three species B – D collecting circumstance of E. dulcis at Minhang (B), Sheshan (C), and Liudao (D), E. imparitus sp. nov. at Quanjing Village (E), and E. magnoculus sp. nov. at Shanghai Zoo (F).