Pseudotachinus bilobus Yin and Li, 2018

Yin, Zi-Wei & Li, Li-Zhen, 2018, A new species and an additional record of Pseudotachinus Cameron from China (Coleoptera: Staphylinidae: Tachyporinae), Zootaxa 4425 (3), pp. 567-574 : 568-569

Pseudotachinus bilobus Yin and Li , new species

( Figs 1–5 )

Type material (17 exs). Holotype: CHINA: ♂: ‘China: Guizhou, Libo County (荔波县), Maolan N. R. (茂兰自 然保护区), Bizuo (必左) , 25°17’16’’N, 108°04’18’’E, 480–510 m, 27.iv.2017, mixed leaf litter, sifted, R.- X. Jiang et al. leg.’ ( SNUC). Paratype: CHINA: 6 ♂♂, 3 ♀♀: same data as the holotype; 1 ♂: ‘ China: Guizhou, Libo County, Da-qi-kong Park (大七孔景区) , ca. 25°17’ N, 107°44’, 400–450 m, sifted, 18.vii.2017, Z.- W. Yin leg.’; 1 ♂, 5 ♀♀: ‘ China: Guangxi, Hechi City, Mulun N. R., 25°8’54’’N, 106°02’37’’ E, 350–450 m, 24.vii. 2015, mixed leaf litter, sifted, J.-Y. Hu et al. leg.’ (all in SNUC)

Comparative diagnosis. Pseudotachinus bilobus is quite distinct among the genus, and can be readily separated from all congeners by a unique combination of the following features: 1) dorsal surface of the body completely lacks microsculpture 2) the color of the pronotal lateral margins is much lighter than that of the disc, 3) the elytra are markedly transverse (EW / EL = 1.48–1.60), 4) the male sternite VII lacks rows of transparent setae along the posterior margin, 5) the posterior margin of male tergite VIII is angularly protruding posteriorly at middle, 6) the median lobe of female tergite VIII is about as wide as lateral lobes, and 7) the female sternite VIII lacks well-defined median pair of lobes at the posterior margin.

Description. Male. Body ( Fig. 1A ) flattened, moderately stretched. Measurements: TBL 4.5–5.84 mm, FBL 3.61– 3.39 mm, HL 0.71–0.73 mm, HW 1.01–1.02 mm, EyL 0.26–0.33 mm, AnL 1.95–2.17 mm, PL 1.23–1.40 mm, PW 2.18–2.48 mm, EL 1.40–1.59 mm, EW 2.23–2.49 mm. Head, pronotal disc, elytra, and most parts of abdomen dark-brown, mouthparts, antennae, pronotal lateral margins, apex of abdomen, and legs reddish-brown.

Head ( Fig. 2A ) strongly transverse, finely and sparsely punctate, lacking microsculpture; eyes hemispherical, roundly protruding laterally, areas mesal to eyes longitudinally impressed ( Fig. 2A ), lateral area of genae with transverse microsculpture ( Fig. 2B ); antennae ( Fig. 1A ) elongate, all antennomeres much longer than wide; antennomeres I–IV lacking dense, fine setae, which are present on antennomeres V–XI. Pronotum ( Figs 1A , 2C ) markedly transverse (PI = 1.77–1.83), flattened; longitudinal impressions broad and shallow, present at anterior 3/4 of pronotal length; anterior corners broadly rounded; posterior corners strongly protruding posterolaterally; lateral margins clearly furrowed, impression slightly narrowing anteriorly and posteriorly; whole surface of pronotum finely punctate, smooth, lacking microsculpture. Scutellum lacking microsculpture. Elytra ( Fig. 1A ) strongly transverse (EI = 1.47–1.59), about as broad as pronotum; punctures ( Fig. 2D ) much stronger than those of head and pronotum; lacking microsculpture. Hind wings fully developed. Lateral area of prosternum ( Fig. 2E ) with small tuft of fair hair; mesoventrite ( Fig. 2E ) with dense transverse microsculpture, median carina thin and slightly raised ( Fig. 2F ). Protarsi ( Fig. 2G ) much broader than meso- and metatarsi. Abdomen lacking microsculpture; with slightly elongate punctures on segments IV–VI ( Figs 1A , 2H ), which are about as dense and strong as those of elytra, punctures on segments VII–VIII finer; tergite VIII ( Fig. 3A–B ) with four short lobes separated by short angularly rounded incisions at posterior margin; tergite IX ( Fig. 3C ) divided laterally to two lobes, each apically with long, spiniform macrosetae; posterior margin of sternite VII ( Fig. 3D ) broadly and shallowly emarginate at middle, lacking row of transparent bristles (bristles present in other congeners); posterior emargination of sternite VIII ( Fig. 3E–F ) angularly protruding posteriorly at middle; sternite IX ( Fig. 3G ) rounded at apex, with several very long bristles. Aedeagus ( Fig. 3H–I ) strongly elongate, parameres narrow, and broadly separated at base, apices tapering in dorsal and ventral view, slightly curved ventrally in lateral view; central part of endophallus ( Fig. 3J ) almost symmetric.

Female. General habitus ( Fig. 1B ) similar to male; size generally larger. Measurements: TBL 5.2–6.17 mm, FBL 3.34–4.0 mm, HL 0.73–0.88 mm, HW 1.08–1.20 mm, EyL 0.27–0.33 mm, AnL 2.0– 2.61 mm, PL 1.25–1.43 mm, PW 2.35–2.56 mm, EL 1.44–1.70 mm, EW 2.31–2.61 mm. Tergite VIII ( Fig. 4A–B ) tri-lobed, with median lobe longer than and about as broad as lateral lobes; sternite VIII ( Fig. 4C–D ) with only two distinct lobes at posterior margin, median and outer pairs of lobes largely reduced, apices of median lobes each with apical rim consisting of 10 transparent bristles; segments IX–X and styli as in Fig. 4E .

Distribution. China: Guizhou, Guangxi ( Fig. 5 ).

Etymology. The specific epithet refers to the presence of only two well-developed lobes at the posterior margin of female sternite VIII, which is an unusual character state in the genus.

Figures

FIGURE 1. Dorsal habitus of Pseudotachinus bilobus sp. n. A. Male. B. Female. Scale bars: 1 mm.

FIGURE 2. Morphology of Pseudotachinus bilobus sp. n. A. Head dorsum. B. Head venter. C. Right half of pronotum. D. Right elytron. E. Prosternum, and meso- and metaventrites. F. Central part of mesoventrite, showing median carina. G. Protarsus. H. Tergites IV–V, showing punctation. Scale bars: 1 mm in E; 0.5 mm in A–D, F; 0.3 mm in H; 0.2 mm in G.

FIGURE 3. Male diagnostic features of Pseudotachinus bilobus sp. n. A. Tergite VIII. B. Apex of tergite VIII, enlarged. C. Tergites IX+X. D. Sternite VII. E. Sternite VIII. F. Apex of sternite VIII, enlarged. G. Sternite IX. H–I. Aedeagus, in lateral (H) and ventral (I) view. J. Apical portion of aedeagus. Scale bars: 1 mm in E; 0.5 mm in A, C–E, G–I; 0.2 mm B, F, J.

FIGURE 4. Female diagnostic features of Pseudotachinus bilobus sp. n. A. Tergite VIII. B. Apex of tergite VIII, enlarged. C. Sternite VIII. D. Apex of sternite VIII, enlarged. E. Segments IX–X and styli. Scale bars: 1 mm in E; 0.5 mm in A, C; 0.2 mm B, D–E.

FIGURE 5. Distribution of Pseudotachinus species (modified from Schülke 2016). 1—P. besucheti, 2—P. pseudoniger, 3—P. niger, 4—P. assingi, 5—P. bilobus sp. n. Circle: published records; square: new data; red circle represents the doubtful record of P. niger from northern Myanmar.