Drusilla perforans, Assing & V, 2015

Assing, Volker & V, North, 2015, On the Lomechusini fauna of Vietnam (Coleoptera: Staphylinidae: Aleocharinae), Linzer biologische Beiträge 47 (2), pp. 1257-1282 : 1261-1270

publication ID	https://doi.org/ 10.5281/zenodo.5282217
persistent identifier	https://treatment.plazi.org/id/03A2856A-FF89-A31A-4B99-FCF0E333FDB8
treatment provided by	Marcus
scientific name	Drusilla perforans
status	sp. nov.

Treatment

Drusilla perforans View in CoL nov.sp. ( Figs 5-7 View Figs 1-9 , 24-26 View Figs 19-26 , 60 View Fig )

T y p e m a t e r i a l: Holotype 3: "N-Vietnam - 10 km NW Sa Pa, 22°22'26''N, 103°45'27''E, 1850 m, stream valley, 8.VIII.2013, V. Assing [9+2] / Holotypus 3 Drusilla perforans sp. n., det. V. Assing 2015" (cAss). Paratypes: 233, 2♀♀: same data as holotype (cAss).

E t y m o l o g y: The specific epithet is the present participle of the Latin verb perforare (to pierce) and alludes to the claw-shaped internal structures of the aedeagus.

D e s c r i p t i o n: Body length 4.5-5.1 mm; length of forebody 2.1-2.2 mm. Coloration: head and pronotum reddish ( Fig. 5 View Figs 1-9 ); elytra brown to dark-brown ( Fig. 5 View Figs 1-9 ); abdomen ( Fig. 7 View Figs 1-9 ): paratergites III-VI yellowish in anterior half and blackish in posterior half; tergites III-IV reddish to yellowish-brown; tergite V of similar coloration as tergites III- IV or somewhat darker in posterior half; tergite VI dark-brown, except for the diffusely yellowish lateral margins; tergite VII dark-brown with broadly yellowish to reddish posterior margin; segments VIII-X dark-yellowish; legs pale-yellowish, with the apical third to two-fifths of the metafemora broadly infuscate; antennae ( Fig. 6 View Figs 1-9 ) dark-brown with antennomeres I-II and the base of III yellowish and the apical 1-3 antennomeres reddish; maxillary palpi yellowish.

Head ( Fig. 5 View Figs 1-9 ) weakly oblong, approximately 1.1 times as long as broad, broadest across eyes; postero-lateral outline between eyes and posterior constriction very weakly convex in dorsal view; dorsal surface with sparse and extremely fine punctation. Eyes large and strongly convex, slightly longer than distance from posterior margin of eye to posterior constriction. Antenna 2.1-2.3 mm long and shaped as in Fig. 6 View Figs 1-9 .

Pronotum ( Fig. 5 View Figs 1-9 ) approximately 1.02 times as broad as long and 1.01-1.04 times as broad as head, broadest anteriorly; lateral margins distinctly sinuate in dorsal view; posterior angles obtusely marked; median portion impressed; midline with distinct median furrow reaching neither anterior nor posterior margins; punctation dense, rather coarse, and sexually dimorphic.

Elytra ( Fig. 5 View Figs 1-9 ) approximately as long as pronotum; punctation very dense, with the interstices reduced to narrow ridges, and sometimes weakly defined or even partly confluent. Hind wings fully developed. Metatarsomere I of very variable length, relatively short and slightly longer than II (much shorter than the combined length of II and III) to long and approximately as long as the combined length of II and III.

Abdomen ( Fig. 7 View Figs 1-9 ): tergites III-V with deep, tergite VI with very shallow anterior impressions; tergites III-VI with a baso-lateral puncture on either side; tergites III-IV with a median pair of punctures; tergites III-VII otherwise impunctate, except for few setiferous punctures near posterior margins; posterior margin of tergite VII with palisade fringe.

3: pronotum with more pronounced median impression and with somewhat granulose punctation; posterior margin of tergite VIII truncate in the middle; sternite VIII somewhat longer than tergite VIII and with convex posterior margin; median lobe of aedeagus ( Figs 24-25 View Figs 19-26 ) 0.66-0.69 mm long and of distinctive shape; internal sac with a pair of clawshaped sclerotized structures (ventral view).

♀: pronotum with less pronounced median impression and with non-granulose punctation; posterior margin of tergite VIII indistinctly truncate in the middle; posterior margin of sternite VIII weakly convex; spermatheca of distinctive shape ( Fig. 26 View Figs 19-26 ).

C o m p a r a t i v e n o t e s: Drusilla perforans differs from all other Drusilla species by the morphology of the aedeagus and the shape of the spermatheca, as well as by the coloration. It is additionally distinguished from D. zyrasoides DVOŘÁK, 1988 , the only other species of the genus previously recorded from Vietnam, by different coloration ( D. zyrasoides : head, pronotum, and abdomen blackish; elytra distinctly bicoloured, darkyellowish with the postero-lateral portions blackish), the absence of a sexual dimorphism of the head, the oblong head, and numerous other characters (see Figs 41-50 View Figs 35-43 View Figs 44-53 ). For illustrations of other geographically close Drusilla species recorded from China, Thailand, and Laos see ASSING (in press a), MARUYAMA (2004a, 2004b), PACE (1986, 1992, 1993, 1998, 2000, 2003, 2004a, 2012a, 2012b).

D i s t r i b u t i o n a n d n a t u r a l h i s t o r y: The type specimens were sifted and roots from moist leaf litter in a steep stream valley with deciduous trees at an altitude of 1850 m ( Fig. 60 View Fig ), approximately 10 km to the northwest of Sa Pa, North Vietnam. An association with ants or termites was not observed.