Drusilla (Drusilla) flagellata, Assing, 2015

Assing, Volker, 2015, New species and additional records of Lomechusini from the Palaearctic region, primarily from China (Coleoptera: Staphylinidae: Aleocharinae), Beiträge Zur Entomologie = Contributions to Entomology 65 (2), pp. 243-262 : 249-251

Drusilla (Drusilla) flagellata spec. nov.

( Figs 14–25 )

Type material: Holotype ♂: “ CHINA (Yunnan) Dali Bai Aut. Pref. , Wuliang Shan , 20 km NW Weishan 1900 m (creek valley, under bank vegetation, stones, gravel) 25°19'58"N, 100°07'59"E, 17.IX.2009 D.W. Wrase [58] / Holotypus ♂ Drusilla flagellata spec. nov. det. V. Assing 2015” ( cAss).

Paratypes: 4 ♂♂, 2 ♀♀: same data as holotype (cSch, cAss); 1 ♂, 1 ♀: same data, but leg. Schülke (cSch); 1 ♂: “ CHINA (Yunnan) Lincang Pref., Xue Shan , 48 km N Lincang 2070 m, 24°19'03"N, 100°07'13"E (slope close to small pond, in loamy soil, plant roots) 12.IX.2009, D.W. Wrase [45]” (cAss) .

Etymology: The specific epithet (Latin, adjective) alludes to the conspicuously long flagellum in the internal sac of the aedeagus.

Description: Body size variable; body length 4.5–6.5 mm; length of forebody 2.2–2.7 mm. Coloration: head, pronotum, and abdomen blackish; elytra dark-yellowish, with the scutellar region and the postero-lateral angles extensively infuscate; legs pale-yellowish, with the apices of the femora more or less distinctly infuscate; antennae black; maxillary palpi reddish to reddish-brown, with the terminal palpomere yellow.

Head ( Figs 14–15 ) approximately 1.2 times as broad as long; dorsal surface with scattered and very fine punctation, without microsculpture, and glossy. Eyes large and bulging, much longer than distance from posterior margin of eye to posterior constriction of head. Antenna ( Fig. 16 ) 2.0– 2.3 mm long; antennomeres III–X gradually increasing in width; antennomere X approximately as long as broad.

Pronotum ( Figs 14–15 ) 1.02–1.06 times as broad as long and 1.06–1.09 times as broad as head, broadest at anterior angles; posterior angles obtusely marked; posteriorly with small impression of more or less triangular shape; midline with narrow, deep, and sharply delimited furrow extending from posterior impression cephalad, but not reaching anterior margin of pronotum; punctation dense and distinct, not granulose, subject to weakly pronounced sexual dimorphism; interstices without microsculpture and glossy.

Elytra ( Figs 14–15 ) approximately 0.9 times as long as pronotum; humeral angles marked; punctation dense, similar to that of pronotum. Hind wings fully developed. Metatarsomere I nearly as long as the combined length of II–IV.

Abdomen ( Fig. 17 ) narrower than elytra; tergites III– VII without sexual dimorphism; anterior impressions of tergites III–V and posterior margins of tergites III–VI with fine punctation, remainder of tergal surfaces with scattered and conspicuously sparse punctation, nearly impunctate; posterior margin of tergite VII with palisade fringe.

♂: pronotum ( Fig. 14 ) with extensive, but not very deep median impression with somewhat denser punctation; elytra in large males each with conspicuous oblong and oblique elevation ( Fig. 14 ); tergite VIII ( Fig. 18 ) strongly transverse and with distinctly serrate posterior margin; sternite VIII ( Fig. 19 ) transverse, posterior margin truncate in the middle; median lobe of aedeagus ( Figs 20–21 ) 1.0 mm long and of highly distinctive morphology, laterally somewhat flattened, with short ventral process, and with long flagellum in internal sac; paramere ( Fig. 22 ) very small, approximately 0.55 mm long, little more than half as long as median lobe.

♀: pronotum ( Fig. 15 ) flattened, but not impressed in the middle; tergite VIII ( Fig. 23 ) strongly transverse, posterior margin with a triangular projection on either side; sternite VIII ( Fig. 24 ) distinctly shorter and more transverse than that of male, posterior margin convex; spermatheca long and of distinctive shape ( Fig. 25 ).

Intraspecific variation: Body size and the modifications of the male elytra are subject to remarkable intraspecific variation. The elevations on the male elytra are fully pronounced only in the holotype, weakly pronounced in one, barely noticeable in two, and absent in three males.

Comparative notes: This species is characterized particularly by the modifications of the male elytra, the shapes of the male and female tergites VIII, and above all by the conspicuous morphology of the aedeagus and the distinctive shape of the spermatheca. For additional characters separating it from the sympatric and syntopic D. palata see the comparative notes in the following section.

Distribution and natural history: The known distribution is confined to two localities in West Yunnan. The specimens were collected on and near the bank of a stream and near a pond at altitudes of 1900 and 2070 m, in one locality together with D. palata . Two paratypes are slightly teneral.

Figures

Figs 14–25: Drusilla flagellata spec. nov.: male forebody (14); female forebody (15); antenna (16); male abdomen (17); male tergite VIII (18); male sternite VIII (19); median lobe of aedeagus in lateral and in ventral view (20–21); paramere (22); female tergite VIII (23); female sternite VIII (24); spermatheca (25). Scale bars: 14–17: 1.0 mm; 18–24: 0.5 mm; 25: 0.2 mm.