Drusilla (Drusilla) watanabei MARUYAMA & KISHIMOTO, 2002

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 : 246-249

Drusilla (Drusilla) watanabei MARUYAMA & KISHIMOTO, 2002

( Figs 1–13 )

Material examined: China: Yunnan: 3 ♂♂, 1 ♀, mountains W Dongchuan, Sedan Snow Mountain Scenic Resort, 26°06'N, 102°55'E, 2620 m, secondary pine forest, litter, moss, and roots of herbs sifted, 14.VIII.2014, leg. Assing (cAss) .

Comment: The original description is based on 16 type specimens from two localities in Hubei and Hunan provinces ( MARUYAMA & KISHIMOTO 2002a). The authors did not find (and illustrate) a spermatheca, although the type series includes seven females. A full redescription is provided below.

Description: Relatively large species; body length 7.0– 7.8 mm; length of forebody 2.6–3.0 mm. Coloration: body black, with the posterior margins of the abdominal segments paler; legs with the tibiae and tarsi yellowish to dark-yellowish, the profemora blackish, the mesofemora blackish with the basal third yellowish, and the metafemora yellowish in basal half and infuscate in apical half; antennae reddish-yellow, with antennomere I weakly to distinctly infuscate; maxillary palpi dark-brown, with the terminal palpomere reddish-yellow.

Head ( Figs 1–2 ) with sexually dimorphic punctation and with fine and shallow microreticulation. Eyes distinctly shorter than distance from posterior margin of eye to posterior constriction of head. Antenna ( Fig. 3 ) 2.6–2.9 mm long and slender; all antennomeres at least weakly oblong. Pronotum ( Figs 1–2 ) 1.00–1.05 times as long as broad and 1.17–1.18 times as broad as head, broadest in anterior half; posterior angles weakly marked; near posterior margin with pronounced transverse impression; other impressions and punctation sexually dimorphic; interstices without microsculpture and glossy.

Elytra ( Figs 1–2 ) short, approximately 0.65 times as long as pronotum; humeral angles moderately marked; punctation sexually dimorphic; interstices without microsculpture. Hind wings reduced to short stubs extending slightly beyond posterior margin of elytra. Metatarsomere I elongate, approximately as long as the combined length of II–IV.

Abdomen ( Fig. 4 ) distinctly broader than elytra; tergites III–VIII with sexual dimorphism; punctation sexually dimorphic; anterior impressions of tergites III– VI impunctate; tergites with very weak, nearly obsolete transverse microsculpture; posterior margin of tergite VII with palisade fringe.

♂: lateral portions of dorsal surface of head with dense and rather coarse punctation, with the interstices narrower than diameter of punctures; frons, posterior portion, and the narrow midline of the head impunctate or nearly so ( Fig. 1 ); pronotum in posterior half with pronounced longitudinal elevation on either side, between these elevations with broadly flattened impression; median portion of pronotum somewhat shiny and with moderately dense and moderately coarse punctation, with the interstices as broad as, or broader than, diameter of punctures; lateral portions of pronotum practically matt, with very dense and coarsely granulose punctation, with the interstices narrower than diameter of punctures ( Fig. 1 ); elytra with dense and coarsely granulose punctation ( Fig. 1 ); abdominal tergite III ( Fig. 4 ) with a pronounced median tubercle of somewhat variable shape and with scattered fine punctures; tergites IV–VI each with a median pair of distinct granules near posterior margin, impunctate (or nearly so), except for some punctures at posterior margins; tergite VII with a pronounced median granule and numerous additional smaller granules in posterior half ( Fig. 4 ); tergite VIII ( Fig. 5 ) with densely granulose punctation and with distinct microreticulation, posterior margin broadly concavely excavate; sternite VIII ( Fig. 6 ) weakly transverse and with nearly truncate posterior margin; median lobe of aedeagus large, 1.0– 1.1 mm long, shaped as in Figs 7–8 ; paramere 0.9 mm long and shaped as in Fig. 9 .

♀: head ( Fig. 2 ) with sparse and very fine punctation, interstices much broader than diameter of punctures; pronotum ( Fig. 2 ) with weakly pronounced elevations in posterior half; punctation moderately fine, moderately dense, and non-granulose; elytra ( Fig. 2 ) with weakly granulose puncation; abdominal tergites III–V with fine and sparse punctation; tergite VI impunctate except for a median pair of setiferous punctures bearing long dark setae and additional punctures at posterior margin; tergite VII with a median pair of setiferous punctures bearing long dark setae and with additional fine and sparse punctation in posterior half; posterior margin of tergite VIII somewhat truncate, only indistinctly concave in the middle ( Fig. 10 ); sternite VIII ( Fig. 11 ) distinctly shorter and more transverse than that of male, posterior margin truncate; spermatheca very small in relation to body size, 0.25 mm long, and shaped as in Figs 12–13 .

Comparative notes: This highly distinctive species differs from other Drusilla species known from China by numerous characters, particularly its large body size, the long and slender antennae, the short elytra, the reduced hind wings, the male secondary sexual characters, and the male and female primary sexual characters.

Distribution and natural history: The known distribution now includes a total of three localities in Hubei, Hunan, and Yunnan provinces. The examined specimens were sifted from litter, moss, and the roots of herbs in a terraced secondary pine forest at an altitude of 2620 m. MARUYAMA & KISHIMOTO (2002a) found D. watanabei associated with the ant Lasius (Dendrolasius) spathepus WHEELER, 1910 .

Figures

Figs 1–13: Drusilla watanabei: male forebody (1); female forebody (2); antenna (3); male abdomen (4); male tergite VIII (5); male sternite VIII (6); median lobe of aedeagus in lateral and in ventral view (7–8); paramere (9); female tergite VIII (10); female sternite VIII (11); spermatheca in different aspects (12–13). Scale bars: 1–4: 1.0 mm; 5–11: 0.5 mm; 12–13: 0.2 mm.