Drusilla (Drusilla) yunnanensis PACE, 1993

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 : 252-254

Drusilla (Drusilla) yunnanensis PACE, 1993

( Figs 34–45 )

Material examined: China: Yunnan: 3 ♂♂, 2 ♀♀, Yunnan , mountains S Jianshui, 23°25'N, 102°51'E, 1810 m, secondary forest margin, litter and various debris sifted, 22.VIII.2014, leg. Assing & Schülke (cSch, cAss) .

Comment: In the original description, which is based on a male holotype from “ Yunnan, Dali” and a female paratype from “ Yunnan, Kunming”, PACE (1993) describes the coloration as “...; uriti liberi primo e secondo giallo-rossicci; antenne brune con i due articoli basali di un rossiccio scuro; zampe gialle con ginocchia medie e posteriori di un rossiccio scuro”. The other characters specified in the very short original description are too vague to be of taxonomic use. Despite the differences in the coloration (see the redescription below), the examined material is undoubtedly conspecific with the holotype, as can be inferred from the identical shape of the median lobe of the aedeagus (compare Figs 40–41 and figures 144–145 in PACE 1993). The type specimens may be teneral. The illustration of the spermatheca ( PACE 1993: figure 141) of the paratype is misleading. In order to allow a reliable identification of this species, a redescription and new illustrations are provided.

Redescription: Body length 4.8–6.3 mm; length of forebody 2.3–2.6 mm. Coloration: body black, elytra with or without faint bronze hue; legs uniformly yellowish, rarely with the femoral apices indistinctly darker; antennae black, with antennomeres I–III slightly paler blackishbrown; maxillary palpi pale-brown to dark-brown, with the terminal palpomere yellow.

Head ( Figs 34–35 ) approximately 1.1 times as broad as long; punctation of dorsal surface subject to sexual dimorphism; interstices without microsculpture and glossy. Eyes large and bulging, much longer than distance from posterior margin of eye to posterior constriction of head. Antenna ( Fig. 36 ) 2.0– 2.1 mm long; antennomeres III–X gradually increasing in width; antennomeres VI–X transverse.

Pronotum ( Figs 34–35 ) approximately 1.06 times as broad as long and 1.10–1.13 times as broad as head, broadest at anterior angles; posterior angles obtusely marked; posteriorly with small transverse impression; midline with very fine line extending cephalad from posterior impression, but not reaching anterior margin of pronotum; punctation sexually dimorphic; interstices without microsculpture and glossy.

Elytra ( Figs 34–35 ) approximately 0.9 times as long as pronotum; humeral angles marked; punctation very dense, not very coarse, but much more distinct than that of pronotum. Hind wings fully developed. Metatarsomere I shorter than the combined length of II–IV.

Abdomen ( Fig. 37 ) approximately as broad as elytra; tergites III–VII without sexual dimorphism; anterior impressions of tergites III–V and anterior portion of tergite VI impunctate; tergite III with moderately sparse to very sparse fine punctation; tergites IV–VI with setiferous punctures at posterior margin, remainder of tergal surfaces with very sparse and minute punctures; tergite VII with sparse and fine punctation, posterior margin with palisade fringe.

♂: postero-median portion of head with moderately sparse, somewhat coarser punctures, remainder of dorsal surface with fine and sparse punctation; pronotum ( Fig. 34 ) with extensive, but not very deep median impression in posterior half; punctation of pronotum fine and moderately dense, postero-lateral edges of postero-median impression with coarser granulose sculpture; tergite VIII ( Fig. 38 ) strongly transverse and with distinctly serrate posterior margin, postero-lateral angles with more pronounced tooth on either side; sternite VIII ( Fig. 39 ) weakly transverse, posterior margin weakly convex in the middle; median lobe of aedeagus ( Figs 40–41 ) relatively small, approximately 0.65 mm long; paramere 0.6 mm long and shaped as in Fig. 42 .

♀: head ( Fig. 35 ) with extemely fine, barely noticeable sparse punctation; pronotum ( Fig. 35 ) somewhat depressed in posterior half, but without distinct impression (aside from the small posterior transverse impression); punctation of pronotum rather dense and fine, but more distinct than that of head; tergite VIII ( Fig. 43 ) strongly transverse, posterior margin weakly concave in the middle; sternite VIII ( Fig. 44 ) distinctly shorter and more transverse than that of male, posterior margin weakly convex; spermatheca 0.33 mm long, with large, apically truncate, and strongly sclerotized distal portion ( Fig. 45 ).

Comparative notes: Among the Drusilla species recorded from China, D. yunnanensis is characterized particularly by the dense punctation of the elytra, the fine punctation of the head and the pronotum, the impunctate anterior impressions of the abdominal tergites III–V, the male secondary sexual characters, the shape of the female tergite VIII, the morphology of the median lobe of the aedeagus, and the shape of the spermatheca.

Distribution and natural history: The currently known distribution is confined to three localities in Yunnan. MARUYAMA & KISHIMOTO (2002a) collected the species from trails of Lasius (Dendrolasius) spathepus WHEELER, 1910 and L. (D.) capitatus KUZNETSOV-UGAMSKY, 1927 . The examined specimens were sifted from litter and various debris at the margin of a secondary mixed forest at an altitude of 1810 m.

Figures

Figs 34–45: Drusilla yunnanensis: male forebody (34); female forebody (35); antenna (36); female abdomen (37); male tergite VIII (38); male sternite VIII (39); median lobe of aedeagus in lateral and in ventral view (40–41); paramere (42); female tergite VIII (43); female sternite VIII (44); spermatheca (45). Scale bars: 34–37: 1.0 mm; 38–39, 43–44: 0.5 mm; 40–42, 45: 0.2 mm.