Drusilla bucina, Assing, 2019

Assing, Volker, 2019, Four new species and additional records of Lomechusini from Mindanao, Philippines (Coleoptera, Staphylinidae, Aleocharinae), Linzer biologische Beiträge 51 (2), pp. 789-802 : 791-792

Drusilla bucina nov.sp. (Figs 1-5, 18-20, 26, 33-34)

T y p e m a t e r i a l: Holotype ♂: " PHILIPPINES - Mindanao, Araibo, Pantukan, Compostela V., Candalaga Mts., 7°16'35''N, 126°10'13''E, 900 m, 4.V.2019, Shavrin / Holotypus ♂ Drusilla bucina sp. n. det. V. Assing 2019 " (cAss). Paratype ♀: " PHILIPPINES - Mindanao, Davao prov., Mt. Talomo, Catigan, 800-1000 m, 7°01'21''N, 125°22'31''E, 30.IV.-1.V.2019, Shavrin" (cAss).

E t y m o l o g y: The specific epithet (Latin, noun in apposition: trumpeter) alludes to trumpet-shaped distal portion of the spermatheca.

D e s c r i p t i o n: Body length 5.1-5.6 mm; length of forebody 2.4-2.6 mm. Habitus as in Fig. 1. Coloration: black with the humeral angles of the elytra, the antero-lateral portions of abdominal tergites III-VI, and the anterior halves of paratergites III-VI yellow; legs yellow with the apical halves of the femora infuscate; antennae blackish with the apical 2-3 antennomeres dark-yellow; maxillary palpi blackish with the apical palpomere pale-yellow.

Head (Fig. 2) approximately 1.15 times as broad as long; dorsal surface nearly impunctate and without distinct microsculpture, between eyes with an inversely V-shaped impression between eyes, in the middle somewhat elevated. Eyes large and bulging, longer than postocular portion in dorsal view. Antenna (Fig. 4) 2.3-2.6 mm long; antennomeres I strongly dilated apically (club-shaped), IV-X distinctly oblong, of gradually decreasing length, and XI elongate, three times as long as broad, and approximately as long as the combined length of IX and X.

Pronotum (Figs 2-3) 1.06-1.08 times as long as broad and 0.91-0.93 times as broad as head, broadest anteriorly; lateral margins sinuate in dorsal view; dorsal surface anteriorly with transverse glossy impression with very sparse punctation, and with narrow, but deep median sulcus posteriorly reaching a transverse and flatly C-shaped impression; punctation coarse and dense (except in antero-median portion), subject to sexual dimorphism.

Elytra (Fig. 2) 0.85-0.90 times as long as pronotum; punctation very dense, coarse, and partly rugose; interstices reduced to narrow ridges. Hind wings fully developed.

Abdomen (Fig. 5) without microsculpture, glossy; tergites III-VI with a transverse row of punctures across middle and one at posterior margin, otherwise impunctate; posterior margin of tergite VII with palisade fringe.

♂: pronotum with predominantly coarsely granulose punctation (Fig. 2); tergite VIII without evident modifications, posterior margin weakly convex; posterior margin of sternite VIII moderately convex; median lobe of aedeagus 0.55 mm long and shaped as in Figs 18-19; paramere 0.5 mm long, without evident modifications.

♀: pronotum (Fig. 3) predominantly with coarse and somewhat umbilicate punctation, granulose punctures present only in antero-lateral portions; tergite VIII ( Fig. 26 ) without evident modifications, posterior margin convex, in the middle weakly concave; sternite VIII strongly transverse, with weakly convex posterior margin; spermatheca (Fig. 20) with trumpet-shaped distal portion and with long and coiled proximal portion.

C o m p a r a t i v e n o t e s: Drusilla bucina is characterized particularly by the punctation pattern and by the primary sexual characters. It is distinguished from other congeners previously recorded from the Philippines as follows:

from D. bernhaueri (SCHEERPELTZ, 1934) (Luzon) by completely different coloration (D. bernhaueri: body yellow with dark head), different head shape (D. bernhaueri: temples acutely produced), and numerous other characters;

from D. butuanensis (BERNHAUER, 1916) (Mindanao) by larger size (D. butuanensis: 3 mm), completely different coloration (D. butuanensis: forebody reddish), much coarser and denser punctation of the elytra, and other characters;

from D. impressicollis (KRAATZ, 1857) (widespread in the Oriental region) by larger size (D. impressicollis: 3 mm), different coloration (D. impressicollis: pronotum reddishbrown and elytra yellowish to yellowish-brown), a differently shaped head, and other characters;

from D. laevicauda (BERNHAUER, 1903) (widespread in the Oriental region) by larger size (D. laevicauda: 3 mm), the coloration (D. laevicauda: pronotum and elytra brown), coarser and denser punctation of the pronotum and the elytra, and other characters;

from D. luzonica (BERNHAUER, 1915) (Luzon) by larger size (D. luzonica: 3.5 mm), the coloration of the legs (D. luzonica: legs uniformly yellow), a pronotum without a large impression on either side of the middle, and much denser punctation of the elytra;

from D. philippina (BERNHAUER, 1915) (Luzon) by larger size (D. philippina: 3 mm), the coloration of the elytra (D. philippina: elytra yellowish-brown), and coarse and dense punctation of the pronotum (D. philippina: pronotum with fine and moderately dense punctation);

from D. plicipennis (BERNHAUER, 1915) (Luzon) by larger size (D. plicipennis: 3 mm), completely different coloration (D. plicipennis: forebody reddish), much denser punctation of the elytra, the absence of tubercles on tergites IV-VII, and other characters;

from D. schawalleri KISTNER, 1994 (Leyte) by different coloration (D. schawalleri: body reddish-brown), a more slender pronotum (D. kistneri: pronotum broader than long), and by the shapes of the aedeagus and the spermatheca (see KISTNER 1994);

from the recently described D. shavrini ASSING, 2019, D. penicillata ASSING, 2019 , D. spiniventris ASSING, 2019, and D. breviuter ASSING, 2019 (all Mindanao) by the punctation pattern, the coloration, and the sexual characters. For illustrations of external and the sexual characters, as well as detailed descriptions of these species see ASSING (2019).

D i s t r i b u t i o n: The type specimens were collected in two localities in East Mindanao by sifting wet litter near running water in a secondary forest and in a stream valley at altitudes between 800-1000 m ( Figs 33-34 ).

Figures

Figs 26-32: Drusilla bucina (26), Zyras rasilis (27-29), and Z. nigrorufus (30-32): (26) female tergite VIII; (27-28, 30-31) median lobe of aedeagus in lateral and in ventral view; (29, 32) paramere. Scale bars: 0.2 mm.

Fig. 33: Locality Compostela Valley (photo: A. Shavrin).

Fig. 34: Locality Catigan (photo: A. Shavrin).