Micrillus virgatus, Assing, 2018

Assing, Volker, 2018, A revision of Palaearctic and Oriental Scymbalium and Micrillus III. New species, new combinations, and additional records (Coleoptera: Staphylinidae: Paederinae), Linzer biologische Beiträge 50 (2), pp. 977-996 : 983-984

Micrillus virgatus nov.sp. ( Figs 9-19 )

T y p e m a t e r i a l: Holotype ♂: " CAMBODIA - Kampong Chhnang prov., Kampong Chhnang env., Toul Ompel , 12°14'14''N, 104°41'15''E, light trap, 19+ 21.V.2018, leg. Bernardi, Kong & Rossi / Holotypus ♂ Micrillus virgatus sp. n., det. V. Assing 2018" (cAss) . Paratypes: 24♂♂, 20♀♀: same data as holotype (cAss) ; 1♂: "S-THAIL, Betong 1993, Gunung Cang dun vill., Yala dist. , 25.3.-22.4., leg. Horak & Strnad" ( NHMW) .

E t y m o l o g y: The specific epithet is an adjective derived from the Latin noun virga (rod) and alludes to the long basal sclerotized structure in the internal sac of the aedeagus.

D e s c r i p t i o n: Body length 8.0- 9.5 mm; length of forebody 4.3-5.5 mm. Habitus as in Fig. 10 . Coloration: body reddish to reddish-brown, with the elytra usually somewhat paler; legs with the femora pale-reddish to yellowish-brown, the tibiae and tarsomeres I-IV dark-reddish to brown, and tarsomeres V yellow; antennae reddish, with the apical antennomeres often more or less extensively paler and with the apex of antennomere XI yellowish.

Head ( Fig. 11 ) approximately as broad as long; integument dorsally and laterally with dense and very fine punctation bearing short, fine, pale, and depressed setae, and with scattered macropunctures bearing long and black erect setae in lateral and anterior dorsal portions; median and anterior dorsal portions with sparser micropunctation. Eyes 0.5-0.7 times as long as postocular region in dorsal view. Antenna ( Fig. 12 ) long and very slen- der, approximately 4 mm long; antennomeres IV-X strongly oblong, of gradually decreasing length; IV approximately four times as long as broad; X approximately twice as long as broad. Maxillary palpus slender, apical palpomere of slender conical shape, slightly more than half as long as maxillary palpomere III.

Pronotum ( Fig. 11 ) 1.05-1.10 times as long as broad and approximately 0.95 times as broad as head; lateral margins straight, distinctly converging posteriad in dorsal view; posterior margin broadly and weakly concave; punctation very fine and dense; on either side of middle with dorsal series each composed of 2-6 macropunctures; midline without impunctate median band.

Elytra ( Fig. 11 ) approximately 0.9 times as long as pronotum; punctation extremely fine and extremely dense, rendering the surface matt. Hind wings fully developed. Protarsomeres I–IV distinctly dilated. Metatarsomere I slightly longer than the combined length of II and III.

Abdomen ( Fig. 13 ) approximately as broad as elytra; tergites with very fine and extremely dense micropunctation bearing short and pale depressed pubescence and with macropunctures bearing very long black setae at posterior margins and on disc; posterior margin of tergite VII with palisade fringe; tergite X and sternite IX very small; posterolateral processes of segment IX approximately twice as long as tergite X.

♂: posterior excision of sternite VIII concave ( Fig. 18 ); aedeagus ( Figs 14-17 , 19 ) approximately 0.95 mm long, symmetric, and weakly sclerotized; internal sac with long rod-like structure basally and with membranous structures apically.

C o m p a r a t i v e n o t e s: This species is characterized particularly by its slender body with long and slender legs and antennae, a posteriorly distinctly narrowed pronotum, and by the male sexual characters. The aedeagus is readily distinguished from those of other species of the M. badius group by its larger size alone.

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 currently known distribution is confined to two localities, one in Cambodia and one in South Thailand. The characteristics and collection data of the type locality ( Fig. 9 ) are identical to those of Scymbalium rossii . They suggest that M. virgatus is associated with wetlands.

Figures

Fig. 9: Type locality of Scymbalium rossii, Micrillus virgatus, M. kongi, and M. coloratus. Photo: Walter Rossi.

Figs 10-17: Micrillus virgatus: (10) habitus; (11) forebody; (12) antenna; (13) abdomen; (14-17) aedeagus in lateral and in ventral view of males from Thailand (14-15) and Cambodia (16-17). Scale bars: 10-13: 1.0 mm; 14-17: 0.5 mm.

Figs 18-24: Micrillus virgatus (18-19) and M. hamatus (20-24): (18, 21) male sternite VIII; (19) basal portion of aedeagus in lateral view; (20) habitus; (22-23) aedeagus in lateral and in ventral view; (24) apex of ventral process in lateral view. Scale bars: 20: 1.0 mm; 18, 21-23: 0.5 mm; 19, 24: 0.1 mm.