Gnathymenus crucifer, Assing, 2015

Assing, Volker, 2015, New species and additional records of Dolicaonina from Ecuador (Coleoptera: Staphylinidae: Paederinae), Linzer biologische Beiträge 47 (2), pp. 1119-1132 : 1123-1124

Gnathymenus crucifer nov.sp. ( Figs 10-16 )

T y p e m a t e r i a l: Holotype 3: " ECUADOR - Zamora Chinchipe, Estacion Cientifica S. Francisco, 3°59'S, 79°05'W, 1900m, 10-14.VIII.2014, Rossi / Holotypus 3 Gnathymenus crucifer sp. n. det. V. Assing 2014" (cAss). Paratypes: 333, 17♀♀: same data as holotype (cAss, MNHUB).

E t y m o l o g y: The specific epithet (adjective: carrying a cross) alludes to the shape of the dorsal plate of the aedeagus.

D e s c r i p t i o n: Body length 4.5-5.5 mm; length of forebody 2.5-2.6 mm. Coloration distinctive: body black with bright-reddish pronotum; legs bicoloured with the forelegs yellowish, and the mid- and hindlegs blackish-brown with yellowish tarsi; antennae yellowish; maxillary palpi blackish.

Head ( Fig. 10 ) transverse, 1.05-1.10 times as broad as long, widest across eyes, tapering behind eyes; dorsal surface with four coarse punctures forming a square or a transverse rectangle in median portion and with few scattered punctures in lateral and in anterior portions; interstices without microsculpture. Eyes rather large and convex, 0.6-0.8 times as long as distance from posterior margin of eye to posterior constriction in dorsal view. Antenna approximately 1.1 mm long.

Pronotum ( Fig. 11 ) approximately 1.2 times as long as broad and 1.05 times as broad as head, more strongly tapering posteriad than anteriad; the broadly impunctate midline laterally delimited by a dorsal series of approximately eight relatively coarse punctures on either side; lateral portions with sparse punctation; interstices without microsculpture.

Elytra ( Fig. 12 ) approximately as long as, or slightly longer than, pronotum and with marked humeral angles; punctation sparse and shallow; interstices without microsculpture. Hind wings fully developed. Metatarsomere I aproximately as long as II.

Abdomen distinctly narrower than elytra; segments III-VI with distinct paratergites; punctation fine and conspicuously sparse; interstices with fine transverse microsculpture; posterior margin of tergite VII with palisade fringe; posterior margin of tergite VIII strongly convex.

3: sternites IV and V each with a smooth, glossy, shallow postero-median impression ( Fig. 11 ); sternite VI with a pronounced, deep and sharply delimited postero-median impression ( Fig. 11 ); sternite VII ( Fig. 12 ) approximately 1.35 times as broad as long and with pronounced and sharply delimited U-shaped postero-median impression, this impression with conspicuous median carina, posterior excision shaped like a bottle-head; sternite VIII ( Fig. 13 ) approximately 1.15 times as long as broad and with conspicuously deep median incision, this incision nearly reaching anterior margin of sternite; aedeagus ( Figs 14-16 ) approximately 0.8 mm long, with ventral process and dorsal plate of distinctive shapes, the latter long, apically somewhat resembling a cross or a clover-leaf in dorsal view and extending beyond apex of ventral process; parameres completely reduced.

C o m p a r a t i v e n o t e s: The new species is distinguished from all its congeners by the distinctive coloration, the distinctive morphology of the aedeagus and by the distinctive male secondary sexual characters. Using the key to females (based on external characters) in HERMAN (1981), G. crucifer would key out at couplet 84, together with G. tungus HERMAN, 1981 from Ecuador, from which it is distinguished by the completely different male sexual characters, the different coloration ( G. tungus : all legs yellowish; middle of antennae darkened; only penultimate palpomere of maxillary palpus darkened), the much sparser punctation of the head and abdomen, and by slightly larger body size. For illustrations of the male sexual characters of G. tungus see HERMAN (1981).

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: Thisspeciesisthefirstrepresentative of the genus to be recorded from southern Ecuador. The type locality is situated in Zamora Chinchipe, some 10 km to the east of Loja in the extreme north of Podocarpus National Park. The specimens were collected in a cloud forest at approximately 1900 m by canopy fogging (ROSSI pers. comm.), suggesting that G. crucifer may be arboricolous. Remarkably, only four in a total of 21 specimens are males.

Figures

Figs 10-16: Gnathymenus crucifer nov.sp.: (10) forebody; (11) segments III-VI of male abdomen in ventral view; (12) male sternite VII; (13) male sternite VIII; (14) aedeagus in lateral view; (15) ventral process of aedeagus in ventral view; (16) dorsal plate of aedeagus in dorsal view. Scale bars: 10-13: 0.5 mm; 14-16: 0.2 mm.