Keratodegnathus cornutus, Assing, 2019

Assing, Volker, 2019, On the Lomechusini fauna of the Palaearctic and Oriental regions. XXVI. New species, a new synonymy, and additional records (Coleoptera: Staphylinidae: Aleocharinae), Beiträge Zur Entomologie = Contributions to Entomology 69 (1), pp. 33-70 : 53

Keratodegnathus cornutus spec. nov.

urn:lsid:zoobank.org:act:042656C4-9410-4A3A-9648-037977E13C0C

(Figs 19–23, 114–117)

Type material: Holotype: “ MALAYSIA 2011 PAHANG, Cameron Highlands, Tanah Rata vill. env., 1500–1600 m, FIT, R. Hergovits leg. 4.iv.2011 / Holotypus Keratodegnathus cornutus sp. n., det. V. Assing 2017” ( MMB) . Paratype: same data as holotype (cAss) .

Etymology: The specific epithet (Latin, adjective) alludes to the horn-like processes of the mandibles.

Description: Body length 6.0– 6.6 mm; length of forebody 2.8–3.3 mm. Coloration (Figs 19–23): forebody black, except for the yellowish scutellum; abdomen palereddish; legs blackish-brown to black with slightly paler tarsi; antennae distinctly bicoloured, black with antennomeres X and XI pale-yellowish; maxillary palpi reddish.

Head (Figs 19–20) strongly transverse, sexually dimorphic; posterior margin concave in dorsal view; clypeus membranous; frons and vertex without punctation, without pubescence, and without microsculpture. Eyes large and strongly convex in cross-section, more than twice as long as postocular region in dorsal view. Antenna (Fig. 22) conspicuously elongate, 3.8–4.0 mm long; antennomeres IV–IX approximately three times as long as broad, X 2.5 times as long as broad, and XI five times as long as broad. Maxillary palpi slender, palpomere IV approximately four times as long as broad. Mandibles sexually dimorphic, with conspicuous horn-shaped processes dorsally.

Pronotum (Figs 19–20) of transversely trapezoid shape, broader anteriorly than posteriorly, 1.41–1.45 times as broad as long and 0.85–0.90 times as broad as head; lateral margins distinctly sinuate in dorsal view; disc with a transverse series of 4 punctures at anterior fourth and a pair of punctures in the middle, otherwise impunctate; lateral margins each with four very long and erect black setae; microsculpture absent.

Elytra (Figs 19–20) slightly longer and distinctly broader than pronotum; punctation fine and very sparse; interstices without microsculpture. Hind wings fully developed. Legs very long and slender; metatarsus nearly as long as metatibia; metatarsomere I nearly as long as the combined length of metatarsomeres II–IV.

Abdomen (Fig. 23) tapering from base to apex; tergite III with one, tergites IV–VII with two long black setae on either side, otherwise without setae; tergite VI with two additional setae in median portion of posterior margin; non-setiferous punctation absent; posterior margin of tergite VII with palisade fringe; tergite VIII with approximately 10–12 long black setae in posterior portion, posterior margin convex, not sexually dimorphic.

: head (Figs 19, 21) large, strongly transverse, with strongly concave posterior margin (dorsal view), distinctly impressed between eyes, and shallowly impressed in antero-lateral portion of frons; mandibles each with a conspicuous bifurcate antler-shaped process, these processes with ventral branch directed nearly horizontally forward and with a dorsal, nearly vertically upright branch; median lobe of aedeagus 0.7 mm long and shaped as in Figs 114–115; paramere (Fig. 116) nearly as long as median lobe, without conspicuous modification.

: head (Fig. 20) smaller and less transverse than in male, with more weakly concave posterior margin (dorsal view), less distinctly impressed between eyes, but with a marked impression in antero-lateral portion of frons on either side; mandibles each with one simple, curved, apically acute, and sub-erect process (shaped like a second set of mandibles); spermatheca (Fig. 117) with numerous thin coils, a small distal portion, and with a large balloonshaped structure.

Comparative notes: Previously, only two species of Keratodegnathus PACE, 2014 were known, both of them described from Sabah, Borneo, K. rougemonti PACE, 2014 (type species) and K. mirabilis PACE, 2014 . While K. mirabilis is of completely different external morphology (e.g., with short antennae with strongly transverse antennomeres V–X) suggesting that it belongs to Orphnebius , K. rougemonti resembles K. cornutus in many ways (habitus, coloration of a antennae, shape of median lobe of aedeagus). The new species is distinguished from K. rougemonti by completely different coloration ( K. rougemonti : forebody reddish; legs yellow) and apparently also by the shape of the spermatheca. Note, however, that the spermatheca figured by PACE (2014) is clearly incomplete.

Distribution and natural history: The type locality is situated in Cameron Highlands (Peninsular Malaysia: Pahang). The specimens were collected with a flight interception trap at an altitude of 1500–1600 m.