Orphnebius extensus, Assing, 2016

Assing, Volker, 2016, On some Lomechusini of the Palaearctic and Oriental regions (Coleoptera: Staphylinidae: Aleocharinae), Beiträge Zur Entomologie = Contributions to Entomology 66 (1), pp. 13-111 : 52-53

publication ID

https://doi.org/ 10.21248/contrib.entomol.66.1.13-111



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scientific name

Orphnebius extensus

sp. nov.

Orphnebius extensus View in CoL spec. nov.

( Figs 6 View Figs 1–26 , 31 View Figs 27–39 , 233–235 View Figs 216–235 )

Type material: Holotype ♂: “ Laos, 1.–16.v.1999, Louangphrabang pr. , 20°33–4'N 102°14'E, Ban Song Cha (5 km W), 1200 m, Vít Kubáň leg. / Holotypus ♂ Orphnebius extensus sp. n., det. V. Assing 2015” ( NHMB) .

Paratypes: 10 exs.: same data as holotype ( NHMB, cAss) ; 11 exs.: “ Laos-N ( Louangphrabang ), 11–21.v.2002, 19°35'N, 101°58'E, Thong Khan , ~ 750 m, Vít Kubáň leg.” ( NHMB, cAss) GoogleMaps ; 3 exs.: “ Laos-N ( Oudomxai ), 1–9.v.2002, ~ 1100 m, 20°45'N 102°09'E, Oudom Xai (17 km NEE), Vít Kubáň leg.” ( NHMB, cAss) GoogleMaps .

Etymology: The specific epithet (Latin, adjective: stretched) alludes to the long and slender parameres (especially the condylite) and median lobe of the aedeagus.

Description: Body size very variable; body length 3.2–4.3 mm; length of forebody 1.4–1.7 mm. Coloration: forebody black, with the elytra sometimes slightly paler anteriorly and in postero-median portion; abdomen red; legs with dark-brown femora and with reddish tibiae and tarsi; antennae blackish with antennomeres II–IV at least partly dark-reddish; maxillary palpi brown to darkbrown with the apical palpomere yellowish.

Head ( Fig. 31 View Figs 27–39 ) conspicuously wedge-shaped, broadest posteriorly, 1.56–1.88 times as broad as long, larger and more transverse in larger than in smaller specimens; posterior margin convex (small specimens) to truncate (large specimens); clypeus with broad and truncate anterior margin, near anterior margin with more or less pronounced elevation or tubercle (more pronounced in larger than in smaller specimens); dorsal surface nearly impunctate. Eyes strongly convex and asymmetrically wedge-shaped, situated in posterior angles of head (i.e., posterior margin of eye forming posterior margin of head postero-laterally). Antenna ( Fig. 6 View Figs 1–26 ) 1.0– 1.4 mm long; antennomere I conspicuously elongate, approximately as long as combined length of antennomeres II–IV; antennomeres III–IV distinctly, V–X weakly flattened; IV–X transverse; V much larger and more transverse (approximately 1.5 times as broad as long) than IV; V–X asymmetric, of gradually increasing width, and distinctly transverse, VII–X nearly twice as broad as long; XI nearly as long as combined length of VIII–X.

Pronotum ( Fig. 31 View Figs 27–39 ) approximately 1.5 times as broad as long and 0.75–0.88 times as broad as head, smaller and narrower in relation to head in larger than in smaller specimens, moderately convex in cross-section; lateral and posterior margins together nearly forming a semicircle, posterior angles completely obsolete; disc with a median pair of punctures and sometimes few scattered additional punctures; lateral margins anteriorly with three long, erect, stout black setae.

Elytra ( Fig. 31 View Figs 27–39 ) 0.80–0.85 times as long as pronotum; punctation sparse and extremely fine; pubescence long, fine, and sub-erect. Hind wings fully developed. Metatarsomere I approximately as long as the combined length of II and III.

Abdomen: tergites III–VI with a lateral setiferous puncture on either side, VI with four additional punctures at posterior margin; tergite VII with dense longitudinal striae and oblong non-setiferous punctures in posterior two-thirds or three-fourths, near posterior margin with small and strongly oblong setiferous tubercles, posterior margin with palisade fringe; tergite VIII with two transverse series of long black setae posteriorly, posterior margin convex; sternite VIII with broadly convex posterior margin.

♂: segments IX–X distinctly modified (of the O. hauseri type), with dense and long pubescence; median lobe of aedeagus ( Figs 233–234 View Figs 216–235 ) 0.80–0.95 mm long, very slender; ventral process long and slender, apically shaped like a spear-head in ventral view; paramere ( Fig. 235 View Figs 216–235 ) 0.65–0.70 mm long, with slender paramerite and with conspicuously narrow (in apical half nearly filiform) condylite.

♀: segments IX–X distinctly modified (modifications of the O. hauseri type), with dense and long pubescence; spermathecal capsule with long and coiled proximal portion.

Intraspecific variation: This species is subject to pronounced intraspecific variation of body size. Other variable characters (head shape and relative size, median tubercle on labrum, length of antennae, etc.) are related to body size, i.e., large specimens have a relatively larger and posteriorly more truncate head, a more pronounced median tubercle on the labrum, and longer antennae.

Comparative notes: As can be inferred from the similar external and sexual characters, particularly the derived morphology of the head and pronotum, the similar segments VII–X of the abdomen, and the derived morphology of the parameres, O. extensus is closely related to O. dilatatus , from which it differs by wedge-shaped and more bulging eyes in more posterior position, the shape of the labrum (with median tubercle and truncate anterior margin), the shape of the antennae (antennomeres V–X more transverse and more distinctly asymmetric), reddish tibiae, the convex posterior margin of the abdominal tergite VIII, and by the primary sexual characters. According to their respective original descriptions, the species with a similar head shape described from Thailand ( O. semivorax , O. incertus ) do not have wedge-shaped eyes.

Distribution and natural history: The specimens were collected in three localities in Louangphrabang and Oudomxai provinces, North Laos, partly together with O. dilatatus , O. lunatus , O. nigrapicali s, O. reductus , O. serratus , O. latitibalis , O. bicuspis , O. retunsus , O. cultellatus , O. carinatus , O. integer , and/or O. septemcuspis . The altitudes range from 750 to 1200 m.


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