Belonuchus Nordmann, 1837

Li, Liang & Zhou, Hong-Zhang, 2010, Revision of the Chinese species of the genus Belonuchus Nordmann (Coleoptera: Staphylinidae: Philonthina), Journal of Natural History 44 (35 - 36), pp. 2149-2177 : 2151-2153

Genus Belonuchus Nordmann, 1837

Nordmann 1837: 129 (genus, species included: B. haemorrhoidalis ); Bernhauer and Schubert 1914: 369 (world catalogue, 93 species); Blackwelder 1943: 420 (key to species of West Indies); Shibata 1973: 61 (checklist of species of Taiwan); Shibata 1983: 139 (checklist of species of Japan); Smetana 1995: 32, 722 (key to North American species); Newton et al. 2000: 395 (nine Nearctic species, characters in key); Herman 2001: 2517 (world catalogue); Smetana 2004: 629 (catalogue for Palaearctic region).

Type species

Staphylinus haemorrhoidalis Fabricius, 1801 ; fixed by monotypy.

Synonym

Trapeziderus Motschulsky 1860: 77 (type species: Trapeziderus bicolor Motschulsky , fixed by monotypy); Fauvel 1895: 266 (synonym of Belonuchus ).

Trapezinotus Motschulsky 1870: 49 (type species: Trapezinotus bicolor Motschulsky ); Fauvel 1895: 266 (synonym of Belonuchus ).

Musicoderus Sharp 1885: 455 (type species: Musicoderus cephalotes Sharp ); Blackwelder 1943: 420 (synonym of Belonuchus ).

Diagnosis

The genus Belonuchus may be easily recognized by the combination of the following characters: body usually depressed; maxillary palpi long, with palpomere IV rod-like and distinctly longer than palpomere III ( Figures 4J , 9L ); labial palpi moderately long, with palpomere III slightly longer than palpomere II ( Figures 4C , 9J ); anterior tarsomeres I–IV in both sexes simple, not dilated, lacking modified pale setae ventrally ( Figure 9I ) or more or less dilated, with some modified pale setae ventrally ( Figure 4K ); superior line of pronotal hypomeron bent ventrad at about mid-length of pronotum so that lateral puncture of pronotum, bearing long seta, separated from it by distance at least three times diameter of puncture ( Figures 4E , 9E ); mesoventrite widely separating middle coxae, usually with transverse carina ( Figures 4F , 9F ); abdomen with first three or four visible tergites bearing two basal lines ( Figures 4H , 9G ); basal line of sternite III extended apicad into arcuate process ( Figures 4G , 9H ); sternite VIII of male variably emarginate medio-apically; sternite IX of male with basal portion more or less asymmetrical; paramere of aedeagus with or without sensory peg setae.

Note

Using the conventional and currently accepted concept, the genus Belonuchus is heterogeneous in its morphology. In this study, we carefully examined those species that were available to us, representatives of the Palaearctic, Oriental, Nearctic and Neotropical regions. We found that there are two lineages according to morphological differences in protarsi and genitalia: (1) protarsi in both sexes dilated, with some modified pale setae ventrally and paramere of aedeagus well developed, usually with peg setae on underside of paramere; many Old World species of Belonuchus belong to this lineage. According to Schillhammer (private correspondence), this lineage is not Belonuchus but the genus Trapeziderus Motschulsky, 1860 (at present a synonym of Belonuchus , which should be reinstated in the future); (2) protarsi in both sexes simple, not dilated, lacking modified pale setae ventrally and paramere of aedeagus usually very small, without peg setae on underside of paramere; this lineage represents the true Belonuchus erected by Nordmann (1837). To solve this taxonomic issue, however, a study based on the world fauna is required, to avoid the danger of unnecessary confusion.

Key to Chinese species of the genus Belonuchus Nordmann, 1837

1. Anterior tarsomeres I–IV simple, not dilated, without modified pale setae ventrally..................................................... 2

Anterior tarsomeres I–IV dilated, with modified pale setae ventrally..... 5

2. Frons of head impressed, with dense punctures...................... 3

Frons of head not impressed, without dense punctures................ 4

3. Body small (HPL: 1.96 mm), posterior margin and suture of elytra markedly reddish-brown............................ B. puncticulus Rougemout

Body distinctly larger (HPL: 2.20–2.45 mm), elytra entirely black................................................. B. punctifrons (Cameron)

4. Antennae long, with antennomeres VIII–X slightly transverse...................................................... B. admirabilis sp. nov.

Antennae short, with antennomeres V–X distinctly transverse....................................................... B. applanatus sp. nov.

5. Tempora with a carina extending ventrally from posterior margin of tempora............................................. B. imitator Cameron

Tempora without carina........................................ 6

6. Pronotum entirely reddish-brown................ B. grandiceps (Kraatz)

Pronotum black............................................... 7

7. Scutellum usually reddish-brown, posterior margins of tergites III–VIII markedly reddish-brown.......................... B. coomani sp. nov.

Scutellum black, tergites III–VIII entirely black or sometimes only posterior margins of tergites III–IV narrowly reddish-brown..... B. rufoniger Fauvel

Figures

Figure 4. Scanning electron micrographs of Belonuchus coomani sp. nov. (A) Underside of head, showing gular sutures (arrows), ventral view; (B) mentum, showing one anterolateral seta on each side (arrow); (C) labial palpus; (D) prosternum; (E) pronotal hypomeron; (F) mesoventrite, showing transversal carina (arrow); (G) first visible sternite, showing basal line (arrow); (H) tergites III–V, showing two basal lines (arrows); (I) protergal glands (osmeteria); (J) maxillary palpus and right mandible, ventral view; (K) protarsus with modified pale setae, ventral view; (L) apical portion of last segment of protarsus, empodial setae absent.

Figure 9. Scanning electron micrographs of Belonuchus punctifrons (Cameron, 1926). (A) Underside of head, showing gular sutures (arrows), ventral view; (B) labium; (C) mentum, showing