Belonuchus nigerrimus Bernhauer, 1918

Márquez, Juan & Asiain, Julieta, 2022, Taxonomy of the Mexican species of Belonuchus Nordmann (Coleoptera: Staphylinidae), Zootaxa 5152 (1), pp. 1-129 : 80-81

Belonuchus nigerrimus Bernhauer, 1918

Figs. 8b , 10f , 16e , 20f , 24j , 34

Belonuchus nigerrimus Bernhauer, 1918: 225 .

Total body length 13.3 mm. Coloration dark-brown, almost black, with elytra slightly darker than remaining body.

Head: transverse, ratio length/width 0.76. Dorsal surface with sulcate longitudinal midline less visible behind front and more visible at front, latter with a foveate area that extends laterad ( Fig. 10f ). Eyes nearly 0.5 times the cephalic lateral length, weakly protruding laterally. First antennomere almost as long as antennomeres 2–3 combined, 2 slightly shorter than 3, 4–5 slightly longer than wide, 6–10 almost as long as wide. Mandibles 1.4 times longer than head; each mandible with basal tooth and middle tooth widely separated from each other; mandibular channel well developed, external margin visible and internal margin strongly carinate at base, reaching level of middle tooth, then becoming less visible like impressed line. Apical palpomere of maxillary and labial palpi almost twice as long as preapical palpomere. Head 1.13 times wider than pronotum. Neck with wrinkled microsculpture ventrally.

Thorax: dorsal rows of pronotum with six punctures, with posterior punctures more separated from previous punctures; ratio length/width 1.02; almost as wide at anterior corners as at posterior corners (ratio 1.05). Elytra and scutellum with moderately dense fine setae. Prosternum with elevated transverse area near anterior margin, delimited backwards by a clearly visible transverse line. Intercoxal process of mesoventrite shield-shaped, moderately acute and weakly projecting posteriad; transverse discal ridge broadly U-shaped, not meeting margin of intercoxal process laterally. Profemur with external row of spines initiating near base, extending near level of the few apical spines of internal margin, then interrupted as if two or three spines were lacking, ending in two apical spines; spines black, thick and moderately large. Metacoxa with coarse spines moderately dense; metatrochanter with spines as on coxa, but denser; metafemur without row of spines, but with some coarse setae. Tarsomeres flattened dorsally.

Abdomen: first three visible tergites with posterior basal transverse carina well developed; adjacent depressed area narrow but visible, with sparse wide-superficial punctures combined with fine punctures, tergite 4 also with some wide-superficial punctures at base, remaining surface of each tergite covered with moderately dense, fine punctures. Sternites with punctures similar to those of tergites, but at anterior corners with mesh-like microsculpture looking rough in comparison with that of remaining of their surface, where it is smoother. Male pregenital sternite moderately emarginate at posterior margin ( Fig. 16e ). Male genital sternite short (2.14 times longer than wide), very asymmetrical, anterior portion occupying 30% and posterior portion 70% of its length, apical emargination very deep ( Fig. 20f ). Abdominal styli slender.

Aedeagus: length 1.5 mm; elongate in apical half and ovoid in basal half; apex somewhat convex; basal half notably wider than apical half; internal sac visible ( Fig. 24j ).

Variability. There is the following variation in ratios and measurements: ratio length/width of head in males 0.79 (range 0.71–0.85), in females 0.825 (range 0.82–0.84); ratio mandibular length/cephalic length in males 1.13 (range 0.88–1.35), in females 0.98 (range 0.94–1.02); ratio cephalic width/pronotal width in males 1.15 (range 1.07–1.27), in females 1.11 (range 1.09–1.13); ratio length/width of pronotum in males 1.10 (range 1.03–1.15), in females 1.12 (range 1.05–1.16); ratio anterior width/posterior width of pronotum in males 1.09 (range 1.06–1.14), in females 1.07 (range 1.05–1.09). The paralectotype is of paler color than the lectotype, dark-brown, pronotum with dorsal rows with five (left) and six (right) punctures; external row of spines in profemur with spines smaller than in lectotype.

Taxonomic comments. Of the group platypterus only B. nigerrimus and B. juanmorronei are completely black, but B. nigerrimus has a transverse head, mandibles as long or longer than head, eyes almost 0.5 times the cephalic lateral length, and a different genital sternite and aedeagus than in B. juanmorronei , which also has an almost square head, slightly widened backwards, mandibles shorter than head and eyes less than 0.5 times the cephalic lateral length. Other black species, such as B. moroni , belong to different groups, making it easier to distinguish them using group characters. Lectotype of this species is designated here taking into account Article 74.7 of the ICZN and its recommendations, to establish more clearly the identity of this species.

Type material examined (two males): Lectotype (male, FMNH): “ Jalapa, Mexico / gagates Er. Det. Bernh / nigerrimus Bernh. Typus / Chicago NHMus M. Bernhauer Collection / Lectotype Belonuchus nigerrimus Bernhauer, 1918 , Márquez & Asiain des. 2022” . Paralectotype: “Jalapa, Mexiko. Dabberl/ nigerrimus, Brnh. Cotypus / Chicago NHMus M. Bernhauer Collection” (m 1, FMNH) . Additional material examined (11 males, five females): Mexico: Hidalgo: “La Misión, camino al río Moctezuma, N21°8’30.6”, W99°5’49.1”, bosque tropical subcaducifolio, en NTP-80 (calamar), 23-VI a 5-VII-2017, J. Márquez y A. Lora cols.” (1, CC-UAEH). “Tenango de Doria, camino a La Viejita, bosque mesófilo de montaña, 1647 m, N20°19.0’ 37.9”, W98°14.0’ 39.7”, trampa de intercepción de vuelo #3, 5 a 10-V-2013, N. Gutiérrez col.” (1, CC-UAEH). “ Tianguistengo camino a Santa Mónica , bosque mesófilo de montaña , 1868 m, N20°43’5.4”, W98°39’40.3”, trampa de intercepción de vuelo, 7 al 13-IV-2009, J. Sánchez, M. Rivero, M. Vargas y J. Sánchez cols.” (1, CC-UAEH). “ Tlanchinol, La Cabaña , bosque mesófilo de montaña , 1485 m, N21°1.357’ W98°38.556’, trampa de intercepción de vuelo #5, 18 a 25-III-2006, C. Ortiz y M. C. Pedraza ” (1, CC-UAEH). “ Tlanchinol camino a Apantlazol, El Pozo , bosque mesófilo de montaña , 1391 m, N20°59’6.73”, W98°37’39.86”, NTP-80 (calamar) #2, 22-IV al 10-V-2011, J. Márquez col.” (1, CC-UAEH). Mismos datos excepto: “NTP-80 (calamar) #5” (2, CC-UAEH). Same data, except: “trampa de intercepción de vuelo #2” (1, CC-UAEH). Same data, except: “trampa de intercepción de vuelo #3, 1-X al 22-X-2011, J. Márquez col.” (1, CC-UAEH). Same data, except: “22-IV al 10-V-2011 ” (1, CC-UAEH). “ Zacualtipán , camino a Tizapán , boque mesófilo de montaña , 1690 m, N20°39.076’, W98°36.055’, trampa de intercepción de vuelo #2, 14 al 28-IV-2011, J. Márquez col.” (1, CC-UAEH). Veracruz: “ Córdoba, camino a Plan de Ayala , bosque mesófilo de montaña , 1352 m, N18°57’15.2”, W96°58’41”, NTP-80 (calamar), V a VI-1999, J. Asiain, Q. Santiago, J. Márquez ” (1, MAAS). “ Huatusco, Coxcontla , bosque mesófilo de montaña perturbado , 1250 m, NTP-80 (calamar), 14-I a 11-II-1995, M. A. Pensado y Q. Santiago cols.” (1, QJSJ). Same data, except: “ 29-VII a 26-VIII-1995 ” (1, QJSJ). Same data, except: “ 1 a 29-VII-1995, coprotrampa” (1, QJSJ). Same data, except: “ 6-V a 3-VI-1995, NTP-80 (calamar)” (1, QJSJ). “ Huayacocotla , San Antonio , bosque mesófilo de montaña , 1434 m, N20°40’32.2”, W98°23’26.7”, NTP- 80 (calamar) #3, 6-III a 2-IV-2006, F. Ramírez col.” (1, CC-UAEH). “ Huayacocotla, Helechales , bosque mesófilo de montaña , 1936 m, N20°37.5’ 25” W98°27.6’ 49”, NTP-80 (calamar) #10, 19-III al 2-IV-2011, J. Márquez e I. Martínez cols.” (1, CC-UAEH). “ Totutla, Mata Oscura, Rancho Zacuapam , selva mediana subcaducifolia , 864 m, N19°12’23”, W96°50’32”, hojarasca de riachuelo, 18-V-1999, J. Asiain, Q. Santiago y J. Márquez col.” (1, MAAS) .

Figures

FIGURE 8. Dorsal view of males of: a) Belonuchus aenigmaticus (paratype), b) B. nigerrimus, c) B. optatus, d) B. platypterus, e) B. juanmorronei, f) B. abnormalis, g) B. pectinipes (paralectotype), h) B. viridipennis. Scale bars = 2.5 mm.

FIGURE 10. Dorsal view of the head of males of: a) Belonuchus julietitae, b) B. singularis, c) B. connexus, d) B. platypterus, e) B. bidens, f) B. nigerrimus, g) B. optatus, h) B. cyanipennis, i) B. godmani. Dorsal view of the head and pronotum of the holotype female of: j) B. optatus.

FIGURE 16. Male pregenital sternite of: a) Belonuchus moroni, b) B. dichrous, c) B. flavipennis, d) B. aenigmaticus, e) B. nigerrimus, f) B. juanmorronei, g) B. godmani, h) B. magnistylus, i) B. trochanterinus, j) B. rufipennis, k) B. basiventris, l) B. connexus, m) B. xanthomelas, n) B. ephippiatus, o) B. optatus.

FIGURE 20. Male genital sternite of: a) Belonuchus cifuentesi, b) B. dichrous, c) B. flavipennis, d) B. aenigmaticus, e) B. iridescens, f) B. nigerrimus, g) B. optatus, h) B. platypterus, i) B. juanmorronei, j) B. abnormalis, k) B. pectinipes, l) B. viridipennis, m) Belonuchus sp. Q, n) B. cyanipennis, o) B. godmani. Scale bars = 0.5 mm.

FIGURE 24. Ventral (left) and lateral (right) view (except e) of the aedeagus of: a) Belonuchus rufiventris, b) B. xanthomelas (at center, detail of the apex of the median lobe), c) B. ephippiatus, d) B. moroni, e) B. cifuentesi (left: detail of paramere, right: ventral view; from Rodríguez and Navarrete-Heredia, 2016), f) B. dichrous, g) B. flavipennis, h) B. aenigmaticus, i) B. iridescens, j) B. nigerrimus, k) B. optatus, l) B. platypterus. Scale bar = 0.5 mm (all figures, except e).

FIGURE 34. Geographical distribution in Mexico of Belonuchus nigerrimus.