Belonuchus metafemoralis, Márquez & Asiain, 2022

Márquez, Juan & Asiain, Julieta, 2022, Taxonomy of the Mexican species of Belonuchus Nordmann (Coleoptera: Staphylinidae), Zootaxa 5152 (1), pp. 1-129 : 36-37

publication ID

publication LSID


persistent identifier

treatment provided by


scientific name

Belonuchus metafemoralis

sp. nov.

Belonuchus metafemoralis sp. nov.

Figs. 3b View FIGURE 3 , 12m View FIGURE 12 , 15j View FIGURE 15 , 18i View FIGURE 18 , 21i View FIGURE 21 , 27b View FIGURE 27

Total body length 11.4 mm. Black on head, antennae, pronotum, posterior 3/4 of fifth visible abdominal segment and all sixth, prosternum, anterior half of mesoventrite and abdominal styli. Reddish on elytra, legs, posterior half of mesoventrite, metaventrite, first four visible abdominal segments and anterior 1/4 of fifth visible segment. Mandibles, maxillary and labial palpi, and genital segment brown.

Head: transverse, slightly convex at posterior corners and on vertex; ratio length/width 0.74. Dorsal surface with indistinctly visible microsculpture of waved lines; sulcate longitudinal midline visible in anterior half of head; front with a narrow area clearly foveate near anterior margin. Eyes nearly 0.5 times the cephalic lateral length, not protruding at sides. Antennomere 4 slightly elongate, 5 almost as long as wide, 6–10 transverse. Mandibles 1.41 times longer than head; with two well separated teeth, basal tooth longer than middle tooth; mandibular channel with external margin widely separated from internal margin at base, internal margin carinate, extending forward slightly beyond level of middle tooth. Apical palpomere of maxillary and labial palpi nearly 1.25 times longer than preapical palpomere. Head 1.25 times wider than pronotum. Neck with wrinkled microsculpture ventrally.

Thorax: each dorsal row of pronotum with four punctures; pronotum slightly longer than wide (ratio 1.13), almost as wide at anterior corners as at posterior corners (ratio 1.03). Scutellum and elytra with fine, sparse punctures and setae. Prosternum with area close to anterior margin slightly elevated, with microsculpture as on neck. Anterior half of mesoventrite with microsculpture as on neck; intercoxal process shield-shaped, lateral margin well developed; transverse discal ridge broadly U-shaped, laterally meeting with lateral margin of intercoxal process. Profemur with external row of spines initiating in basal fourth and reaching apex, but interrupted before apex, as if one or two spines were missing; spines increasing in size toward apex; internal margin developed only near apex, where bearing few spines. Metatrochanter modified like a hook, wide in basal 2/3 and slender and straight in distal third, ending in an angle of 90°, hook as long as 1/3 of length of metafemur ( Fig. 12m View FIGURE 12 ); metafemur with a convex carina near base of its ventral surface, delimiting a slight to moderate cavity to accommodate the hook. Metatibia weakly curved at internal margin near apex. Tarsomeres slightly flattened dorsally.

Abdomen: first three visible tergites with posterior basal transverse carina well developed, adjacent area slightly depressed, narrow and with sparse wide-superficial punctures; remaining surface of tergites 1–3 and remaining tergites with fine, sparse punctures and setae. Anterior half of visible sternites 1–4 with wide-superficial punctures denser than on tergites 1–3, remaining surface only with fine, sparse punctures and setae. Male pregenital sternite with slight, broadly arcuate emargination ( Fig. 15j View FIGURE 15 ). Male genital sternite short (2.0 times longer than wide), slightly asymmetrical, anterior portion occupying 30% and posterior portion 70% of its length, apical emargination deep ( Fig. 18i View FIGURE 18 ). Abdominal styli slender.

Aedeagus: length 1.3 mm; elongate shape, with a constriction in apical third; apex slightly rounded in ventral view and slightly acute in lateral view; in lateral view, basal half wider than apical half; internal sac visible ( Fig. 21i View FIGURE 21 ).

Variability. Measurements and ratios (males n=3, females n=3): total body length in males 10.9 mm (range 10.5–11.5 mm), in females 10.7 (range 10.3–11.3 mm); ratio length/width of head in males 0.78 (range 0.76–0.80), in females 0.91 (range 0.90–0.93); ratio mandibular length/cephalic length in males 1.23 (range 1.04–1.37), in females 0.89 (range 0.81–1.00); ratio cephalic width/pronotal width in males 1.15 (range 1.13–1.19), in females 1.04 (range 1.02–1.06); ratio length/width of pronotum in males 1.11 (range 1.10–1.13) in females 1.14 (range 1.10–1.18); ratio anterior width/posterior with of pronotum in males 1.01 (range 1.00–1.03), in females 1.0 (without variation). In addition, there is a variation in the sulcate longitudinal midline of the head that can go further back than the eye level; dorsal rows of punctures in the pronotum are predominantly 5:5, but 6:6 and 4:5 also occur; in a female and a male the wide-superficial punctures of the abdomen appear denser; in one female the elytra and legs are reddish-dark, and the abdomen is shiny brown.

Taxonomic comments. This species is very similar to B. tenuistylus , from which it differs in the fifth visible abdominal segment black in basal 3/4 and reddish in anterior 1/4, the metafemur of males has a cavity delimited by a carina where each hook is possibly accommodated, and in the particular shape of aedeagus and genital sternite; while B. tenuistylus has the basal half of the fifth visible abdominal segment black and the apical half reddish, the metafemur of males lacks the cavity and carina, and they have a different aedeagus and genital sternite.

Etymology. The name of this species refers to the femur of the male posterior legs, with a cavity delimited by a carina, a structure that has not been observed in any other species.

Type material (seven males, five females): Holotype (male, CC-UAEH) : “ México: Hidalgo, Zimapán, Parque Nacional Los Mármoles, Minas Viejas , bosque de encino, 1892 m, N20°55’5.2”, W99°12’ 41.1”, NTP-80 (calamar), 11-X al 17-XI-2007, J. Márquez, J. Asiain y S. Sierra cols.” GoogleMaps . Paratypes: Mexico: Chihuahua: “ Urique, Cerocahui , El Salitre, 1700 m, trampa de intercepción de vuelo, 9 a 12-VII-2006, M. Castillo y L. Delgado cols.” (m 1, IEXA) . Same data, except: “El Dique, 1780 m, 18 a 21-VII-2006 ” (f 3, IEXA) . Hidalgo “ Cardonal , El Boxo, bosque de encino, trampa de intercepción de vuelo, 20 a 27-VII-2019, Y. Buena col.” (m 1, CC-UAEH) . “ Huasca, ex Hacienda El Paraíso , localidad 2, bosque Juniperus - Quercus , trampa de intercepción de vuelo, 16 a 22-VI-2010, J. Asiain y J. Márquez cols. “ (1, CC-UAEH) . “ Jacala de Ledezma, P. N. Los Mármoles, camino a Plomosas , bosque de pino-encino, 1811 m, N20°56’33.9”, W99°12’25.6”, en tronco con hongos, 20-X-2006, J, Márquez y J. Asiain cols.” (1, CC-UAEH) GoogleMaps . Santiago de Anaya , El Encinal, N20°26’56.0”, W98°55’20.5”, matorral xerófilo y encinos, trampa cebada con nopales fermentados, 22 a 29-VII-2018, F.M. Gómez I.S. Hernández cols.” (1, MAAS) GoogleMaps . Same data as holotype (3, CC-UAEH) GoogleMaps .


Natuurhistorisch Museum Maastricht, Botany Department