Belonuchus rufiventris ( Sharp, 1887 )

Márquez, Juan & Asiain, Julieta, 2022, Taxonomy of the Mexican species of Belonuchus Nordmann (Coleoptera: Staphylinidae), Zootaxa 5152 (1), pp. 1-129 : 67-68

Belonuchus rufiventris ( Sharp, 1887)

Figs. 6b , 17d, 19m, 24a, 27b

Philonthus rufiventris Sharp, 1887: 787 . Belonuchus rufiventris comb. nov. ex Philonthus ( Chani-Posse et al. 2018b) .

Total body length in males 9.8 mm (both specimens), in females 9.4 and 10.5 mm. Black (sometimes reddish brown) on head, antennomeres 1–9, mandibles, pronotum, scutellum, sterna and coxae. Reddish on apical and preapical antennomeres, maxillary and labial palpi, legs (excluding their coxae), elytra and entire abdomen.

Head: dorsally slightly convex, with rounded posterior corners and quadrate shape toward front; ratio length/ width in males 0.84 and 0.85, in females 0.92 and 0.96. Dorsal surface with sulcate longitudinal midline slightly visible only at front; front weakly foveate. Eyes slightly longer than 0.5 times the cephalic lateral length, weakly protruding at sides. First antenommere as long as antennomeres 2–3 combined, antennomeres 2–3 of almost same length, 4–5 slightly longer than wide, 6 as long as wide, 7–10 transverse. Mandibles as long as head (ratio in males 1.00 and 1.03, in females 0.69, in the second female the mandibles are closed); mandibles in males moderately expanded at base, with a basal tooth and smaller middle tooth that are well separated; mandibular channel with external margin carinate and internal margin like carinate line strongly developed until level of middle tooth, then it fades toward apex. Apical palpomere of maxillary and labial palpi near 1.25 times longer than preapical palpomere. Ratio cephalic width/pronotal width in males 1.18 and 1.22, in females 1.04 and 1.25. Neck with wrinkled microsculpture ventrally.

Thorax: pronotum with microsculpture like wavy lines moderately visible; ratio length/width of pronotum in males 1.11 and 1.15, in females 1.10 and 1.23; ratio anterior width/posterior width of pronotum in males 1.08 (both specimens), in females 1.04 and 1.11; dorsal rows each with only two punctures, with anterior punctures placed at anterior margin and posterior puncture placed at level of lateral macroseta. Elytra and scutellum with fine, moderately dense punctation, covered with pale setae. Prosternum with area near to anterior margin slightly elevated. Intercoxal process of mesoventrite V-shaped; transverse discal ridge well defined, broadly U-shaped or V-shaped, not meeting margin of intercoxal process laterally. Profemur somewhat flattened, in basal 3/4 of its length with only external margin with row of spines, in apical quarter is separated in external and internal margins; spines on external margin numerous and reddish and only some apical spines at internal margin. Posterior legs without modifications in both sexes. Legs generally very long in respect to body and with few spines on tibiae. Femora of all legs more flattened than in majority of species. Tarsomeres weakly flattened dorsally, very long, tarsomeres of posterior legs longer than posterior tibiae.

Abdomen: first three visible tergites with posterior basal transverse carina moderately developed; without depressed adjacent zone, punctures very similar in shape (fine) and density (moderate) over entire surface of each tergite. Abdominal sternites with similar setae as on tergites. Male pregenital sternite deeply emarginate at posterior margin (Fig. 17d). Male genital sternite moderately elongate (2.77 times longer than wide), moderately asymmetrical, anterior portion occupying 36% and posterior portion 64% of its length, apical emargination deep ( Fig. 19m ). Abdominal styli slender.

Aedeagus: length 1.3 mm; cone shaped, with a faint constriction near base; sides converging in almost straight line to form the acute apex; basal half notably wider than apical half, mainly in lateral view; internal sac slightly visible ( Fig. 24a ).

Variability. In addition to the variation in the measurements and ratios indicated in the description, one female has slightly darker coxae, its mandibles are shorter than the head, and the shape of head is more oval. Part of the sulcate longitudinal midline of head is faintly seen on the front of the second female.

Taxonomic comments. Its greatest similarity is with B. longitarsus (see taxonomic comments of that species). The female holotype of this species was not studied, but we analyzed some photos of this specimen (NHM, shared by M. Chani Posse, also a photo included in the work of Chani-Posse et al. 2018b), which together with the information of the original description ( Sharp 1887) allowed us to identify this species. It is possible that the type locality of this species, “Amecameca in Morelos ” ( Sharp 1887: 787) could be placed in the Estado de México, like in one of the studied specimens.

Material examined (two males, two females): Mexico: Estado de México: “ Amecameca , 16-IX-1964, ex nest of / Cratogeomys merriami merriami, G. Halffter & E. G. Matthews, Field Museum” (m 2, f 1, FMNH) . Morelos: “ Mexicapa , bosque de pino, zona 3, NTP-80 (calamar), 14-VIII-1993, A. Soria, C. Cabello y E. Córdoba cols.” (f 1, MAAS) .

Figures

FIGURE 6. Dorsal view of males (except figure c) of: a) Belonuchus longitarsus (holotype), b) B. rufiventris, c) B. iteratus (male lectotype and female paralectotype, NHM©), d) B. xanthomelas (NHM©, Biologia Centrali-Americana), e) B. xanthomelas, f) B. ephippiatus, g) B. moroni (paratype). Scale bars = 2.5 mm.

FIGURE 19. Male genital sternite of: a) Belonuchus tepoztecus, b) B. trochanterinus, c) B. zunilensis, d) B. bidens, e) B. erichsoni, f) B. jalappensis, g) B. mixtecus, h) B. pollens, i) B. rufipennis, j) B. basiventris, k) B. connexus, l) B. longitarsus, m) B. rufiventris, n) B. xanthomelas, o) B. ephippiatus, p) B. moroni. 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).