Belonuchus cariniventris Bernhauer, 1918

Márquez, Juan & Asiain, Julieta, 2022, Taxonomy of the Mexican species of Belonuchus Nordmann (Coleoptera: Staphylinidae), Zootaxa 5152 (1), pp. 1-129 : 26-27

Belonuchus cariniventris Bernhauer, 1918

Figs. 2d , 11a , 17f, 18c, 21c, 26b

Belonuchus cariniventris Bernhauer, 1918: 225

Total body length 10.6 mm. Color reddish-brown, glossy, head with iridiscent shine, elytra darker than remaining body (almost black).

Head: transverse; ratio length/width 0.83. Dorsal surface shiny; sulcate longitudinal midline visible only in anterior half of head. Eyes somewhat protruding, occupying almost 0.5 times the cephalic lateral length, in dorsal view widely separated. First antennomere as long as 2–3 combined, antennomeres 2–3 almost equal in length, 4–5 as long as wide, 6–10 transverse. Ratio mandibular length/cephalic length 0.93; right mandible with one middle dorsal tooth and one acute ventral tooth closer to dorsal tooth; left mandible only with one bilobed middle dorsal tooth; mandibular channel well developed, with carinate external and internal margins. Apical palpomere of maxillary and labial palpi almost twice the length of preapical palpomere. Ventral surface with seven to eight punctures at each middle part distributed toward sides. Ratio cephalic width/pronotal width 1.28. Neck with wrinkled microsculpture ventrally.

Thorax: pronotum with five punctures in each dorsal row; slightly longer than wide (ratio 1.14) and wider at anterior corner than at posterior corner (ratio 1.21). Elytra and scutellum with fine setae moderately dense. Prosternum with a tranverse elevated zone behind anterior margin. Intercoxal process of mesoventrite shield-shaped, with a fine mid longitudinal carina initiating at anterior margin and extending until middle part of area between intercoxal process and transverse discal ridge latter V-shaped, not meeting margin of intercoxal process laterally ( Fig. 11a ). External row of profemur with few and small spines (seven to eight), which are separated from apex; internal margin with three to four apical spines. Posterior legs with trochanter modified like hook, as long as, or slightly longer than 1/3 of the length of posterior femur, hook elongate and curved only at apex; posterior femur curved at level of overlap with hook, right femur with three spines and left femur with four spines of moderate size, placed at ventral internal margin, at hook level, forward of basal half; posterior tibia curved in apical third. Tarsomeres slender, slightly flattened dorsally.

Abdomen: first three visible tergites with posterior basal transverse carina slightly developed; adjacent depressed area well developed, with wide-superficial punctures that disappear towards posterior half of each tergite, where there are fine punctures. First visible tergite with a small median longitudinal ridge that extends from anterior margin to half its length; visible tergites 2–3 with a similar ridge, but shorter and less developed than ridge on first tergite; remaining tergites only with fine setae. Sternites with moderately dense fine setae; first three visible sternites with some wide-superficial punctures in their basal half. Male pregenital sternite with deep V-shaped emargination at posterior margin (Fig. 17f). Genital sternite very long (3.5 times as long as wide), slightly symmetrical, with anterior margin almost flattened, anterior portion occupying 8% and posterior portion 92% of its length, apical emargination deep ( Fig. 18c ). Abdominal styli slender at apex.

Aedeagus: length 0.94 mm; elongate-pointed shape; apical 2/3 very slender in comparison with basal third, which is slightly wider and rounded; internal sac not visible ( Fig. 21c ).

Variability. In the two male paralectotypes, the measurements and ratios are: total length 9.0 and 10.1 mm, ratio length/width of head 0.86 and 0.91, ratio mandibular length/cephalic length 1.03 (in some specimens the mandibles could not be opened); ratio cephalic width/pronotal width 1.27 and 1.29; ratio length/width of pronotum 1.18 and 1.19; ratio anterior width/posterior width of pronotum 1.12 and 1.18. Each half of cephalic ventral surface with 6–7 setiferous punctures. Elytra and scutellum paler than in lectotype, almost the same tone than in the remaining body. Profemora with external row of spines more developed, row continuous almost from the base until 3/4 of their length. Femora of posterior legs with 1–5 spines at their internal margin. Ridge of tergites 2–3 from slightly developed to unconspicuous, but clearly visible in the first tergite.

Taxonomic comments. No species in the trochanterinus group has a color similar to that of B. cariniventris , nor do they have several punctures on the ventral surface of the head, nor the carina in the middle apical part of the mesoventrite, nor the small median ridges of the first three visible abdominal tergites. From the rest of the species groups, it is easily distinguished by having the posterior trochanter of the males modified like a hook. The presence of this last character is what supports its placement in this group of species, but its almost all black or reddish-brown body color, the teeth of the right mandible (one half-ventral and the other half-dorsal) and its relatively small size, are characteristics that make it similar to some species of the viridipennis group and cast doubt on its correct assignment to this group of species. It should be tested in the future with a more comprehensive analysis. Another aspect to attract attention to is related to the absence of specimens other than the type series in the different collections studied despite the fact collecting has been carried out in Xalapa and its surroundings. It was decided to designate a lectotype of this species taking into account Article 74.7 of the International Code of Zoological Nomenclature (ICZN 1999) and its recommendations, in order to establish, in the best possible way, the identity of this species.

Type material examined (three specimens): Lectotype (male, FMNH) : “ Jalapa , Mexico, F. Schneider / 39 / cariniventris Bernhauer , Typus / Chicago NHMus M. Bernhauer Collection / Lectotype Belonuchus cariniventris Bernhauer, 1918 , Márquez & Asiain des. 2022” . Paralectotypes: “ Jalappa , Mexiko, Dallerl / cariniventris Bernh. Cotypus / Chicago NHMus M. Bernhauer Collection ” (1 male, FMNH) . Same data as lectotype, except “Cotypus” (1 male, FMNH) .

Figures

FIGURE 2. Dorsal view of males of: a) Belonuchus alternans (syntype, NHM©), b) B. alternans, c) B. apiciventris, d) B. cariniventris (lectotype), e) B. colon, f) B. confusus (holotype), g) B. julietitae (paratype), h) B. linuzensis (paratype). Scale bars = 2.5 mm.

FIGURE 11. Mesoventrite of males of: a) Belonuchus cariniventris, b) B. oxyporinus, c) B. rufisternus, d) B. tepoztecus, e) B. bidens, f) B. jalappensis, g) B. longitarsus, h) B. ephippiatus, i) B. dichrous, j) B. flavipennis, k) B. platypterus, l) B. juanmorronei, m) B. iridescens. Red arrow: intercoxal process of the mesoventrite, blue arrow: transverse discal ridge, green arrow: longitudinal carina in anterior half.

FIGURE 18. Male genital sternite of: a) Belonuchus altenans, b) B. apiciventris, c) B. cariniventris, d) B. colon, e) B. confusus, f) B. julietitae, g) B. magnistylus, h) B. linuzensis, i) B. metafemoralis, j) B. oxyporimimus, k) B. oxyporinus, l) B. pulcher, m) B. rufisternus, n) B. singularis, o) B. tenuistylus. Scale bars = 0.5 mm.

FIGURE 21. Ventral (left) and lateral (right) view of the aedeagus of: a) Belonuchus alternans, b) B. apiciventris, c) B. cariniventris, d) B. colon, e) B. confusus, f) B. julietitae, g) B. linuzensis, h) B. magnistylus, i) B. metafemoralis. Scale bar = 0.5 mm (all figures).