Belonuchus confusus, Márquez & Asiain, 2022

Márquez, Juan & Asiain, Julieta, 2022, Taxonomy of the Mexican species of Belonuchus Nordmann (Coleoptera: Staphylinidae), Zootaxa 5152 (1), pp. 1-129 : 30-31

Belonuchus confusus sp. nov.

http://zoobank.org/NomenclaturalActs/1cb6c69c-dcd0-4820-a3b6-0753a5bd3c57

Figs. 2f , 14d , 17i, 18e, 21e, 26b

Total body length 11.6 mm. Black on head, pronotum, sixth visible abdominal segment, major part of fifth visible segment (except anterior border), and abdominal styli. Reddish on elytra, legs, sterna, anterior border of fifth visible abdominal segment and visible segments 1–4. Reddish-brown on two apical antennomeres, mandibles, maxillary and labial palpi, scutellum and genital sternite.

Head: transverse, ratio length/width 0.74. Dorsal surface with sulcate longitudinal midline clearly visible in more than anterior half of cephalic length; front moderately foveate at space between antennal insertions. Eyes nearly 0.5 times the cephalic lateral length, slightly protruding laterally. Antennomeres 4–5 elongate, 6–8 almost as long as wide, 9–10 slightly transverse. Mandibles 1.2 times longer than head; each with two well separated teeth (basal and middle), apical area somewhat curved, mandibular channel well developed, external margin well separated from internal margin at base, internal margin extending forward as impressed line beyond level of middle tooth. Maxillary palpi with apical palpomere near 1.25 times longer than preapical palpomere. Labial palpi with apical palpomere 1.1 times longer than preapical palpomere. Head 1.3 times wider than pronotum. Neck with moderate wrinkled microsculpture on ventral surface.

Thorax: left dorsal row of pronotum with five punctures and right dorsal row with six punctures; slightly longer than wide (ratio 1.13) and almost as wide at anterior corners as at posterior corners (ratio 1.03). Scutellum with similar punctures as on elytra, slightly denser. Elytra with fine, moderately dense punctures. Prosternum slightly elevated close to anterior margin. Intercoxal process of mesoventrite acute and V-shaped; transverse discal ridge very fine, slightly acute, interrupted at middle part. Profemur with external row of spines initiating distant from base and ending distant from apex, spines moderately dense, longer spines placed at anterior part, as long as apical spines of internal margin. Metatrochanter modified like a hook, as long as 0.4 times the length of metafemur; metafemur slightly flattened and curved at level of overlap with hook, reaching up to half its length; metatibia weakly curved a little in front of its apical half.

Abdomen: first visible tergite with posterior basal transverse carina clearly visible, moderately visible on tergite 2 and slightly visible on tergite 3; depressed adjacent area with denser punctures than on remaining part of each segment, where punctures are fine and moderately dense. Male pregenital sternite not emarginate at posterior margin, with a tiny medioapical projection (Fig. 17i). Male genital sternite moderately elongate (2.67 times as long as wide), slightly asymmetrical, anterior portion occupying 48% and posterior portion 52% of its length, apical emargination moderately deep but very narrow ( Fig. 18e ). Abdominal styli black, moderately wide and flattened at apex ( Fig. 14d ), with large, dense setae, apex of styli as wide as apical width of metatibiae.

Aedeagus: length 1.6 mm; elongate-convex shape; apex subacute, somewhat rounded; in ventral view, basal half of oval shape and slightly wider than apical half, in lateral view, basal half notably wider than apical half; internal sac visible ( Fig. 21e ).

Variability. An additional male and female were studied. Male with total body length 12.6 mm, ratio length/ width of head 0.65; ratio mandibular length/cephalic length 1.7; ratio length/width of pronotum 1.09; ratio anterior width/posterior width of pronotum 1.1; apical palpomere almost as long as preapical palpomere in maxillary and labial palpi; antennomeres 1–3 black, apical antennomere reddish-brown; head shape transverse, with very long mandibles; elytra with dark punctures; scutellum reddish; pregenital sternite with medial projection of posterior margin indistinguishable. Female with total body length 11.5 mm; ratio length/width of head 0.8; ratio mandibular length/cephalic length 1.0; ratio length/width of pronotum 1.2; ratio anterior width/posterior width of pronotum 1.0; antennomeres 1–3 reddish, remaining antennomeres black; each dorsal row of pronotum with six punctures; scutellum reddish-brown; reddish anterior portion of visible tergite five wider than in male, near 1/4 of their total width.

Taxonomic comment. This species is very similar to B. trochanterinus from Guatemala, but in B. confusus the abdominal styli of males are slightly less widened at apex and more oval-shaped, the pregenital sternite is not emarginate at posterior margin, but with a small medioapical projection, and the genital sternite and aedeagus are different. In B. trochanterinus the abdominal styli of males are widened and not as straight toward apex, male pregenital sternite slightly emarginate at posterior margin, and genital sternite and aedeagus are different. Belonuchus alternans and B. magnistylus also have the abdominal styli of males little to notably widened at apex, but are easily separated from B. confusus because they have more than the last two abdominal segments black, while in B. confusus only the last two abdominal segments are black. There are other species with a coloration pattern similar to B. confusus , such as B. tenuistylus and B. metafemoralis , but they lack the widened male abdominal styli.

Etymology. The name of this species refers to the fact that it can be confused with B. alternans and with B. trochanterinus .

Type material (two males, one female): Holotype (male, FMNH): “ Mexico: Chiapas, 8 mi N Pueblo Nuevo Solistahuacán , 6000’, VIII-26, 27-1973/ white polypore fungus, A. Newton / J. F. Lawrence Lot. No. 3523” . Paratypes: same data as holotype (m 1, f 1, 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 14. Dorsal (left) and ventral (right) view of the first four visible abdominal segments of males of: a) Belonuchus singularis, b) B. tepoztecus. Abdominal styli of male of: c) B. alternans, d) B. confusus, e) B. singularis, f) B. magnistylus (right: detail of left stylus in ventral view), g) B. trochanterinus (right: detail of left stylus in ventral view).

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).