Belonuchus pectinipes Bernhauer, 1910

Márquez, Juan & Asiain, Julieta, 2022, Taxonomy of the Mexican species of Belonuchus Nordmann (Coleoptera: Staphylinidae), Zootaxa 5152 (1), pp. 1-129 : 86-87

Belonuchus pectinipes Bernhauer, 1910

Figs. 8g , 17b, 20k, 25c, 32a

Belonuchus pectinipes Bernhauer, 1910: 379 .

Total body length 10.3 mm. Coloration almost completely black, except elytra, legs, and last two visible abdominal segments that are reddish-brown; the elytra are particularly very glossy (like varnished wood). Abdominal styli reddish.

Head: oval shape, posterior corners convex; ratio length/width 0.84. Dorsal surface with sulcate longitudinal midline weakly visible only at front; front moderately foveate between antennal insertions. Eyes slightly less than 0.5 times the cephalic lateral length, slightly protruding laterally. First antennomere as long as antennomeres 2–3 combined, 2 slightly shorter than 3, 4 elongate, 5 as long as wide, 6–10 transverse. Mandibles 1.09 times as long as head; right mandible with three middle teeth very close to each other, with ventral tooth the biggest; left mandible with two middle teeth in dorsal position very close to each other; both mandibles with a small basal tooth; mandibular channel with external and internal margins well developed. Apical palpomere of maxillary and labial palpi almost twice as long as preapical palpomere. Head 1.16 times wider than pronotum. Neck with wrinkled microsculpture in ventral view.

Thorax: pronotum with left dorsal row with five punctures and right dorsal row with six punctures; pronotum slightly longer than wide (ratio 1.15) and somewhat wider at anterior corners than at posterior corners (ratio 1.13). Elytra and scutellum glossy, with sparse, fine setae and smooth spaces. Prosternum slightly elevated close to anteri- or margin. Intercoxal process of mesoventrite elongate scutellum-shaped; transverse discal ridge broadly U-shaped, not meeting margin of intercoxal process laterally. Profemur with row of spines at external margin, from its base to 3/4 of its length, spines increasing in size from base to apex, where they are very conspicuous (as long as, or longer than last tarsomere of anterior legs); apical spines of internal margin smaller than apical spines of external margin. Posterior legs with long, black spines on coxae and trochanters without regular order; femora and tibiae without modifications. Tarsomeres moderately flattened dorsally.

Abdomen: first three visible tergites with posterior basal transverse carina well developed; adjacent area moderately depressed and narrow, with some wide-superficial punctures combined with fine punctures, outside of these depressions and on remaining tergites only with fine punctures. Sternites with punctures and setae as on tergites. Male pregenital sternite moderately emarginate at posterior margin (Fig. 17b). Male genital sternite very elongate (3.1 times longer than wide), moderately symmetrical, anterior portion occupying 23% and posterior portion 77% of its length, apical emargination moderately deep ( Fig. 20k ). Abdominal styli slender.

Aedeagus: length 1.15 mm; very elongate and slender; apex rounded; basal portion slightly wider than apical portion (best seen in lateral view), apical portion nearly 2/3 of aedeagus length; internal sac visible ( Fig. 25c ).

Variability. The second male specimen of the type series has an iridescent sheen and is dorsally flatter than the lectotype; longitudinal midline of head inconspicuous in anterior half, in addition to foveate area on front; tarsomeres slightly flattened in dorsal view; elytra and particularly on abdomen with long to very long setae; areas adjacent to posterior basal transverse carina of first three visible abdominal tergites slightly depressed and almost smooth. Total body length 8.6 mm (althougth measured with last two abdominal segments not fully extended); ratio length/width of head 0.84; ratio mandibular length/cephalic length 1.07; ratio cephalic width/pronotal width 1.23; ratio length/width of pronotum 1.19; ratio anterior width/posterior width of pronotum 1.13. Females (two specimes of type series) with head flattened rather than convex; right mandible with middle two teeth of small size; dorsal rows of pronotum with five punctures (both rows); profemora with fewer spines at external margin, but two to three apical spines as long as last tarsomere of anterior legs. Total body length 10.3 and 8.9 mm respectively; ratio length/ width of head 0.95 and 1.00; ratio mandibular length/cephalic length 0.75 and 0.87; ratio cephalic width/pronotal width 1.04 (both); ratio length/width of pronotum 1.22 and 1.29; ratio anterior width/posterior width of pronotum 1.04 and 1.09.

Taxonomic comments. This species is similar to B. viridipennis in size and color pattern. It can be distinguished because B. pectinipes is more reddish brown, its head is oval, the left mandible has a basal tooth and two middle teeth, the right mandible has a basal tooth and three middle teeth, pronotum slightly wider at anterior corners than at posterior corners (ratio 1.13 times), the femora of posterior legs are without spines, the coxae and trochanters of posterior legs of males are with long black spines, and its aedeagus is very elongate and slender, with apex rounded ( Fig. 25c ). In contrast, B. viridipennis has a subquadrate head, left mandible with only one middle tooth of peculiar shape ( Fig. 9g ), right mandible with two teeth, ventral tooth longer than dorsal tooth, pronotum wider at anterior corners than at posterior corners (ratio 1.23–1.53), femora of posterior legs of both sexes with two rows of spines, coxae and trochanters of posterior legs of males without spines, and aedeagus with elongate shape at anterior 2/3, and oval shape at basal third, with pointed apex ( Fig. 25d ). As was commented under B. cariniventris , it is remarkable that only the type specimens of B. pectinipes are known, since Córdoba is a site in Veracruz where collections have been made for a long time and until relatively recently. Lectotype of this species is designated here in order to clearly establish the identity of this species.

Type material examined (two males, two females): Lectotype (male, FMNH) : “Cordoba, Mex. Ver. Dr. A. Fenyes / pectinipes Brnh. Cotypus / Chicago NHColl. M. Bernhauer Collection / Lectotype Belonuchus pectinipes Bernhauer, 1910 , Márquez & Asiain des. 2022”. Paralectotypes: same data as lectotype, except: “Typus” (m 1, FMNH) ; same data as lectotype (f 2, FMNH) .

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 9. Dorsal view of males of: a) Belonuchus sp. Q, b) B. cyanipennis (holotype), c) B. godmani. Head of B. dichrous showing the temporal carina (red arrow): d) lateral view (male), e) dorsal view (male). Dorsal view of the mandibles of males of: f) B. platypterus, g) B. viridipennis. Mandibles of Belonuchus sp. Q (male): h) dorsal view, i) ventral view. Antennae of males of: j) B. godmani, k) B. cyanipennis. Scale bars = 2.5 mm.

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 25. Ventral (left) and lateral (right) view of the aedeagus of: a) Belonuchus juanmorronei, b) B. abnormalis, c) B. pectinipes, d) B. viridipennis, e) Belonuchus sp. Q, f) B. cyanipennis, g) B. godmani. Scale bar = 0.5 mm (all figures).