Belonuchus flavipennis Solsky, 1870

Márquez, Juan & Asiain, Julieta, 2022, Taxonomy of the Mexican species of Belonuchus Nordmann (Coleoptera: Staphylinidae), Zootaxa 5152 (1), pp. 1-129 : 74-75

Belonuchus flavipennis Solsky, 1870

Figs. 7d, e , 11j , 16c , 20c , 24g , 29b

Belonuchus flavipennis Solsky, 1870: 263 .

Total body length 11.2 mm (range 10.4–12.0 mm). Female not studied. Body black, except elytra that are reddish. Apical antennomere, maxillary and labial palpi, and tarsomeres reddish-brown. Sixth visible abdominal segment with anterior 1/4 or slightly more, genital segment and base of abdominal styli yellowish.

Head: subquadrate, sides and posterior corners slightly convex; ratio length/width of head 0.86 (range 0.85– 0.87). Dorsal surface with punctures slightly sparser than in majority of species; sulcate longitudinal midline visible for almost all cephalic length, although less notable in posterior half; front weakly foveate between antennal insertions. Temporal carina strongly developed from ventral to dorsal surface, ending in a big setiferous puncture. Eyes small, 0.4 times the cephalic lateral length, not protruding laterally. First antennomere almost as long as 2–3 combined, 3 slightly longer than 2 (1.25 times), 4 as long as wide, 5–10 transverse. Mandibles shorter than head (ratio 0.87, range 0.85–0.89); each with three teeth, basal tooth small but discernible, two middle teeth very close to each other, interspace C-shaped; base of each mandible with conspicuous mesh-like microsculpture; mandibular channel little to moderately developed, external margin not carinate but like impressed line, internal margin like impressed line that fades at level of the most apical tooth. Apical palpomere of maxillary palpi nearly 1.5 times longer than preapical palpomere; apical palpomere of labial palpi nearly 1.25 times longer than preapical palpomere. Head 1.18 times wider than pronotum (range 1.14–1.22). Neck, in ventral view, with three impressed lines not clearly visible and mesh-like microsculpture.

Thorax: each dorsal row of pronotum with four punctures; pronotum almost as long as wide (ratio 1.03, without variation) and slightly wider at anterior corners than at posterior corners (ratio 1.135, range 1.13–1.14). Scutellum with punctures wider than on elytra, both with punctures moderately dense. Prosternum with the area close to anterior margin transversally elevated and delimited posteriad by an impressed line. Intercoxal process of mesoventrite shield-shaped, apex acute and slightly projected anteriad; transverse discal ridge broadly V-shaped, with irregular sides, not meeting margin of intercoxal process laterally, apex acute, beak-shaped; area delimited by anterior margin of mesoventrite and discal ridge with a longitudinal carina along its entire length (similar to ephippiatus group); entire mesoventrite with microsculpture like wavy lines; area between intercoxal process and posterior margin covered by coarser, meshed microsculpture, except near posterior margin where there is again microsculpture like wavy lines ( Fig. 11j ). Profemur of males with external row of spines initiating at base and ending one third before apex, spines somewhat separated, short and black; internal row with spines initiating at base, but dissapearing after basal third and reappearing close to apex; space between row of spines with mesh-like microsculpture. Metafemur of males with two rows of spines well developed, external row from base until near apex, internal row ending slightly before; spines short, space between rows with conspicuous mesh-like microsculpture. Tarsomeres somewhat robust and flattened dorsally.

Abdomen: entire abdomen with punctures moderately dense; visible tergites 1–3 with posterior basal transverse carina well developed, adjacent area narrow and slightly depressed, from anterior margin to end of depression with rough mesh-like microsculpure, contrasting with fine microsculpture of wavy lines that cover remaining surface; in visible tergite 4 with coarse meshed microsculpure on almost all its basal half, in tergite 5 covering basal 1/3 and in tergite 6 only with fine microsculpture. Visible sternites 1–5 with posterior basal transverse carina well separated from anterior margin, not straight, with sinuations; with two types of microsculpure as in tergites. Male pregenital sternite slightly emarginate at posterior margin, emargination broadly V-shaped ( Fig. 16c ). Male genital sternite short (2.21 times longer than wide), weakly asymmetrical, anterior portion occupying 19% and posterior portion 81% of its length, apical emargination not deep ( Fig. 20c ). Abdominal styli slender, slightly curved at their external margin.

Aedeagus: length 1.13 mm; elongate shape; with fused paramere, almost as long as 1/2 of the aedeagus length, outline straight; apex convex, subacute in ventral view and more distinctly acute in lateral view; basal half slightly wider than apical half, although in lateral view this difference in width is more noticeable; internal sac slightly visible ( Fig. 24g ).

Variability. Only two male specimens were studied, their variation in measurements and ratios is presented in the redescription. In addition, it was observed that they can have the last or last two antennomeres lighter than rest of antennomeres and the longitudinal carina in the anterior part of the mesoventrite is slightly less developed in one specimen than in the second specimen.

Taxonomic comments. In the taxonomic comments of B. dichrous and B. cifuentesi it was indicated how to distinguish them from B. flavipennis . Furthermore, B. flavipennis is superficially similar to B. ephippiatus , from which it is easily distinguished by the presence of a well developed temporal carina, four punctures in each dorsal row of pronotum, tarsomeres not so much widened or dorsally excavated, and aedeagus with an elongate paramere. On the other hand, B. ephippiatus lacks the temporal carina, has more than five punctures in each dorsal row of the pronotum, tarsomeres are wider and somewhat excavated dorsally, and the aedeagus has a short paramere. The female holotype of B. flavipennis was not studied, but photographs in dorsal and ventral view provided by A. Kovalev (Zoological Institute of the Russian Academy of Sciences) were available. Additionally, we analyzed some photographs (NHM; shared by M. Chani Posse) of specimens of this species studied by Sharp (1885), so we have no doubts about the correct identification of this species.

Material examined (two males): Mexico: Hidalgo: “ Acatlán, Loma Larga, El Llano , cultivos, matorral xerófilo y encinos, 2097 m, N20°16’13”, W98°28’18”, en nopales podridos, 20-VII-2010, J. Márquez col.” ( CC- UAEH) .

Group 6: platypterus

Included species: B. aenigmaticus sp. nov., B. iridescens Solsky, 1868 , B. juanmorronei sp. nov., B. nigerrimus Bernhauer, 1918 , B. optatus ( Sharp, 1885) , and B. platypterus ( Sharp, 1885) .

Diagnosis of the platypterus group: without any of the male sexual structures indicated in the previous groups, except B. aenigmaticus which has the metatrochanter acute apically; head without temporal carina; mandibles with a middle tooth and a basal tooth well separated from each other, both in dorsal position (in two species the left mandible has two middle teeth close to each other, interspace C-shaped, in addition to the basal tooth; Fig. 9f ); head shape subquadrate or transverse (ratio length/width 0.76–0.97; Fig. 10d ); mandibles 0.75 to 1.4 times as long as cephalic length; tarsomeres somewhat flattened dorsally; aedeagus with reduced paramere ( Figs. 24h–l , 25a ).

Key to Mexican species of Belonuchus of the platypterus group

1 Pronotum reddish ( Figs. 7f, 7g ); first two visible abdominal segments, sixth and genital segment reddish to yellowish; first three antennomeres reddish......................................................................... B. iridescens

- Pronotum black (e.g., Fig. 8c ); entire abdomen black or first four visible abdominal segments reddish and subsequent two black (except anterior border of fifth visible segment); first three antennomeres black.................................... 2

2(1) Elytra, legs and first four visible abdominal segments reddish ( Figs. 8a, c )........................................ 3

- Elytra, legs and first four visible abdominal segments black ( Figs 8b, d, e )........................................ 4

3(2) Cephalic dorsal surface with punctation less dense ( Fig. 8a ); dorsal rows of pronotum with five or six punctures (exceptionally seven in one or both rows) that cover 3/4 of the pronotal length ( Fig. 8a ); scutellum reddish to brown; male pregenital sternite slightly less deeply emarginate at posterior margin ( Fig. 16d ); aedeagus with apex moderately acute and with conspicuous internal sac ( Fig. 24h )...................................................................... B. aenigmaticus

- Cephalic dorsal surface with punctation denser ( Figs. 10g, j ); dorsal rows of pronotum with seven to nine punctures that cover the main part of its length ( Fig. 10j ); scutellum black; male pregenital sternite slightly more deeply emarginate at posterior margin ( Fig. 16–o ); aedeagus with apex acute and internal sac slightly visible ( Fig. 24k )...................... B. optatus

4(2) Last two visible abdominal segments reddish ( Fig. 8d ); left mandible with two middle teeth of small size very close to each other, interspace C-shaped ( Fig. 9f ); tarsomeres notably flattened dorsally; male pregenital sternite not emarginate at posterior margin ( Fig. 15f ); male genital sternite moderately elongate (2.6 times longer than wide) ( Fig. 20h ); aedeagus as in Fig. 24–l.......................................................................................... B . platypterus

- Entire body black ( Figs. 8b, e ); left mandible with a basal tooth and a middle tooth well separated from each other ( Fig. 10f ); tarsomeres moderately flattened dorsally; male pregenital sternite weakly emarginate at posterior margin ( Figs. 16e, f ); male genital sternite and aedeagus different from above........................................................... 5

5(4) Head transverse, slightly ovoid, with convex vertex, in lateral view without microsculpture like irregular lines under and behind each eye ( Fig. 10f ); male mandibles as long as, or longer than head; eyes nearly 0.5 times the cephalic lateral length; body surface glossy ( Fig. 8b ); male genital sternite short (2.14 times as long as wide), very asymmetrical ( Fig. 20f ); aedeagus as in Fig. 24j................................................................................... B . nigerrimus

- Head almost as long as wide, shape rectangular, slightly widened at posterior corners, vertex not convex, in lateral view with irregular lines under and behind each eye ( Fig. 8e ); mandibles in both sexes shorter than head; eyes less than 0.5 times the cephalic lateral length; body surface more dull (Fig, 8e); male genital sternite very elongate (3.47 times longer than wide), moderately asymmetrical ( Fig. 20i ); aedeagus as in Fig. 25a....................................... B . juanmorronei

Figures

FIGURE 7. Dorsal view of males (except figures d and f) of: a) Belonuchus cifuentesi (paratype), b) B. dichrous (NHM©, Biologia Centrali-Americana), c) B. dichrous, d) B. flavipennis (female holotype shared by A. Kovalev©), e) B. flavipennis, f) B. iridescens (female holotype shared by A. Kovalev©), g) B. iridescens. Scale bars = 2.5 mm.

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 10. Dorsal view of the head of males of: a) Belonuchus julietitae, b) B. singularis, c) B. connexus, d) B. platypterus, e) B. bidens, f) B. nigerrimus, g) B. optatus, h) B. cyanipennis, i) B. godmani. Dorsal view of the head and pronotum of the holotype female of: j) B. optatus.

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 15. Male pregenital sternite of: a) Belonuchus alternans, b) B. oxyporinus, c) B. tepoztecus, d) B. jalappensis, e) B. iridescens, f) B. platypterus, g) B. cyanipennis, h) B. apiciventris, i) B. linuzensis, j) B. metafemoralis, k) B. rufisternus, l) B. tenuistylus, m) B. bidens, n) B. pollens, o) B. longitarsus.

FIGURE 16. Male pregenital sternite of: a) Belonuchus moroni, b) B. dichrous, c) B. flavipennis, d) B. aenigmaticus, e) B. nigerrimus, f) B. juanmorronei, g) B. godmani, h) B. magnistylus, i) B. trochanterinus, j) B. rufipennis, k) B. basiventris, l) B. connexus, m) B. xanthomelas, n) B. ephippiatus, o) B. optatus.

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 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).

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).

FIGURE 29. Geographical distribution in Mexico of: a) B. linuzensis and Belonuchus sp. Q; b) B. cyanipennis, B. flavipennis and B. tepoztecus.