Belonuchus iridescens Solsky, 1868

Márquez, Juan & Asiain, Julieta, 2022, Taxonomy of the Mexican species of Belonuchus Nordmann (Coleoptera: Staphylinidae), Zootaxa 5152 (1), pp. 1-129 : 78-79

Belonuchus iridescens Solsky, 1868

Figs. 7f, g , 11m , 13i , 15e , 20e , 24i , 32b

Belonuchus iridescens Solsky, 1868: 140 .

Philonthus latecinctus Sharp, 1885: 415 , new synonymy. Belonuchus latecinctus comb. nov. ex Philonthus ( Chani-Posse et al. 2018b) .

Total body length 7.3 mm. Body reddish, except for head (excluding antennae and mouthparts), major part of third visible abdominal segment (except its anterior border), entire fourth and anterior 2/3 of fifth. Rest of body black. Antennomeres 4–10 dark, almost black.

Head: subquadrate, ratio length/width 0.91. Sulcate longitudinal midline slightly visible in less than anterior half of head; front weakly foveate. Eyes small, 0.41 times the cephalic lateral length, slightly protruding laterally. First antennomere almost as long as antennomeres 2–3 combined, 2 slightly shorter than 3, 4 slightly elongate, 5 as long as wide, 6–10 transverse. Mandibles shorter than head (ratio 0.76), left mandible with two middle teeth very close to each other and right mandible with one middle tooth, without basal tooth; mandibular channel slightly developed, external margin slightly defined, internal margin like very fine carinate line extending forwards beyond level of most apical tooth. Apical palpomere of maxillary and labial palpi slightly more than 1.5 times longer than preapical palpomere. Head 1.27 times wider than pronotum. Ventral surface with very fine and sparse punctures.

Thorax: pronotum with five punctures in each dorsal row; 1.1 times longer than wide; 1.1 times wider at anterior corners than at posterior corners. Scutellum with punctures slightly wider than, and almost as dense as on elytra, where punctures are fine and moderately dense. Prosternum without any evident elevation near anterior margin. Intercoxal process of mesoventrite scutellum-shaped, somewhat projected downwards; transverse discal ridge crenulate, not meeting margin of intercoxal process laterally ( Fig. 11m ). Protibia without aligned spines at external margin, only with two to four moderately large spines near apex. Tibiae of all legs with black spines contrasting with the reddish color of legs. Posterior legs without modifications ( Fig. 13i ). Tarsomeres flattened dorsally.

Abdomen: visible tergites 1–3 with posterior basal transverse carina well developed; adjacent area weakly depressed (tergites 1–2) to almost flat (tergite 3), narrow, with sparse wide-superficial punctures combined with fine punctures that are moderately dense; outside depressions and remaining tergites only with dense, fine punctures; visible tergites 3–5 with anterior part (1/3 to 1/4) with mesh-like microsculpture, which is different than microsculpure like wavy lines on their remaining surface. Visible sternites 1–3 with posterior basal transverse carina, which is not visible in sternites 4–6; all sternites covered with dense, fine punctures; microsculpture as on tergites. Male pregenital sternite only slightly emarginate medio-apically ( Fig. 15e ). Male genital sternite very elongate (3.41 times longer than wide), weakly asymmetrical, anterior portion occupying 56% and posterior portion 44% of its length, apical emargination deep ( Fig. 20e ). Abdominal styli slender.

Aedeagus: small, length 0.85 mm; elongate shape, apex very narrow and slightly curved backward; basal half slightly wider than apical half; internal sac slightly visible ( Fig. 24i ).

Variability. Unknown, only one male specimen was studied.

Taxonomic comments. Belonuchus iridescens is easily distinguished from the rest of species of the platypterus group by its coloration pattern (first three antennomeres, pronotum, first two visible abdominal segments, sixth and genital segment reddish to yellowish), its small size (close to 7 mm) and the black spines of tibiae that contrast with the reddish color of legs ( Fig. 7g ), characteristics that do not appear in any other species of this group.

Information from the original description of B. iridescens and B. latecintus was compared, a photo of the holotype of the first species (provided by A. Kovalev, Zoological Institute of the Russian Academy of Sciences) and a photo of lectotype of the second species ( Chani-Posse et al. 2018b) were analyzed, as well as the study of a specimen recently collected in Oaxaca (IEXA), and it was concluded that they are the same species, so the name Philonthus latecinctus Sharp, 1885 is proposed as junior synonym of B. iridescens Solsky, 1868 .

The following are some relevant characters coincident in the original descriptions of B. iridescens Solsky (1868) and Philontus latecinctus Sharp (1885) , which support the synonymy here proposed: total body length 5.5–7.0 mm; body bright reddish, head shiny, metallic-iridescent black, mandibles red, antennal apex and ante-apical segments of abdomen black, first three antennomeres red, last dark brown, pronotum shiny metallic-iridescent red, elytra testaceous-reddish, abdomen testaceous red, except segments 3–4 and margin of 5 that are black, prosternum red, legs red-testaceous; head quadrate; series of five dorsal punctures on the pronotum, in addition, with five punctures on margins of both sides; elytra with fine punctures, pubescence yellow (golden), dense and sub-opaque; abdomen with numerous punctures; without evident sexual dimorphism.

Type material. The female holotype of B. iridescens Solsky was not studied, but the dorsal and ventral view were analyzed in a photograph provided by A. Kovalev (Zoological Institute of the Russian Academy of Sciences). Type material of B. latecinctus Sharp was not studied, but a photograph of the lectotype designated by Chani-Posse et al. (2018b) was analyzed. Additional material examined (one male): Mexico: Oaxaca: “Uluapan, 4 km NE Ayautla, N18.05956°, W96.64558°, +- 10 a 420 m, 9 a 16-VI-2016, M. García et al., cols. / Lowland rainforest, Malaise trap” (m 1, IEXA).

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 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 13. Ventral view of the left posterior leg of males of: a) B. trochanterinus, b) B. tenuistylus, c) B. zunilensis, d) B. rufipennis, e) B. mixtecus, f) B. pollens, g) B. ephippiatus, h) B. aenigmaticus, i) B. iridescens, j) B. viridipennis. Tarsomeres of posterior leg of males of: k) B. colon, l) B. ephippiatus. Yellow ovals: median longitudinal groove.

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 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 32. Geographical distribution in Mexico and Guatemala of: a) Belonuchus cifuentesi, B. connexus and B. pectinipes; b) B. dichrous, B. iridescens and B. xanthomelas.