Belonuchus singularis, Márquez & Asiain, 2022

Márquez, Juan & Asiain, Julieta, 2022, Taxonomy of the Mexican species of Belonuchus Nordmann (Coleoptera: Staphylinidae), Zootaxa 5152 (1), pp. 1-129 : 44-45

Belonuchus singularis sp. nov.

http://zoobank.org/NomenclaturalActs/2d7c5032-465d-4813-b5b9-334da1d5d068

Figs. 3h , 10b , 14a, e , 17g, 18n, 22e, 26b

Total body length 11.2 mm. The only known specimen might be teneral, thus, what is indicated here as reddishbrown could be black. Reddish-brown on head, antennae, mandibles, neck, pronotum and prosternum. Third and fourth visible abdominal segments irregularly reddish-brown, with some borders lighter. Reddish on maxillary and labial palpi, elytra, scutellum, mesoventrite, metaventrite, legs, visible abdominal segments 1–2 and 5–6, genital segment and styli.

Head: transverse, ratio length/width 0.62. Dorsal surface with central part of front notably foveate, fovea crossed by sulcate longitudinal midline of head, this later is clearly visible in the fovea and slightly visible backward ( Fig. 10b ). Eyes slightly more than 0.5 times the cephalic lateral length, slightly protruding at sides. Antennomere 4 elongate, 5 almost as long as wide, 6–10 transverse. Mandibles very long, 1.7 times longer than head; with a basal tooth and a middle tooth, widely separated; mandibular channel well developed, with external margin well separated from internal margin at base, internal margin carinate, extending beyond level of middle tooth. Apical palpomere of maxillary and labial palpi nearly 1.5 times longer than preapical palpomere. Head 1.35 times wider than pronotum. Neck with moderate wrinkled microsculpture ventrally.

Thorax: left dorsal row of pronotum with five punctures and right dorsal row with six punctures; pronotum almost as long as wide (ratio 1.03) and slightly wider at anterior corners than at posterior corners (ratio 1.1). Scutellum with dense punctures, slightly wide and superficial. Elytra with similar punctures as on scutellum, but slightly less dense. Prosternum with an elevated transverse zone near to anterior margin. Intercoxal process of mesoventrite shield-shaped; transverse discal ridge irregular, slightly acute posteriorly. Profemur with external row of spines initiating distant from base and ending distant from apex, spines not dense and of moderate size; internal margin with few spines only near apex. Metatrochanter modified like a hook that is projected until near 1/2 of length of metafemur; metafemur flattened to slightly convex at area of overlap with hook; metatibia curved on internal margin, near midlength. Tarsomeres flattened dorsally.

Abdomen: first visible tergite with posterior basal transverse carina well developed, visible tergites 2–3 with posterior basal transverse carina somewhat faint; depressed adjacent zone well developed, with dense wide-superficial punctures; remaining parts of abdomen only with fine, moderately dense punctures ( Fig. 14a ). Male pregenital sternite with distinct V-shaped emargination at posterior margin (Fig. 17g). Male genital sternite short (2.33 times longer than wide), moderately asymmetrical, anterior portion occupying 40% and posterior portion 60% of its length, apical emargination deep and wide ( Fig. 18n ). Abdominal styli moderately wide.

Aedeagus: length 1.6 mm; elongate shape; apex wide and convex, sides slightly narrowed in anterior third and then gradually widened towards base; basal half moderately wider than apical half; internal sac visible ( Fig. 22e ).

Variability. Could not be assessed due to availability of only one specimen.

Taxonomic comments. Due the color pattern of the abdomen, combining reddish and dark-reddish segments, this species resembles some species of Paederomimus . This is the only Mexican species of Belonuchus with the third and fourth visible abdominal segments dark and fifth and sixth segments pale, all the other species with dark segments have them apically.

Etymology. The name refers to the fact that only a single specimen of this species was available.

Type material: Holotype (male, FMNH): “ México, Oaxaca, 12 mi S de Valle Nacional , 3200 ft, 17°41’N, 96°19´W, 22-31-VII-1971 / tropical subevergreen forest, carrion trap (squid), A. Newton, 302Cs/ Belonuchus det. Newton, 1995”.

Figures

FIGURE 3. Dorsal view of males of: a) Belonuchus magnistylus (paratype), b) B. metafemoralis (paratype), c) B. oxyporimimus (paratype), d) B. pulcher (paratype), e) B. oxyporinus (holotype, NHM©), f) B. oxyporinus, g) B. rufisternus (holotype), h) B. singularis (holotype). 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 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 22. Ventral (left) and lateral (right) view of the aedeagus of: a) Belonuchus oxyporimimus, b) B. oxyporinus, c) B. pulcher, d) B. rufisternus, e) B. singularis, f) B. tenuistylus, g) B. tepoztecus (at center detail of the paramere), h) B. trochanterinus, i) B. zunilensis. Scale bar = 0.5 mm (all figures).