Belonuchus longitarsus, Márquez & Asiain, 2022

Márquez, Juan & Asiain, Julieta, 2022, Taxonomy of the Mexican species of Belonuchus Nordmann (Coleoptera: Staphylinidae), Zootaxa 5152 (1), pp. 1-129 : 66-67

Belonuchus longitarsus sp. nov.

http://zoobank.org/NomenclaturalActs/626c6ef1-78df-4c53-8d04-5808d68b4b92

Figs. 6a , 11g , 15–o , 19–l , 23i , 27b

Total body length 8.4 mm. Black on head, mandibles, pronotum, scutellum and mesoventrite. Antennae almost black, with some irregular parts brown. Maxillary and labial palpi reddish-brown. Prosternum black with some parts brown. Elytra, legs and abdomen reddish-brown, with elytra shinier than remaining body.

Head: slightly transverse (ratio 0.86) and dorsally slightly convex. Dorsal surface with sparse punctures, about ten in each half, distributed as in majority of species; sulcate longitudinal midline weakly visible in anterior half of head; front slightly foveate between antennal insertions. Posterior corners with some setae and roughness, remotely resembling a temporal carina. Eyes small, 0.38 times the cephalic lateral length, weakly protruding laterally. Antennomeres 4–6 elongate, 7–10 almost as long as wide. Mandibles slightly shorter than head (ratio 0.92), with two teeth (basal and middle) well separated between them, middle tooth of right mandible the longest; mandibular channel with external margin expanded at base and widely separated from internal margin for almost all its length, internal margin carinate and extending to level of middle tooth, where follows forward like impressed line. Ventral surface of head with sparse, fine punctures at posterior corners. Head 1.2 times wider than pronotum.

Thorax: pronotum with five punctures in each dorsal row, irregularly aligned and spaced; pronotum slightly longer than wide (ratio 1.17) and slightly wider at anterior corners than at posterior corners (ratio 1.1). Scutellum black, with microsculpture like wavy lines and punctures denser than on elytra, but concentrated at center. Elytra shiny, with punctures somewhat sparse, with remarkable yellowish setae. Prosternum elevated near anterior margin and separated from middle and posterior area (that also are elevated) by a faint constriction. Intercoxal process of mesoventrite narrowly triangular, with apex acute; transverse discal ridge well defined, broadly V-shaped, meeting margin of intercoxal process laterally ( Fig. 11g ). Middle and posterior legs long and slender. Profemur with external row formed by nine to ten spines that initiate almost at mid length and end before apex, last external spine not reaching level of six or seven apical spines of internal side of femur; spines reddish, longest spines of external margin as long as spines of protibiae. Males and females with middle and posterior legs without modifications. Tarsomeres elongate, metatarsus slightly shorter to almost as long as metatibiae; only the last tarsomere is slightly flattened dorsally. Tarsal claws longer, almost as long as second tarsomere.

Abdomen: visible tergites 1–2 with posterior basal transverse carina complete and very closer to anterior margin, tergite 3 with posterior basal transverse carina incomplete, only clearly visible at sides; adjacent area moderately depressed and wide, with punctures slightly wide combined with dense, fine punctures, that cover also remaining surface of these tergites as well as tergites 5–6; tergite 4 with anterior half with some wide punctures combined with fine punctures and posterior half only with fine punctures. Sternites with similar punctures as on tergites, but wide punctures slightly denser. Male pregenital sternite weakly emarginate at posterior margin ( Fig. 15–o ). Male genital sternite moderately elongate (2.58 times longer than wide), very asymmetrical, anterior portion occupying 20% and posterior portion 80% of its length, apical emargination moderately deep ( Fig. 19–l ). Abdominal styli slender.

Aedeagus: length 1.1 mm; cone-shaped, sides not gradually but slightly angulately narrowed towards apex; apex subacute; basal half wider than apical half, although this gradually becomes narrower; internal sac visible ( Fig. 23i ).

Variability. Total body length in males 9.1 mm (range 8.5–10.0 mm), in females 9.3 mm (range 9.2–9.4 mm); ratio length/width of head in both sexes 0.88 (range 0.88–0.89); ratio mandibular length/cephalic length in males and in females 0.96 (range 0.92–1.00); head in males 1.15 times wider than pronotum (range 1.14–1.17), in females 1.11 (range 1.11–1.12); ratio length/width of pronotum in males 1.17 (range 1.16–1.17), in females 1.18 (range 1.16–1.20); ratio anterior width/posterior width of pronotum in males 1.10 (range 1.10–1.11), in females 1.08 (range 1.07–1.09). The color of antennae and prosternum is black with some irregular brown parts, the apical half of mandibles can be reddish and metaventrite can be reddish-brown. In females there are six punctures in one of the two dorsal rows of pronotum and five in the second row.

Taxonomic comments. This species can be confused with B. rufiventris and it is distinguished from this species by having five or six punctures in each dorsal row of pronotum, small eyes (0.38 times the cephalic lateral length), reddish coxae, elytra and abdomen with dense fine setae, third visible abdominal tergite with posterior basal transverse carina inclomplete, male pregenital sternite moderately emarginate at posterior margin, and aedeagus 1.1 mm of length, with apex moderately acute, and sides narrowed apicad with a slight angle ( Fig. 23i ). Conversely, B. rufiventris has only two punctures in each dorsal row of pronotum, eyes slightly longer than 0.5 times the cephalic lateral length, coxae black or dark-brown, elytra and abdomen with fine and sparse setae, third visible abdominal tergite with posterior basal transverse carina well developed, male pregenital sternite deeply emarginate at posterior margin and aedeagus 1.3 mm of length, with a faint contriction near base, apex very acute, and sides converging in almost straight line toward acute apex ( Fig. 24a ). It is worth mentioning that the four studied specimens of B. longitarsus were in bad condition, possibly due to the fact that they were collected dead in a rodent nest. The long legs and claws (especially the tarsomeres), and its similarity to B. rufiventris (which has also been collected in gophers’ nests), suggests that this species may be a specialized associate of rodent nests.

Etymology. The name of this species is derived from a combination of the words “longus” and “tarsus”, and refers to the very long tarsi, although it is not the only species with this character.

Type material (two males, two female): Holotype (male, IEXA) : “ México: Veracruz, Perote, Frijol Colorado , 2420 m, en nido de roedor, 6-VI-2015, E. Mora y L. Delgado cols.” The holotype lacks the last eight antennomeres of right antenna, the apical antennomere of left antenna, and in the right middle leg, lacks the tibia and tarsomeres . Paratypes: same data as holotype (m 1, f 1, IEXA; f 1, CC-UAEH) .

Figures

FIGURE 6. Dorsal view of males (except figure c) of: a) Belonuchus longitarsus (holotype), b) B. rufiventris, c) B. iteratus (male lectotype and female paralectotype, NHM©), d) B. xanthomelas (NHM©, Biologia Centrali-Americana), e) B. xanthomelas, f) B. ephippiatus, g) B. moroni (paratype). 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 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 19. Male genital sternite of: a) Belonuchus tepoztecus, b) B. trochanterinus, c) B. zunilensis, d) B. bidens, e) B. erichsoni, f) B. jalappensis, g) B. mixtecus, h) B. pollens, i) B. rufipennis, j) B. basiventris, k) B. connexus, l) B. longitarsus, m) B. rufiventris, n) B. xanthomelas, o) B. ephippiatus, p) B. moroni. Scale bars = 0.5 mm.

FIGURE 23. Ventral (left) and lateral (right) view of the aedeagus of: a) Belonuchus bidens, b) B. erichsoni, c) B. jalappensis, d) B. mixtecus, e) B. pollens, f) B. rufipennis, g) B. basiventris, h) B. connexus (at center, detail of the apex of the median lobe), i) B. longitarsus (at center, detail of the apex of the median lobe). Scale bar = 0.5 mm (all figures).

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 27. Geographical distribution in Mexico of: a) Belonuchus erichsoni and B. oxyporinus; b) B. longitarsus, B. metafemoralis, B. mixtecus, B. optatus and B. rufiventris.