Vaquerister cantador Caterino and Tishechkin, 2022

Caterino, Michael S. & Tishechkin, Alexey K., 2022, A New Genus and Species of Histerid Beetle from Western Mexico Showing a Remarkable Sexual Mesotibial Dimorphism (Coleoptera: Histeridae: Histerinae: Exosternini), The Coleopterists Bulletin 76 (3), pp. 357-363 : 358-362

Vaquerister cantador Caterino and Tishechkin , new species

zoobank.org/ urn:lsid:zoobank.org:act:444E3087-E4FC-4ABB-92E2-DDC941FAEBE0 ( Figs. 1–4 )

Type Material. Holotype male: “ MEXICO: Sonora, Rancho El Cajon, 40 km E Alamos, along Rio Cuchujaqui , 420m, 27 ° 03.00′N, 108 ° 43.91′W, x.1 -11.2006, M.E. Irwin, Taxodium riparian tropical deciduous forest”/“EXO-00182” (deposited in FMNH) . Paratypes (4). 2 females, 1 male: “ MEXICO: Nayarit: Arroyo Santiago , 3mi. N.W. Of Jesus Maria , VII.6.1955, Leg. B. Malkin ”/“in dead rotten cactus”/“EXO-00813” ; 1 male: “ Mexico: Sonora, 13mi SE Alamos , Oct. 30 1972, K.Stephan leg.” ( FMNH, CASC, MSCC, CSCA) .

Description. Size range: Length 3.1–3.5 mm; width 2.7–2.9 mm. Body: Black, elongate oval, dorsally convex, generally smooth with fine but conspicuous ground punctation; frons shallowly depressed at middle, prominent over antennal bases, lacking frontal and supraorbital striae, striae present along the inner edges of eyes only; vertex of head with fine transverse ridges forming a stridulatory file on each side, extending nearly to upper corner of eye, hidden when head is retracted; labrum broad, weakly emarginate; left mandible with small tooth at base of incisor edge, right mandible edentate; antennal club tomentose, with fine subapical annulus, slightly widened at middle of upper and lower surfaces, and small tomentose patches on both surfaces distad the annulus. Submentum depressed, defined by a posterior carina; mentum setose, rounded at corners and shallowly emarginate at middle.

Prothorax widest at base, sides evenly rounded to anterior corners, anterior margin weakly produced above head; disc with very weak prescutellar impression and irregular series of punctures along basal margin, laterally densely secondarily punctate; submarginal pronotal striae absent; pronotum with just a single pair of anterior gland openings, small and located just behind the crenulate anterior marginal stria; prosternal keel broad at base, weakly emarginate, in male posteriorly swollen with prominent pair of setose foveae in basal corners, carinal striae complete, weakly or not meeting anteriorly; prosternal lobe rather long and narrowly rounded, marginal stria fragmented.

Elytron with one deeply impressed epipleural stria; outer subhumeral stria nearly complete, slightly abbreviated at base; inner subhumeral stria absent; dorsal striae 1–4 complete, the fourth arched at base nearly to suture; dorsal stria 5 short, fragmented, present in no more than posterior onefourth; sutural stria present in posterior two-thirds. Anterior margin of mesoventrite of female broadly emarginate with weak median bump projecting anteriorly, male anterior mesoventral margin more deeply emarginate, without obvious median process; marginal mesoventral stria complete; meso-metaventral stria of female complete across middle, fine, that of male absent; metaventrite of female simple, weakly convex, that of male rather broadly depressed, with very fine but distinctly flattened setae on either side of midline; inner lateral metaventral stria present in both sexes, extending to inner third of metacoxa; postmesocoxal stria short, generally lost in punctures posterolaterad coxa; recurrent stria of lateral metaventral disc present along metepisternal margin, not reaching inner lateral metaventral stria at middle.

Protibia rather narrowly elongate, outer margin rounded and weakly dentate, with 7–8 small spines along margin; two small protibial spurs present; protarsomeres with pair of fine ventral spines in female, with inner and especially outer setae of males expanded and laminate; mesotibia of female with outer margin weakly rounded, with ~7 fine marginal spines, also with second series of submarginal spines distinctly separated from marginal spines; mesotibia of male with deep, nearly circular subapical emargination along outer margin; metafemur of female with anterior and posterior margins more or less parallel, weakly produced near apex of posterior margin; metatibia of female very similar to mesotibia, with divergent series of marginal and submarginal spines; male metafemur more elongate, distinctly swollen near apex of posterior margin; male metatibia widest just beyond middle, unevenly narrowed toward apex, with marginal series of spines largely obsolete; meso- and metatarsomeres of both sexes with series of 3–4 setae along inner margins and 1–2 on outer margins; all tarsal claws paired, evenly curved, “normal” for tribe.

Propygidium large, about three-fourths length of pygidium along midline, more or less evenly covered with small secondary punctures; pygidium with secondary punctures diminished in size and density toward apex.

Male tergite VIII with narrow basal emargination, membrane attachment line just distad its upper arc, sides subparallel, apical margin deeply, narrowly emarginate; sternite VIII short, apical lobes flattened, with broad membranous lobes bearing a dense field of long setae for most of their widths; sides of tergite IX rounded, but with blunt wing-like processes; tergite X long, completely divided along midline; sternite IX with rather even-width stem, apical arms upturned and with short recurved apical edges; aedeagus small, shorter than tergite VIII, flattened, slightly dorsoventrally curved, sides sinuately narrowed to apex, apex subdivided, with lateral cleft, dorsally divided along midline for apical one-third; venter weakly sclerotized, but with long, detached V-shaped sclerite, projecting slightly beneath; basal piece short, distal margin of venter projecting slightly.

Female ovipositor/genitalia with elongate, paddleshaped valvifers, strong tridentate coxites; bursa copulatrix unsclerotized, short; spermatheca a simple elongate, weakly expanded sac, finely annulate, bearing single filamentous spermathecal gland near the base of expanded portion of sac, gland inserted at junction of bursa and common oviduct.

Distribution and Ecology. The two known localities for this species span about 700 km from northwestern Nayarit to southeastern Sonora. Very generally the whole area might be termed seasonal subtropical forest. But that would belie the degree of local-scale variability with elevation, slope, and other factors. The fact that the series from Nayarit was collected in rotting cactus suggests that drier habitats are preferred. It is surprising, if that is a real preference, however, that more specimens have not been collected, as considerable work has been done on arthropods associated with rotting cactus in the deserts of southwestern North America ( Ferro et al. 2013; Pfeiler et al. 2013; Pfeiler and Markow 2011), including a couple of papers specifically dealing with histerids ( Pfeiler et al. 2010; Reese and Swanson 2017). The specimen collected by Mike Irwin was collected in a Malaise trap, itself an unusual event for a histerid, which tend to fall rather than climb. In summary, it is difficult to say whether this is a truly cactophilic species, or one that was only found in such an association incidentally.

Etymology. Together the genus and species names mean “the singing cowboy hister”, in reference to the spurs on its legs, and the stridulatory apparatus on its head.

Figures

Fig. 1. Vaquerister cantador, new species, habitus photos of male. A) Dorsal view, B) Ventral view, C) Anterior view of head and prothorax, D) Lateral view, E) Posterior view of propygidium and pygidium.

Fig. 2. Vaquerister cantador, new species, scanning electron micrographs of male. A) Ventral view of mouthparts, B) Protarsus, C) Lateral view of prosternum, D) Anterior view of head, with white arrows pointing to stridulatory files, E) Mesotibia, F) Metafemur and metatibia.

Fig. 3. Vaquerister cantador, new species, male genitalia. A) Dorsal view of tergite VIII, B) Dorsal view of sternite VIII, C) Dorsal view of tergites IX and X, D) Dorsal view of sternite IX (spiculum gastrale), E) Dorsal view of aedeagus, F) Lateral view of aedeagus.

Fig. 4. Map of known localities for Vaquerister cantador, new species.