Syzeton gruberi, Gompel, 2022

Gompel, Nicolas, 2022, The genus Syzeton Blackburn, 1891 (Coleoptera, Aderidae) in the United States of America, Zootaxa 5162 (3), pp. 243-267 : 256

Syzeton gruberi n. sp.

( Figures 2f ; 3f ; 5f )

Etymology. This taxon is named after my good friend Jeffrey Gruber, who first collected it, in appreciation of his long-term support of my work and his generosity with sharing material.

Type locality. United States: Arizona, Cochise County, Coronado NF: Huachuca Mountains, Upper Sonoran zone, Carr Canyon [31°26’25” N 110°17’07” W] .

Distribution. United States: Arizona.

Description. Body length. ♂: 1.93± 0.08 mm (n=4) ♀: 2.21± 0.08 mm (n=4). Body brown to orange, elytra progressively darker toward apex, pronotum and head darker, appendages entirely orange.

Head. Transverse, dark-brown to black, slightly wider than pronotum. Frons convex. Palpi orange. Punctures sparse (spaces between punctures much wider than the puncture diameters), fine and superficial. Pubescence uniseriate, relatively long, spaced, hirsute, golden.

Eyes convex, bulging, separated from the posterior edge of the head in side view by a distance the width of two rows of ommatidia. Eyes emarginate, with a deep anterior notch where the antennae are inserted, separated from each other by less than one eye diameter in front view in both sexes.

Antennae. Thick, covered with thin and stout setae, 80% the length of elytra in ♂♂, ~70% in ♀♀, uniformely orange. Antennomeres 2–7 bead-shaped, longer than wide, antenommeres 8–10 weakly conical, somewhat elongated in ♂♂, subquadrate in ♀♀, regularly thicker toward apex. Last antennomere twice as long as penultimate, rounded.

Pronotum. Dark orange to nearly black. Subquadrate in ♂♂, transverse in ♀♀, regularly convex, pentagonal, with a straight base flanked by rounded posterior angles, sides straight, hardly diverging from base to apex, and apex composed of two segments converging toward the head insertion in an obtuse rounded angle. Surface densely and coarsely punctate, the space between punctures equal to, or smaller than the puncture diameters, punctures large, deep. Pubescence uniseriate, raised, hirsute, golden.

Elytra. Length. ♂: 1.39± 0.05 mm (n=3) ♀: 1.60± 0.08 mm (n=4). Elongate (width/length ♂: 0.52±0.04 (n=3) ♀: 0.56±0.01 (n=4), sides subparallel in both sexes, humeral angles well marked. Orange to pale brown, progressively infuscated in posterior half. Punctures dense, strong and deep, coarser than on the pronotum, space between punctures smaller than the puncture diameters. Disc weakly but regularly convex. Pubescence uniseriate, moderately long, raised, golden.

Legs. Simple, inconspicuous, orange. Foretibia straight and simple in both sexes, with a barely perceptible kink at apex in ♂♂ ( Figure 5f ).

Aedeagus ( Figure 3f ). Elongate, straight, sides subparallel in ventral view in the basal two thirds, then regularly tapered to the apex. Nearly straight along its dorsal side in lateral view. Apex terminated in a button in lateral view.

Sexual dimorphism. Weak sexual differentiation. Eyes more separated in ♀♀ than in ♂♂. Antennae shorter in females.

Type material. United States. Arizona: Cochise County, Coronado NF: Huachuca Mountains, Upper Sonoran zone, Carr Canyon (1670 m) [31°26’25” N 110°17’07” W], Evergreen oak-grassland habitat, Beaten from branches of hardwood tree, 9.VIII.2013, J. P. Gruber leg. (1 ♂ holotype and 3 ♂♂ paratypes, NGPC); Evergreen oak-grassland habitat, at side of stream, Beaten from branches of Quercus sp. or other hardwood tree, 10.VIII.2013, J. P. Gruber leg. (2 ♀♀ and 1 ♂ paratypes, WIRC; 1 ♀ paratype, NGPC) .

Figures

FIGURE 2. Habitus of US Syzeton species. a, Syzeton ouachitanus (Werner, 1990) ♂ from Texas. b, S. fasciatus (Melsheimer 1846) ♂ from Wisconsin. c, S. hubbardi (Casey 1895) ♂ from Oklahoma. d, S. nubifer (LeConte, 1878) ♂ from Texas. e, S. ater (LeConte, 1875) ♂ from Arkansas. f, S. gruberi n. sp. ♂ paratype from Arizona. g, S. arizonae n. sp. ♂ holotype from Arizona. h, S. belovi n. sp. ♂ holotype from Texas. i, S. pallidus (Werner, 1990) ♂ from Texas. j, S. subfasciatus (LeConte, 1855) ♂ from Missouri. k, S. floridanus (Werner, 1990) ♂ from Florida. l, S. signatus (Haldeman, 1848) ♂ from South Carolina. m, S. ouachitanus (Werner, 1990), elytral variation. n, S. hubbardi (Casey 1895), elytral variations, the white lines delinate a ~20º angle between the inner oblique markings. o, S. nubifer (LeConte, 1878), elytral variations, the white lines delinate a ~30–40º angle between the inner oblique markings. Scale bars: 1 mm.

FIGURE 3. ♂ genitalia of US Syzeton species in ventral view (left on all panels) and lateral view (right on all panels, ventral facing to the left). a, Syzeton ouachitanus (Werner, 1990) ♂ from Texas. b, S. fasciatus (Melsheimer 1846) ♂ from Wisconsin. c, S. hubbardi (Casey 1895) ♂ from Oklahoma. d, S. nubifer (LeConte, 1878) ♂ from Texas. e, S. ater (LeConte, 1875) ♂ from Texas. f, S. gruberi n. sp. ♂ paratype from Arizona. g, S. arizonae n. sp. ♂ holotype from Arizona. h, S. belovi n. sp. ♂ holotype from Texas. i, S. pallidus (Werner, 1990) ♂ from Texas. j, S. subfasciatus (LeConte, 1855) ♂ from Missouri. k, S. floridanus (Werner, 1990) ♂ from Florida. l, S. signatus (Haldeman, 1848) ♂ from South Carolina. Note the presence of air bubbles in some of the genitalia presented here. Scale bars: 0.1 mm.

FIGURE 5. External morphology of US Syzeton species. a–l, ♂ right foretibia in upper view. a, Syzeton ouachitanus (Werner, 1990) ♂ from Texas. b, S. fasciatus (Melsheimer 1846) ♂ from Wisconsin. c, S. hubbardi (Casey 1895) ♂ from Oklahoma. d, S. nubifer (LeConte, 1878) ♂ from Texas. e, S. ater (LeConte, 1875) ♂ from Texas. f, S. gruberi n. sp. ♂ paratype from Arizona. g, S. arizonae n. sp. ♂ holotype from Arizona. h, S. belovi n. sp. ♂ holotype from Texas. i, S. pallidus (Werner, 1990) ♂ from Texas. j, S. subfasciatus (LeConte, 1855) ♂ from Missouri. k, S. floridanus (Werner, 1990) ♂ from Florida. l, S. signatus (Haldeman, 1848) ♂ from South Carolina.Arrowheads indicate kinks or other modification of the inner side of the tibias; double black arrow denotes the curve of the tibia. m–n, ♀ antennae with details of antennomere 6–8 (inset). m, S. belovi n. sp. ♀ paratype from Texas. n, S. pallidus (Werner, 1990) ♀ from Texas. o, left hind-leg of S. fasciastus (from Wisconsin) in ventral view (arrow indicates the inflated femur). p–q, pubescence on elytral disc. p, S. belovi n. sp. ♂ holotype from Texas. q, S. arizonae n. sp. ♂ holotype from Arizona. Scale bars: 0.1 mm.