Ataenius trox Minkina & Skelley, 2025

Ataenius trox Minkina & Skelley , new species

( Figs 1A–E View FIGURES 1 )

Type locality. Brasil, Mato Grosso, Rio Bento Gomes, Pantanal ; 15°49’S, 56°31’W.

Type material. Holotype, female: Brasilien: Mato Grosso | Rio Bento Gomes | ( Pantanal ) | 1993–1994, E. Stuhr leg. || Flussabschnitt bei | Filisterra | 15°49’S | 56°31’W [ NHMW]. GoogleMaps

Description of the holotype (female). Dorsum ( Fig. 1A View FIGURES 1 ). Body oblong-ovate. Length: 4.85 mm; maximum width: 2.10 mm. Brownish-black, with somewhat lighter head and sides of pronotum; antennae, tarsomeres and mouth parts brown; whole body covered by argillaceous, greyish coating and dorsally with dense long and thick macrosetae.

Head ( Fig. 1D View FIGURES 1 ) distinctly convex, anteriorly weakly shiny with distinct microreticulation, rest of head covered by argillaceous, greyish coating; transversely trapezoidal; clypeus anterior margin widely, weakly sinuate with sides very widely rounded, not notched before genae, which are obtusely rounded and very distinctly exceeding eyes. Fronto–clypeal suture absent. Clypeus with dense, coarse, shallow punctation bearing long, thick, rounded at apex, brownish macrosetation.

Epipharynx ( Fig. 1E View FIGURES 1 ) transverse, with sides rounded, anterior margin weakly sinuate, with indistinctly produced corypha bearing four very short and very thin celtes at apex. Acanthopariae, acropariae, prophobae without chaetae. Chaetopariae, adelochaetae, chaetopediae with dense belts of long chaetae; chaetopariae and adelochaetae thick, chaetopediae thin. Epitorma somewhat bell–shaped. Tormae very long.

Pronotum entirely covered by argillaceous, greyish coating, distinctly convex, distinctly transverse, very slightly wider than base of elytra, widest in the middle. Anterior angles right-angled; sides very widely rounded, base of pronotum widely rounded before posterior angles. Anterior and posterior margins not bordered, sides not bordered. Sides and posterior margin with dense, long, thick, rounded at apex macrosetation; macrosetation of sides yellowish, lighter than macrosetation of pronotal surface. Punctation of pronotum simple, dense, coarse; punctures bearing long, thick, rounded at apex, brownish macrosetae which are arranged on slight ridges which are similar to some members of the family Trogidae .

Scutellum very small, triangular, entirely covered by argillaceous, greyish coating.

Base of elytra very weakly and narrowly bordered, with in distinct humeral denticles. Elytra elongate, distinctly convex, widest slightly after the middle. Elytra entirely covered by argillaceous, greyish coating, with ten striae and ten interstriae. Interstriae weakly convex; alternating interstriae with longitudinal, relatively higher tubercles; all interstriae with irregular rows of punctures bearing long, thick, rounded at apex, brownish macrosetation; longitudinal tubercles with tuft of very dense, very long, acute at apex macrosetae. Striae shiny, shallow, with distinct, not coarse, quite dense punctation; punctures of striae not encroaching on interstriae; striae variably connected before apex.

Pygidium with similar structure as abdominal ventrites.

Legs ( Figs 1A – C View FIGURES 1 ) all femora mat, with distinct microreticulation, with dense punctation bearing short, quite thin macrosetae. Profemora distinctly bordered anteriorly and posteriorly, meso- and metafemora bordered only before apex, anteriorly. Protibiae distinctly tridentate laterally, proximally serrulate, with dorsal side smooth; apical spur weakly downwardly bent before apex. Meso- and metatibiae with distinct accessory spine; metatibiae superior apical spur distinctly shorter than basal metatarsomere, latter slightly shorter than following four tarsomeres combined. Claws very short, thin, distinctly arcuate.

Macropterous.

Venter ( Fig. 1B View FIGURES 1 ). Metaventral plate entirely covered by argillaceous, greyish coating, very weakly convex, medially quite distinctly concave, with distinct, narrow, shallow longitudinal line in the middle; with dense punctation bearing short and thin macrosetae. Mesoventral plate small, shiny, strongly microreticulate, not covered by argillaceous, greyish coating; triangular, without any depression. Abdominal ventrites entirely covered by argillaceous, greyish coating; with quite dense, shallow punctation bearing very short, thick macrosetation; anterior margins narrowly, shallowly fluted.

Male. Unknown.

Etymology. The name of the new species is derived from the genus name Trox Fabricius, 1775 (Scarabaeoidea: Trogidae ) (noun in apposition), which has species with similar tuberculate and bristlely elytral intervals.

Differential diagnosis. With the whole body covered by argillaceous, greyish coating, Ataenius trox Minkina & Skelley , new species can confidently be included in the imbricatus species group (see Stebnicka 2003, 2007). Within the group, also Ataenius tuberculatus (Schmidt, 1911) has such distinct and large tubercles on the elytral intervals, with long macrosetation of the body. Ataenius trox Minkina & Skelley , new species has completely different body proportions (body much less elongated), much larger tubercles on the elytral intervals that have tufts of macrosetae, while in A. tuberculatus the tubercles are glossy and lack macrosetation. For comparison with A. tuberculatus see Figs 2A – F View FIGURES 2 .