Tachyxysta Boyd & Erwin

Boyd, Olivia F. & Erwin, Terry L., 2016, Taxonomic review of New World Tachyina (Coleoptera, Carabidae): descriptions of new genera, subgenera, and species, with an updated key to the subtribe in the Americas, ZooKeys 626, pp. 87-123 : 96-97

Taxon classification Animalia Coleoptera Carabidae

Genus Tachyxysta Boyd & Erwin gen. n.

Type species.

Tachyxysta howdenorum Boyd & Erwin, sp. n.

Diagnosis.

Pronotum with distinctly inflated basal section separated from pronotal disc by subsulcate transverse impression; basal section interrupted at midpoint by prominent, deep excavation opposite scutellum; overall form robust, convex.

Description.

Size. ABL = 2.4-2.5 mm; SBL = 2.5-2.7 mm; TW = 1.15-1.25 mm.

Form. Compact, robust, convex.

Color. Dorsally piceous, unicolorous (Fig. 2I); antennae and legs lighter, rufotestaceous except for darker basal half of coxae; dorsally glabrous and without microsculpture except for labrum.

Head. Two pairs of supraorbital setae within channeled longitudinal frontal furrows; frons not raised between furrows, often with subtle transverse wrinkles (Fig. 3I); mentum without foveae.

Prothorax. Base of pronotum (Fig. 3I) with deep lateral depression near posterior angle; posterior angle of pronotum raised, prominent; basal section of pronotum convex, interrupted by deep medial excavation opposite scutellum; male without dilated basal protarsomere(s); protibia notched apicolaterally (Fig. 2I); tarsal claws simple, not denticulate.

Pterothorax.Elytral margin reflexed; i1 entire, subsulcate or faintly impressed; i2-i7 not visible; i8 striatiopunctate from humerus to Eo5, apically subsulcate (Fig. 4I); recurrent groove elongate, slightly sinuate, subparallel to elytral margin, and recurved anteriorly (Fig. 5I); surface without spots; elytral ombilicate setae 2, 6, and 8 more than twice as long as next longest seta.

Genitalia. male aedeagus robust, elongate, with unequally sized, apically 3- or 4-setose parameres (Fig. 6E).

Distribution.

The Mexican specimens were collected near or in El Ocote Preserve; the Honduran specimen was collected in an area near Comayagua National Park. Based on collection data from a limited number of specimens, Tachyxysta howdenorum may be restricted to higher altitudes.

Derivation of name.

Feminine. Derived from Tachys , the nominate genus of the subtribe Tachyina , and the Greek xustos (= “smooth/polished”), in reference to this species’ unmicrosculptured, glabrous dorsal surface and alluding to its general resemblance to some members of the subtribe Xystosomina , particularly those of the genus Erwiniana .