Tachyina (Idiotachys), Motschulsky, 1862

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: 101-102

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scientific name

Tachyina (Idiotachys)

subgen. n.

Taxon classification Animalia Coleoptera Carabidae

Subgenus Idiotachys  subgen. n.

Type species.

Elaphropus acutifrons  sp. n.


Mentum without foveae; head with prominent keel-like frontoclypeal carina; elytral interneurs punctate, incomplete in length, and reduced in number; i8 visible only in apical half, interrupted and reduced.


Size. ABL = 2.15-2.2 mm; SBL = 2.25-2.325; TW = 0.95-1.0 mm.

Form. (Fig. 2G) Oval, compact, somewhat dorsoventrally compressed.

Color. Dark reddish brown, glabrous with some small punctules.

Microsculpture. Apparently absent, but difficult to see due to specimen condition.

Head. Mentum without deep foveae but with very faint, shallow impressions at base; frons (Fig. 3G) without longitudinal furrows but with keel-like medial carina between deep lateral depressions at clypeus; margin above antennal insertion prominent, with deep sinuate groove extending to midpoint of eye; labrum coarsely microsculptured; gula densely pitted.

Prothorax. Pronotum (Fig. 3G) transversely cordiform with sinuate, somewhat reflexed margins; pronotum nearly twice as wide as long at widest point; basal section sculpted with deep longitudinal wrinkles; posterior angles prominent, square, upturned; transverse impression dividing basal section from pronotal disc punctate, interrupted medially by deep, narrow excavation; medial furrow emerging from basal excavation, not reaching anterior margin; anterior transverse impressions lightly impressed, medially convergent; prosternum sulcate, with pair of prominent longitudinal ovoid bumps; procoxae separated by broad, apically rounded prosternal process; protibial apicolateral notch (Fig. 2G) oblique, rounded, not abrupt as is typical across Elaphropus  , not bearing spine.

Pterothorax. Mesepisternum neither foveate nor perforate; elytral interneurs 1-2 punctate, with second effaced near apex; i3 only very faintly impressed (Figs 2G, 5G); ARG very short, extending past Ed4; i8 (Fig. 4G) interrupted, partially impressed, just visible near (but not passing through) Eo5 and 6, and between Eo7 and 8; elytron with 9 ombilicate and 4 discal setae; humeral setal insertions widely spaced along basal third of elytral margin.

Genitalia. Not examined.


Known only from the type locality of Santarém, Pará, Brazil.

Derivation of name:

Masculine. From the Greek adjective ídios (= “self/peculiar”), in reference to its unique combination of characters, and Tachys  , the nominate genus of the subtribe Tachyina  .


Based on its afoveate mentum and apicolaterally notched protibiae, the only known species of Idiotachys  is considered to be part of the greater Elaphropus  complex. The overall proportions, reduced and punctate elytral strial interneurs, reduced 8th interneur, and arrangement of humeral elytral ombilicate setae diagnostic for the species described below preclude its placement in any existing Elaphropus  subgenus.

These, along with unique external characters, support Idiotachys  as a lineage distinct from either Tachyura  or Barytachys  , the two subgenera it most closely resembles.