Tachyina (Ammotachys), Boyd, Olivia F. & Erwin, Terry L., 2016

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 : 98

Taxon classification Animalia Coleoptera Carabidae

Subgenus Ammotachys subgen. n.

Type species.

Elaphropus marchantarius sp. n.

Diagnosis.

Mentum lacking foveae; elytron (Fig. 5F) with 8 micropunctulate interneurs; elytral humeral margin serrate; basal half of i8 (Fig. 4F) parallel to elytral margin, meeting or nearly reaching humeral series of setal insertions; humeral setae symmetrically distributed; apical half of i8 curvy, abruptly bent around Eo5+6 and Eo7; apical recurrent groove (Fig. 1E) rudimentary, continuous with i3.

Description.

Size. ABL = 2.25-2.8 mm; SBL = 2.35-2.9 mm; TW = 0.95-1.15 mm

Form. Elongate, parallel-sided, subdepressed.

Color. Uniformly yellow-brown to flavous.

Microsculpture. Head and anteromedial part of pronotum with coarse, scaly, isodiametric microsculpture; remainder of pronotum and elytron with linear, transverse microsculpture.

Head. Mentum without foveae.

Prothorax. Basal section of pronotum (Fig. 3F) triangular, rugose, with basal transverse impressions not well-defined; pronotum with dark, medial furrow that does not reach anterior margin; pronotal furrow with shallow basal excavation; convergent transverse impressions barely visible along anterior margin of pronotum; basal protarsomere of male with prominent medial dentiform expansion.

Pterothorax. Elytral margin serrate; humeral margin (Fig. 4F) with four symmetrically spaced setal insertions; elytron with 8 micropunctulate interneurs; i4-7 not reaching apex and i4-5 converging apically (Fig. 1E); basal half of i8 parallel to elytral margin, meeting or nearly reaching humeral series of setae; apical half of i8 deeply impressed, abruptly curved around Eo5+6 and Eo7 and somewhat deviated medially from elytral margin; ARG (Fig. 1E) rudimentary, continuous with i3.

Genitalia. Not examined.

Distribution.

Widely distributed in the Amazon basin. Known from several localities along the Rio Negro (S. Venezuela), Rio Solimões (S. Colombia and Pará, Brazil), and their confluence, and the Rio Xingu (NE Mato Grosso, Brazil).

Derivation of name:

Masculine. Greek noun, ammos (= “sand”), in reference to the habitat and coloration of the known species of this genus, and Tachys , the nominate genus of the subtribe Tachyina .

Remarks.

Though these beetles are tentatively placed within Elaphropus due to the afoveate mentum, their remarkable (though perhaps homoplasious) resemblance to the foveae-bearing species Meotachys (Scolistichus) riparius , calls into question the long-assumed taxonomic value and phylogenetic distribution of this character. These two species have similarly broad, pan-Amazonian, apparently overlapping distributions. Molecular data should help to clarify whether their shared morphologies are due to convergence of separate lineages or the loss or gain of foveae within a lineage.