Leptomyrmecini Emery, 1913

Dlussky, Gennady, Radchenko, Alexander & Dubovikoff, Dmitry, 2014, A new enigmatic ant genus from late Eocene Danish Amber and its evolutionary and zoogeographic significance, Acta Palaeontologica Polonica 59 (4), pp. 931-939 : 932

Tribe Leptomyrmecini Emery, 1913 Genus Usomyrma nov.

Type species: Usomyrma mirabilis sp. nov., by monotypy; see below.

Etymology: From Russian us, moustache (that often means antennae of insects in Russian) combined with the Greek myrmecos, ant, to indicate the peculiar structure of antennae of the genus.

Diagnosis.—Body slender, with long appendages. Antennae 13-segmented, second funicular segment is extremely long and curved, longer than any other antennal segments, including scape and terminal segment. Eyes big, reniform (i.e., their inner margin distinctly concave anteriorly). Mandibles elongate-triangular, masticatory margin quite long, with long and pointed apical tooth and at least five smaller though sharp following teeth (exact number of teeth is not properly visible), apices of mandibles crossed. Maxillary palps 6-segmented, labial palps 4-segmented. Fore wing with well developed pterostigma and closed cells (1+2r)+mcu and 3r; cell 3r wide. Middle and hind tibiae with very big, but not pectinate spur.

Remarks.—By the main morphological features, i.e., 13-segmented antennae, long and slender body and appendages, shape of mandibles, 6-segmented maxillary and 4-segmented labial palps, and especially by the structure of antennae and character of wing venation, Usomyrma certainly belong to the tribe Leptomyrmecini (for more details see discussion, below).

Stratigraphic and geographic range.—Late Eocene Amber, Denmark.