Eocenomyrma orthospina, Dlussky & Radchenko, 2006

Dlussky, Gennady & Radchenko, Alexander, 2006, A new ant genus from the late Eocene European amber, Acta Palaeontologica Polonica 51 (3), pp. 561-567 : 563

Eocenomyrma orthospina sp. nov.

Fig. 1 ; Tables 1, 2.

Derivation of the name: After Greek orthos —straight, and Latin spina —a spine, in relation to the shape of propodeal spines of this species.

Holotype: MZ 13434 , worker, complete specimen.

Locality and horizon: Baltic Amber, late Eocene.

Diagnosis.—Total length ca. 3–3.5 mm. The new species is characterised by the following apomorphies: frontal carinae are short, quite strongly curved and merge with the rugae, which surround antennal sockets; frons quite wide, frontal lobes rather big and extended laterally; mesosoma of moderate length, not robust, not constricted behind so that propodeum not much narrower than promesonotum, metanotal groove distinct but shallow (seen in profile), promesonotal suture invisible (seen from above); propodeal spines quite long, not widened at the base, slender, more or less straight, pointed at the tips, directed backward and upward at an angle about 45 °, and feebly divergent (seen from above); petiole much longer than high, with very long peduncle, petiolar node with rounded dorsum, without dorsal plate; frons with not coarse longitudinal, slightly sinuous rugae, lateral parts of head dorsum and occiput with reticulation; mesosoma with quite coarse reticulation (the sculpture of petiole is invisible).

By the complex of these features Eocenomyrma orthospina differs from the all known species of the genus Eocenomyrma , particularly from E. elegantula , which has a finely reticulated, not rugose body. It clearly differs from E. rugosostriata by the coarsely reticulated mesosoma, by the straight, not curved down propodeal spines, by the longer petiole, and by the strongly curved frontal carinae and distinctly narrower frons. E. orthospina most resembles E. electrina , but differs from the latter in the longer, not robust mesosoma, by the straight, not widened, pointed propodeal spines, and by the much longer petiole (PI 1.92 versus 1.27).

Figures

Fig. 1. Myrmicine ant Eocenomyrma orthospina sp. nov., the holotype worker, MZ 13434, from the Baltic Amber, late Eocene. A. Photograph in dorso−lateral view. B, C. Explanatory drawings, based on the original photographs; head, mesosoma and waist in dorso−lateral view (B), and mesosoma and petiole in lateral view (C).