Fossil ants of the genus Gesomyrmex Mayr (Hymenoptera, Formicidae) from the Eocene of Europe and remarks on the evolution of arboreal ant communities Author Dlussky, Gennady M. Author Wappler, Torsten Author Wedmann, Sonja text Zootaxa 2009 2031 1 20 journal article 10.5281/zenodo.186261 f4bc44d8-5688-4500-839e-2449308f744c 1175-5326 186261 0919CF2B-DBC2-4504-B48A-8AD0D01695DB Key for determination of gynes of Gesomyrmex (gynes of extant species G. chaperi , G. howardi and G. kalshoveni unknown) 1. Anterior margin of clypeus straight or feebly concave ( Figs. 3 B, 5A, 5B).................................................................. 2 - Anterior margin of clypeus projects as rounded lobe ( Figs. 3 A, 4A–4C). Fossil species............................................ 4 2. Head more than 1.4 times longer than wide ( Figs. 5 A, 5B). Living species................................................................ 3 - Head about 1.2 times longer than wide ( Fig. 3 B). BL about 13 mm . Eckfeld, middle Eocene ...... G. flavescens sp. n. 3. Propodeum gradually rounded in side view. Eyes larger: head less than 3 times longer than maximum eye diameter. Posterior margin feebly concave ( Fig. 5 A). BL about 8.5 mm . Philippines . ............................ G. luzonensis (Wheeler) - Propodeum angulate in side view. Eyes smaller: head more than 3 times longer than maximum eye diameter. Poste- rior margin straight. ( Fig. 5 B). BL about 9.5 mm . Vietnam . ....................................................... G. tobiasi Dubovikoff 4. Head subrectangular, with feebly concave posterior margin, about 1.1 times longer than wide ( Fig. 4 B). BL 7–9 mm . Messel, middle Eocene .................................................................................................................. G. breviceps sp. nov. - Head more than 1.2 times longer than wide ................................................................................................................. 5 5. Head subtrapezoid, broader in its anterior part than in its posterior part, with gradually rounded posterior margin, without posterolateral corners. Eyes comparatively small: head 4.4 times longer than maximum eye diameter ( Fig. 4 C). Messel, middle Eocene. .......................................................................................................... G. curiosus sp. nov. - Head subrectangular with distinctive rounded posterolateral corners ( Figs. 2 A, 3A, 4A)........................................... 6 6. Eyes comparatively small: head 4.7 times longer than maximum eye diameter. Scape comparatively short: head 4.4 times longer than scape. Baltic, Bitterfeld, Rovno and Scandinavian ambers, late Eocene. .............. G. henschei Mayr - Head 2.5 to 3 times longer than maximum eye diameter, and 3 to 3.3 times longer than scape ( Figs. 3 A, 5A). ........ 7 7. Posterior margin distinctly concave ( Fig. 4 A). Head and most part of mesosoma yellowish brown, mandibles, central part of scutum, whole scutellum and median parts of gastral tergites dark brown. BL 4.8 mm . Messel, middle Eocene ............................................................................................................................................... G. pulcher sp. nov. - Posterior margin feebly convex (Fig. 8A. Whole body black. BL 9–10 mm . Eckfeld, middle Eocene. ...................... ................................................................................................................................................... G. germanicus sp. nov.