Description (gyne) Gerontoformica sp.: JZC Bu 1821 (Fig S 3 G,I) A well-preserved but partially obscured specimen. The dealate ant is suspended in a resin flow among hundreds of bubbles, preventing some lateral views. The piece is 2.5 x 1.4 x 0.9 cm, trimmed flat on one surface to provide a clear ventral view of the head and body. Head length 1.43; head width 1.38; eye length 0.50; mesosomal length 2.37; petiole length 0.60; gaster length 2.61; antenna: scape 0.57; pedicel 0.31, flagellomere I+II+III +IV obscured, V 0.32, VI 0.31, VII 0.25, VIII 0.23, IX 0.28, X 0.43. Head broadly rounded square, slightly narrowing anteriorly. Mandibles bidentate, anterior margin of clypeus with peg-like denticles, difficult to enumerate (> 12), characteristic of other Gerontoformica taxa. Antennal sockets posterior to clypeal margin, surrounded by slightly depressed area relative to medially elevated cuticle between antennae. Frontal carina spiraling out from just lateral to inner margin of antennal socket to anterior margin of eye, as in G. orientalis and G. spiralis. Ocelli present. Pronotum with anteriorly expanded neck: propleuron visible in lateral view. Mesoscutum highly developed, flattened dorsally; transscutal fissure very faint; scutellum raised dorsally; wing stubs clearly visible. Metapleural gland opening gaping, projecting posteriorly. Propodeum reduced, sloping dramatically. Protibial spur bifurcating near apex, pectinate between these two apicies; mesotibia and metatibia each with two approximately equal length spurs, one pectinate; trochantellus present, pretarsal claw with subapical tooth. Petiole pedunculate, apparently attached somewhat broadly although attachment point mostly obscured by a fissure. Gaster segment I with slight ventral projection; gastral segments not terg-sternally fused, largely obscured. Sting present.

Published as part of Phillip Barden & David A. Grimaldi, 2016, Adaptive Radiation in Socially Advanced Stem-Group Ants from the Cretaceous, pp. 515-521 in Current Biology 26 on page 540, DOI: 10.1016/j.cub.2015.12.060, http://zenodo.org/record/269536