Material examined: male holotype, PIN no. 3901 / 132 from Eastern Siberia, Magadan Region, Obeschchayushchiyi fossil site, Upper Cretaceous (Cenomanian), Ola Formation (90–95 mybp). FEMALE: unknown.
MALE (Fig. 9): length 4.5 mm; length of the main regions: head: 0.56 mm; mesosoma: 3.94 mm; prothorax: 0.25 mm; mesothorax + metathorax + propodeum: 3.69 mm; gaster: 2.50 mm. Antennae missing. Head only visible from lateral side. Eyes large (eyes length shorter than head in lateral view (0.37: 0.56)). Temples very reduced. Occiput not visible. Palpi not visible. Mesosoma normal (as in the extant males of Gonatopus). Forewing hyaline, with three basal cells completely enclosed by pigmented veins. Marginal cell open (distal extremity of stigmal vein reaching the wing margin, but narrower that rest of vein). Pterostigma very narrow, with the following length/breadth ratio: 11: 2.5. Petiole absent. Legs only partly visible. Tibial spurs not visible.
Remarks: Gonatopus cretacicus n. sp. is tentatively attributed to Gonatopus Ljungh, 1810, though it is only visible from lateral side. However, the head shape, pterostigma shape, forewing venation and general shape of the body are typical of Gonatopus males. No further fossil species of Gonatopus are known. N. Ponomarenko (1981) described Laberius antiquus from Taimyr amber. It was included in the genus Laberius Kieffer, 1914, that now is considered junior synonym of Gonatopus Ljungh. However, this species is now attributed to Dryinus Latreille, 1804 (Olmi, 1984; Olmi & Bechly, 2001).