Description of the first sclerogibbid wasp (Hymenoptera: Sclerogibbidae) from Burmese (Myanmar) amber and its phylogenetic significance

Sclerogibbid wasps (Hymenoptera: Chrysidoidea: Sclerogibbidae) are the obligate parasitoids of webspinners (Embiidina) in extant fauna; fossil sclerogibbids are very rare, while fossil webspinners are more abundant. Burmese amber is the oldest Lagerstatte where both diverse webspinners and sclerogibbids are found. In this paper, Sclerogibba cretacica sp. nov. is described from Late Cretaceous Burmese (Myanmar) amber. The new species, assigned to the extant genus Sclerogibba Riggio & De Stefani-Perez, 1888, is the fourth known fossil species of Sclerogibbidae and the first known fossil male of this family. Moreover, this is the first described sclerogibbid wasp from Burmese amber and the first known fossil species of Sclerogibba. Sclerogibba cretacica is similar to extant sclerogibbid wasps with a closed discoidal cell from South-East Asia, but differs in the shape of the discoidal cell and small number of antennomeres (19 only). The phylogenetic significance of this species is discussed. Evolutionary trends in the antennal polymorphism of sclerogibbid wasps since the Cretaceous are outlined. The records of fossil webspinners, their ancestors (Alexrasniidae) and sclerogibbids suggest a Laurasian origin of Sclerogibbidae. The genus Protosclerogibba Olmi, Marletta, Guglielmino & Speranza, 2016 is synonymized with Herpetosphex Arnold, 1940 (Pompilidae) and Protosclerogibba australis Olmi, Marletta, Guglielmino & Speranza, 2016 is synonymized with Herpetosphex staphylinoides Arnold, 1940 (new synonyms).