Stephanidae

Family of wasps

The Stephanidae, sometimes called crown wasps, are a family of parasitoid wasps. They are the only living members of the superfamily Stephanoidea. Stephanidae has at least 345 living species in 11 genera. The family is considered cosmopolitan in distribution, with the highest species concentrations in subtropical and moderate climate zones. Only stephanids and the similarly old Hymenoptera family Orussidae have ocellar coronae, and it is uncertain if they developed the structure separately or if a common ancestor of both developed it and it was then lost in all but the two families. Weakly developed grooves starting at the base of the antennae and extending past the eyes to the back of the head capsule are present. This feature is seen more developed in hymenopteran families in which the adults emerge from pupal chambers in wood.

The family is noted to be the most basal group of hymenopterans in the suborder Apocrita. They are the only living group left over from the early diversification of Apocrita. In general, the family is considered rare, with close to 95% of the species known to have been described from single specimens. Until the early 1800s, members of Stephanidae were grouped into the parasitic wasp superfamily Ichneumonoidea based on the superficial resemblance between some members of the two groups. William Elford Leach suggested a new family grouping for the stephanids in the 1815 edition of Edinburgh Encyclopædia. Other early member of the family is the monotypic genus Archaeostephanus, which is known from a single species Archaeostephanus corae found in the late Cretaceous New Jersey amber and first described in 2004. The first species to be described from the fossil record was Protostephanus ashmeadi, which was first published in 1906 by paleoentomologist Theodore Dru Alison Cockerell. The specimen is also the youngest fossil found, dating from the Late Eocene Florissant Formation. All other extinct species in the family are known from fossils preserved in Baltic amber. Based on the fossil record of the family, Li et al. (2017) infer that the family originated during the Late Jurassic or Early Cretaceous. Taxonomy of the family as outlined by Michael S. Engel and Jaime Ortega Blanco in 2011: