Permalink : http://hdl.handle.net/2115/53635

All fossil psocid species ('Psocoptera', i. e. free living, mostly bark-dwelling members of the insect order Psocodea) known from Cretaceous amber are listed and their systematic placement is discussed. This critical evaluation of published data resulted in a list of 32 species assignable to 27 genera and 11 families. Each genus could be assigned to one of the three suborders Trogiomorpha, Troctomorpha and Psocomorpha, but five genera could not clearly be assigned to a family. No extant genus is represented in Cretaceous amber. Several systematic misallocations, a few at subordinal level, have been identified. Suborder transfers are proposed for the genera Paramesopsocus, Arcantipsocus and Libanopsyllipsocus; an infraorder transfer within Troctomorpha is proposed for Globopsacus. The extant troctomorph family Pachytroctidae is recorded for the first time from the Cretaceous. Two family-group names of Psocomorpha (Paramesopsocidae and Arcantipsocidae), based on extinct taxa, are considered as synonyms of two extant families of Troctomorpha (Electrentomidae and Amphientomidae respectively). The extant family Lachesillidae is the only family of Psocomorpha represented in Cretaceous amber. 53% of the species from Cretaceous amber belong to the Trogiomorpha, representing the basal clade of Psocoptera; 41% belong to Troctomorpha and only 6% to Psocomorpha, while the latter comprises 69% of the species known from Baltic amber (Eocene) and 82% of the extant species. The presence of the family Lachesillidae shows that the deepest divergences of the psocomorphan phylogeny date back at least to the Cretaceous, but the main radiation of Psocomorpha at generic or species level probably happened in the Cenozoic. This critical review of published information about the oldest known fossils clearly assignable to the order Psocodea (as this group is defined by taxonomists working on the extant fauna) aims to refine the data which could provide some fossil evidence for calibration of molecular trees in future research on the phylogeny of paraneopteran insects.