Long-term stasis in a diverse fauna of Early Cretaceous springtails (Collembola: Symphypleona)

摘要

Springtails (Hexapoda: Entognatha: Collembola) extend into at least the Early Devonian, but have a meagre record as fossils until the latter part of the Mesozoic. Here, we document a diverse fauna of springtails in the order Symphypleona from amber recovered at the Penacerrada I locality, Moraza, northern Spain, and from the Late Albian Utrillas Group in the Basque-Cantabrian Basin. The fauna includes representatives of all of the principal suborders and infraorders, and most superfamilies, of the Symphypleona. This revision of the fauna includes the discovery and description of five new genera and species scattered across the phylogenetic diversity of the clade: Pseudosminthurides stoechus gen. et sp. nov. (Sminthurididae), Cretokatianna bucculenta gen. et sp. nov. (Katiannidae), Sphyrotheciscus senectus gen. et sp. nov. (Sminthuridae: Sphyrothecinae), Archeallacma dolichopoda gen. et sp. nov. (Sminthuridae: Sminthurinae?) and the enigmatic Katiannasminthurus xenopygus gen. et sp. nov. (Sminthuridae? incertae sedis). This is the earliest amber fauna of springtails yet described, and highlights the remarkably modern character of the group even during the early stages of the Cretaceous.