|Publication Type:||Conference Paper|
|Year of Publication:||2016|
|Authors:||Sánchez-García, A, PeÑAlver, E, Delclós, X, Engel, MS|
|Conference Name:||The 7th International Conference on Fossil Insects, Arthropods and Amber|
|Publisher:||Siri Scientific Press|
|Conference Location:||National Museum of Scotland, Edinburgh|
Springtails (Hexapoda: Entognatha: Collembola) are a primitive lineage of conspicuous and ecologically varied hexapods, that comprise one of three groups in the clade Entognatha, and sister group to the hyper-diverse insects. The fossil record of springtails is scant and largely biased towards preservation in amber with its high fidelity. With a few exceptions, this bias generally restricts their geological occurrence to the Cretaceous and later, as it is from this period and onward that prolific ambers with bioinclusions are known. The extinct collembolan diversity from Early Cretaceous Spanish amber is reassessed owing to new and improved preparations of those previously reported specimens as well as the discovery of much new material. We have documented a total of more than 102 specimens preserved in Albian-aged amber from the Peñacerrada I outcrop, Burgos Province, northern Spain, which constitute the earliest amber fauna of springtails yet described. This review reveals a modest species diversity but one of considerable phylogenetic breadth in representation. All specimens identified belong to two orders: the elongate forms of the Entomobryomorpha and the more globular-bodied Symphypleona. Among the Entomobryomorpha, the family Isotomidae, with three new species described, appears numerically dominant regarding the total Spanish collembolan fauna. Although less abundant, a diverse fauna of Symphypleona, with five new genera and species described, was classified in at least three families (Sminthurididae, Katiannidae, Sminthuridae: Sphyrothecinae and Sminthuridae: Sminthurinae?). These discoveries include the first Mesozoic records of the Sminthurididae and Sphyrothecinae. Interestingly, many of the described forms are remarkably similar to their extant relatives, emphasizing the antiquity of the group as a whole as well as likely long-term niche conservatism. Based on morphological characters associated with specific habitat preferences and biological traits, some specialised reproductive strategies have been investigated for these fossil springtails.