New odonatans (Odonata: Gomphaeschnidae; Synlestidae) from the Paleocene Paskapoo Formation: systematic and biogeographical implications

Abstract

The Paleocene Paskapoo Formation in Alberta, Canada offers a unique opportunity to gain insight into insect diversity at that time. This fossil insect-rich formation has yielded a variety of fossil arthropod specimens, including several Odonata wings related to the genus Alloaeschna Wighton & Wilson, 1986. Herein, we demonstrate that morphological characters previously used to separate three different species are instead the result of intraspecific variability. We reinforce this demonstration using two examples of high variability and plasticity in modern species of the family Aeshnidae. Accordingly, we reinterpreted the taxonomic position of Alloaeschna marklae Wighton & Wilson, 1986 syn. nov. and Alloaeschna quadrata Wighton & Wilson, 1986 syn. nov. as junior synonyms of Alloaeschna paskapooensis Wighton & Wilson, 1986. In addition, we describe the first occurrence of a Zygoptera in the Paskapoo Formation, namely Albertalestes paskapooensis gen. et sp. nov.(Synlestidae). Importantly, this new taxon is the first representative of the family found in North America. We also reconstructed the relationships within the Synlestidae under Bayesian inferences with a newly assembled matrix. Finally, we discuss the biogeography of the clade considering its fossil record using parsimony ancestral state reconstruction.