Molecular phylogeny reveals independent origins of body scales in Entomobryidae (Hexapoda: Collembola).

Abstract

Entomobryidae is the largest family in Collembola but relationships within the family have never been subjected to rigorous phylogenetic analyses. Within the family, body scales are present in many species, and are fundamental in the classification at the subfamilial and tribal levels. A molecular phylogeny was reconstructed using the nuclear 18SrRNA and partial 28SrRNA and the mitochondrial 16SrRNA to examine the evolution of scales across Entomobryidae subfamilies. These datasets were analyzed separately and combined, with parsimony, likelihood and Bayesian algorithms. Monophyly of Orchesellinae was not recovered, and it was split into a scaled clade and an unscaled clade, contradicting to all recent taxonomic conceptions. The monophyly of Entomobryinae, Seirinae and Lepidocyrtinae is well supported however within Entomobryinae, the polyphyly of Entomobryini and Willowsiini implies that classification using the presence/absence of scales is not valid. Analyses of ancestral character state reconstruction in Entomobryidae indicate that the presence of body scales have evolved independently at least five times, with a loss of scales occurring independently at least twice. A revision of the family Entomobryidae on molecular and morphological basis is clearly needed.