Going Deeper into High and Low Phylogenetic Relationships of Protura

Abstract

Proturans are small, wingless, soil-dwelling arthropods, generally associated with the early diversification of Hexapoda. Their bizarre morphology, together with conflicting results of molecular studies, has nevertheless made their classification ambiguous. Furthermore, their limited dispersal capability (due to the primarily absence of wings) and their euedaphic lifestyle have greatly complicated species-level identification. Mitochondrial and nuclear markers have been applied herein to investigate and summarize proturan systematics at different hierarchical levels. Two new mitochondrial genomes are described and included in a phylum-level phylogenetic analysis, but the position of Protura could not be resolved with confidence due to an accelerated rate of substitution and extensive gene rearrangements. Mitochondrial and nuclear loci were also applied in order to revise the intra-class systematics, recovering three proturan orders and most of the families/subfamilies included as monophyletic, with the exception of the subfamily Acerentominae. At the species level, most morphologically described species were confirmed using molecular markers, with some exceptions, and the advantages of including nuclear, as well as mitochondrial, markers and morphology are discussed. At all levels, an enlarged taxon sampling and the integration of data from different sources may be of significant help in solving open questions that still persist on the evolutionary history of Protura.

The geographic distribution of Protura (Arthropoda: Hexapoda): a review

“…First of all, systematics of this group is still unclear and the contribution to it of genetics is currently very limited. A fact on which there is a consensus is that the orders Sinentomata and Eosentomata (François, 2003;Dell'Ampio et al, 2011;Resh et al, 2014;Carapelli et al, 2019) form the sister group of Acerentomata. Among Eosentomata, moreover, Carapelli et al (2019) pointed out that the Oriental genus Zhongguohentomon (subfam.…”

“…We can, therefore, think to the ancestor of this order close to Isoentominae. According to their morphological characters (see Galli et al, 2018;Carapelli et al, 2019), Eastern Palearctic and Oriental Antelientomidae belong to a more recent line originating from the one that culminates in Eosentomidae. Acerentomata are probably closer to Sinentomata than to Eosentomata since they are more similar for some morphological characters (see François, 2003;Galli et al, 2018).…”

“…Acerentomata are probably closer to Sinentomata than to Eosentomata since they are more similar for some morphological characters (see François, 2003;Galli et al, 2018). Hesperentomidae and Protentomidae form the sister group of the other Acerentomata (François, 2003;Dell'Ampio et al, 2011;Carapelli et al, 2019). On the relationships among the Acerentomidae subfamilies, Carapelli et al (2019) highlighted that Berberentulinae and Acerentominae are sister groups.…”

“…Hesperentomidae and Protentomidae form the sister group of the other Acerentomata (François, 2003;Dell'Ampio et al, 2011;Carapelli et al, 2019). On the relationships among the Acerentomidae subfamilies, Carapelli et al (2019) highlighted that Berberentulinae and Acerentominae are sister groups. The latter are probably paraphyletic: Acerellinae and Nipponentominae should be included in them.…”

Protura in Arctic Regions, with Description of Mastodonentomon n. gen. (Acerentomidae, Nipponentominae) and a Key to Known Arctic Taxa

“…Originally regarded as an order belonging to the class Insecta [2], Protura was later placed among the basal hexapod taxa as the sister taxon to either Collembola or Diplura. Their phylogenetic position, however, is still a point of controversy [1,3]. Since their first description in 1907 [2], over 800 valid species belonging to three orders, seven families, and…”