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

Abstract

Protura is a poorly known class of Hexapoda represented by more than 800 species belonging to 77 genera worldwide. They are tiny soil organisms with low dispersal ability, mainly attributable to water and human-mediated transfer. The analysis of biogeography of Protura is hindered by the lack of knowledge on their natural history, systematics and distribution. In order to provide a starting point for future more detailed investigations, we reviewed the available literature on their geographic distribution, making a distinction between continental and insular areas. A general overview based on Wallace's biogeographic regionalization is outlined, highlighting a maximum of known richness and endemism at the genus level in the Palearctic region, and particularly within its eastern part. Some detailed examples of disjunct distribution and their interpretation based on vicariance or dispersal events are given.

Global distribution of microwhip scorpions (Arachnida: Palpigradi)

“…We showed that the distribution ranges of both soil and cave Eukoenenia species are very narrow even when compared to other subterranean species, and that range size does not significantly differ between the two guilds here considered. This suggests a limited dispersal potential for most species, as also empirically observed for other small‐sized soil‐ and cave‐dwelling specialists, such as proturans (Galli & Rellini, 2020) and diplurans (Sendra et al, 2020). An anecdotal example of this low dispersal ability can be found in the case of Eukoenenia maquinensis and E. sagarana , two cave‐adapted palpigrades from Brazil.…”

“…It is worth noting that continental-wide distribution has been observed in other soil-dwelling specialists; for example, these patterns can emerge as the result of continental drift paralleled by slow evolution, as in the amphi-Atlantic distributions of Protura (Galli & Rellini, 2020). In our case, the two most significant outliers are E.…”

“…This suggests a limited dispersal potential for most species, as also empirically observed for other small-sized soil-and cave-dwelling specialists, such as proturans (Galli & Rellini, 2020) and diplurans (Sendra et al, 2020). An anecdotal example of this low dispersal ability can be found in the case of Eukoenenia maquinensis and E. sagarana, two caveadapted palpigrades from Brazil.…”

“…This is a recurrent ecological pattern in subterranean systems and elsewhere, where communities are generally formed by several rare species and a few common ones (Bregović et al, 2019). It is worth noting that continental‐wide distribution has been observed in other soil‐dwelling specialists; for example, these patterns can emerge as the result of continental drift paralleled by slow evolution, as in the amphi‐Atlantic distributions of Protura (Galli & Rellini, 2020). In our case, the two most significant outliers are E. florenciae and E. mirabilis , two soil‐adapted species with parthenogenetic populations that have probably been moved beyond their historical ranges by humans (Harvey et al, 2006), for example through the soils used in greenhouses.…”

Is Acerentomon italicum Nosek, 1969 (Protura: Acerentomidae) a species complex?

“…This size difference was evidenced also in other species of Acerentomidae like Acerentulus shrubovychae Galli & Capurro, 2013 and Acerentulus tortii Galli et al, 2017. The existence of species complexes in Protura was already suggested by Fratello & Sabatini (1989) on the basis of differences between kariotypes of different Eosentomon transitorium Berlese, 1908a populations. A species-level diversifi cation can also be assumed for allopatric populations of some species that were likely separated by ancient vicariance events, as it is the case in the amphi-Atlantic Delamarentulus tristani (Silvestri, 1938) (see Galli & Rellini, 2020). Theoretically DNA barcoding could be an excellent tool to distinguish cryptic species, and in some cases it was used for that purpose since the early days (e.g.…”