The first Microcharon (Crustacea, Isopoda, Microparasellidae) from the Moroccan North Saharan Platform. Phylogeny, origin and palaeobiogeography

Abstract

The interstitial stygobites of the genus Microcharon (Crustacea, Isopoda, Microparasellidae) are highly diversified in Morocco, especially in the High Atlas. A new species from the North Saharan platform is described. Microcharon oubrahimae n. sp. is characterized by the original morphology of the first male pleopod which exhibits a concave inner margin of the distal part and a subdistal position of the armature. From a phylogenetic point of view, M. oubrahimae does not belong to the lineage which includes the Moroccan Atlasian species. In contrast, it belongs to the eastern- Mediterranean group of species. It is related to the species of the groupM. orghidani -M. bureschi -M. phlegetonis from Romania and Bulgaria. The two-step model of colonization and evolution provides an understanding of the origin and evolutionary history of this stygobiont. M. oubrahimae derived from marine ancestors that lived in the littoral interstitial waters of the marine gulfs which covered the Errachidia-Boudnib-Erfoud basin within the pre-African trench during the Turonian or more likely Early Senonian. These marine ancestors might have settled in fresh groundwater during the regressive phases of the Turonian embayment or more likely of the brief Coniacian-Santonian gulf.

Molecular phylogenetic relationships among some stygobitic cirolanid species (Crustacea, Isopoda)

“…The divergence time estimate suggests that the lineages diverged in relation to the marine transgression-regression phases and tectonic movements occurred in the Moroccan area during the Cretaceous and after the Atlas orogenesis (Eocene, 50-35 mya, Alvinerie et al, 1992). In the Cretaceous 90-65 mya in Morocco a deep Senonian gulf was present (Aït Boughrous et al, 2007) and it was generated by an atlantic big transgression which covered the Moroccan regions inhabited at present by the central-southern Typhlocirolana species (TIZ, GIN, SOU, ERR, LEP, ZAT, OUR). The molecular affinities among some Typhlocirolana taxa (M group, Figs 2-3) are probably the result of another marine regression event occured during the Tertiary period (Stoch, 2004).…”

Blurring the picture: introductions, invasions, extinctions – biogeography in a global world

“…The subject of Systematic Bio logy, in which we included topics such as biogeography, evolutionary biology, phylogenetics, and phylogeography, and Comparative Morphology nowadays make up about half of the papers published. Import papers in recent years dealt with the biogeography of well-known groups in much-studied regions such as amphibians in the West Palearctic (Arntzen et al, 2007;Veith et al, 2006) but also of lesser-known species from regions largely unstudied (isopods from the northern Sahara or pycnogonida from Socotra (Boughrous et al, 2007;Bartolino and Krapp, 2007). Biogeography and phylogeography have gained importance as research topics in zoology as is attested by the steady increase in both the number of journals devoted to this topic, such as the Journal of Biogeography (established in 1974), Ecography (1978), Global Ecology and Biogeography (1991) and Diversity and Distributions (1998), and the number of papers they publish (Fig.1).…”