Biodiversity of earthworms in the levant

Today, 37 species, 16 genera, and five families (Acanthodrilidae, Criodrilidae, Lumbricidae, Ocnerodrilidae, and Megascolecidae) of earthworms are known to be present in the Levant. Out of all recorded species, 35-43% (13-16 species) have been directly or indirectly introduced by humans and 57-65% (21-24 species) seem to be autochthonous. Twelve to fourteen (50-67%) autochthonous species are endemic to the Levant (genera Dendrobaena, Healyella, Helodrilus, and Perelia). The autochthonous Levantine earthworm fauna is exclusively Palearctic, and species mainly show zoogeographic affinities to Anatolia-Caucasus and Europe. No observed earthworm endernism above the species level corresponds to the expected origin of earthworm fauna in the Levant between Rupelian (30-28 Mya) and Tortonian (11.5-6 Mya) (Oligocene-Miocene). In spite of the fact that speciation in earthworms might take millions of years, the observed new species isolated in the desert oases and along the Negev and Sinai Desert borders might change this perception if we can differentiate between relicts surviving the expansion of the Arabo-Syrian desert belt and subsequent speciation.