Shedding light on the Ophel biome: The Trans-Tethyan phylogeography of the sulfide shrimp Tethysbaena (Peracarida: Thermosbaenacea) in the Levant
Tethysbaena are small peracarid crustaceans found in extreme environments such as subterranean lakes and thermal springs, represented by endemic species found around the ancient Tethys, including the Mediterranean, Arabian Sea, Mid-East Atlantic, and the Caribbean Sea. Two Tethysbaena species are known from the Levant: T. relicta, inhabiting the Dead Sea-Jordan Rift Valley, and T. ophelicola, found in the Ayyalon cave complex in the Israeli coastal plain, both belonging to the same species-group based on morphological cladistics. Along the biospeleological research of the Levantine subterranean fauna, three biogeographic hypotheses determining their origins were proposed: (1) Pliocenic transgression, (2) Mid-late Miocenic transgression, and (3) The Ophel Paradigm, according to which these are inhabitants of a chemosynthetic biome as old as the Cambrian. We have used mtDNA COI gene and a molecular clock approach to establish the phylogeny and assess the divergence times of the Levantine Tethysbaena. Contrary to prior hypotheses, our results indicate a two-stage colonization pattern: a late Oligocene transgression, through a marine gulf extending from the Arabian Sea, leading to the colonization of T. relicta in the Dead Sea-Jordan Rift Valley, and a Miocene transgression in the emerging Mediterranean region, carrying T. ophelicola to the coastal plain of Israel.