Biogeography and relationship of the Gomphidae of Europe, North Africa, and the Middle East (Odonata)

摘要

Around 27 species of predominantly riverine Gomphidae occur in the vast region encompassing Europe as far as the Urals, the Maghreb, the Mediterranean Basin, and the Middle East up to the west side of the Indus valley, including Arabia, Iran, and Baluchistan. They are the remains of a pre-Pleistocene fauna that we estimate at twice the current number. We analyse the relationships, losses, and their causes at the molecular level and, not surprisingly, confirm the widely held opinion that the ice age is overwhelmingly responsible. Much extinction of European-West Asian and North American species took place in Beringia, presumably in an early phase of the glaciation. Recolonization between glacial stages can be evaluated for the final stage, the Wurm-Wisconsin glaciation. Differences in the orientation of mountain chains allowed more species to survive in North America than in Eurasia. They recolonized Canada, Europe, the Russian Far East, and Japan. From China, 16 additional gomphids are moving west through Siberia. Some reach the Ob valley but in others disjunctions persist. There are, for example, no Stylurus species in Pakistan, India, Bangladesh, and Thailand. Numerous preglacial survivors currently occur in Mediterranean and Middle Eastern refuges. Beside ice, aridity played a role in limiting the fauna. Oriental species advanced into the Middle East and Anatolia, but there was apparently never enough running water in Baluchistan to allow a large-scale movement of gomphids towards Europe. Rather to the contrary, the southeastern-most gomphid is Gomphus amseli, with type locality at the Heri Rud in Afghanistan, which forms a cline towards the west. Pakistan is even more impoverished in gomphids than Europe but is home to one small genus, Anormogomphus, that extends from northern India to eastern Anatolia. Africa also contributed little to the Palaearctic fauna. No Gomphus extends further south than the Maghreb, where several endemic species occur. Paragomphus sinaiticus is a desert species that does not occur south of the Sahara. The richest populations are situated in Oman. Two colonies coincide with the position of the shores of Lake Megachad, in the foothills of the Sahara-Sahel moun-tains of Air, Tibesti and Ennedi. Perhaps biotic factors like interspecies competition explain its range better than environmental factors. Around 8500 BP, the most recent riverine contact with the Nile via the Wadi Howar facilitated contact and crossing of the Red Sea, but Saharan populations could be older. Arabia was presumably invaded via the Sinai Peninsula, terra typica of the species.