Systematics on Viaphacops Maximova, 1972 from Bolivia and paleobiogeography of the subfamily Phacopinae Hawle & Corda, 1847 for the lower and middle Devonian, with a particular emphasis on the genus Paciphacops Maximova, 1972

The Subfamily Phacopinae Hawle & Corda, 1847 occurs stratigraphically from the Upper Ordovician to the end of the Devonian, spanning an approximately 85 million year interval. Its global distribution allowed extensive studies and a number of monographs have been published since the mid-1800s. The first chapter analyzes Viaphacops Maximova, 1972 which is one of the genera occurring in the Lower to Middle Devonian. New material from Bolivia enabled three new species (Viaphacops spinoedgecombei, V. newelli, and V. pirovanoi) and two in open nomenclature to be described here, in addition to the four described previously. With the examination of these species, the generic diagnosis of Viaphacops is revised. Cladistic analysis was conducted for the Bolivian Viaphacops together with 8 North American species to test their monophyletic relationship. It is found that two geographically separate groups Viaphacops, those from North America and those from the Malvinokaffric Realm in Bolivia, are non-monophyletic (Bolivian species either being a basal grade or nesting in otherwise North American clades), and that the difference in environmental settings for these regions did not seem to have affected the developmental constraints of the species. The second chapter treats the phacopid biogeography for the Lower and Middle Devonian, and follows the model of rugose coral biogeography of Pedder and Oliver (1990). More than 300 species belonging to 32 established genera were analyzed. Otsuka, Dice, and Jaccard Coefficient faunal similarity indices at the generic level were used for the 15 phacopid biogeographic units. Together with an area cladogram of Paciphacops, Maximova, 1972, strong connection was established between southeastern Australia and Bolivia-Argentina by the circumpolar circulation within southern Panthalassa. The position of Kazakhstan is still unresolved, however, both Otsuka Coefficients and the Paciphacops area cladogram show its connection with Australia and South America.