Reedocalymenine trilobites from the Ordovician of central and eastern Asia, and a review of species assigned to Neseuretus

Recent cladistic analysis of the Reedocalymeninae necessitates taxonomic revision of the subfamily. Neseuretus Hicks, 1873, interpreted as both paraphyletic and polyphyletic, is rediagnosed. A list is provided of 65 different species or subspecies variously allocated to either Neseuretus or its junior synonym Synhomalonotus Pompeckj, 1898, with their current taxonomic status indicated. The new genus Aristocalymene is established to accommodate at least two morphologically aberrant species previously assigned to Neseuretus, and forming the dagger stem group of a clade also containing taxa previously assigned to Neseuretinus Dean, 1967, Sarrabesia Hammann and Leone, 1997 and Vietnamia Kobayashi, 1960. The type material of several Asian reedocalymenine taxa collected during the nineteenth and early twentieth centuries is redescribed. Neseuretinus birmanicus (Reed, 1906) is recognized as the senior synonym of N. turcicus Dean, 1967, but the taxonomic identity of South Chinese material assigned to the species remains difficult to determine. Redescription of Vietnamia douvillei (Mansuy, 1908) indicates that Sarrabesia is a junior synonym of Vietnamia. Calymene nivalis Salter, 1865, previously interpreted as a stratigraphically late representative of Neseuretus, is also reassigned to Vietnamia.