A bioprovince for the Barremian–Aptian charophytes of the Central Tethyan Archipelago

Abstract

A comprehensive bibliographic compilation of dozens of worldwide records of charophytes from the Barremian to early Aptian interval has been revisited aiming to gather the regional and global distribution data for the clavatoracean family. The compiled data were studied with the palaeontological statistics software PAST (PAleontological STatistics), using a cluster analysis. All analyses of the biogeographic data revealed a consistent separation of the Central Tethyan Archipelago (CTA) from other palaeogeographic areas, mainly the neighbouring Eurasian and American landmasses, based on the species richness of Family Clavatoraceae. The Central Tethyan Archipelago (CTA) is hence, proposed as a distinct bioprovince for Early Cretaceous charophytes, called the Clavatoracean Bioprovince, based on the abundance and especially the biodiversity of clavatoracean taxa (up to 26 taxa). Within the Archipelago, species distribution primarily shows a latitudinal pattern suggesting that the charophyte floras were subjected to climatic control. However, longitudinal relationships between areas in the eastern or western parts of the CTA were also found. In spite of these internal subdivisions of the Clavatoracean Bioprovince, the flux of populations between the islands must have been sufficiently strong to maintain taxonomic homogeneity within the archipelago throughout the time interval analysed. These biogeographic patterns are compared with those of non-marine ostracods for the same time interval, showing strong similarities and suggesting that they may be equivalent for other non-marine benthic organisms.