TIMING OF THE EVOLUTIONARY HISTORY OF CORALLINACEAE (CORALLINALES, RHODOPHYTA)

The temporal dimension of the most recent Corallinaceae (order Corallinales) phylogeny was presented here, based on first occurrence time estimates from the fossil record. Calibration of the molecular clock of the genetic marker SSU entailed a separation of Corallinales from Hapalidiales in the Albian (Early Cretaceous similar to 105mya). Neither thecalibration nor the fossil record resolved the succession of appearance of the first three emerging subfamilies: Mastophoroideae, Corallinoideae, and Neogoniolithoideae. The development of the tetra/bisporangial conceptacle roofs by filaments surrounding and interspersed among the sporangial initials was an evolutionary novelty emerging at the Cretaceous-Paleogene boundary (similar to 66mya). This novelty was shared by the subfamilies Hydrolithoideae, Metagoniolithoideae, and Lithophylloideae, which diverged in the early Paleogene. Subclades within the Metagoniolithoideae and Lithophylloideae diversified in the late Oligocene-middle Miocene (similar to 28-12mya). The most common reef corallinaceans (Hydrolithon, Porolithon, Harveylithon, Pneophyllum conicum, and subclades within Lithophylloideae) appeared in this interval in the Indo-Australian Archipelago.