Hydrolithon farinosum and Lithophyllum epiphyticum sp. nov. (Corallinaceae, Corallinales, Rhodophyta), Two Epiphytic Crustose Coralline Algae from the Abrolhos Archipelago, Brazil, Southwestern Atlantic

The aim of this study was to elucidate the taxonomy of the common but overlooked epiphytic coralline algae species from shallow reefs and seagrass meadows of the Abrolhos Archipelago, Brazil. Two thin (two vegetative cells thick) epiphytic coralline species were recorded: Lithophyllum epiphyticum sp. nov. and Hydrolithon farinosum. Molecular analysis from psbA genetic marker confirmed the position of L. epiphyticum into Lithophylloideae and revealed a phylogenetic relationship with an undescribed Lithophyllum from Italy. Thin thallus (2-3 cells thick) and cells lining the pore of tetrasporangial conceptacles protruding laterally occluding the canal, either partially or totally, are its main diagnostic characteristics. Hydrolithon farinosum is herein described in detail for Brazil, and its worldwide distribution is then discussed.