Record of reproductive structures of three species of the Order Bryopsidales (Chlorophyta, Ulvophyceae) from the Mexican Caribbean

Background and Aims: Despite the ecological importance of Bryopsidales species in marine tropical ecosystems, little is known about the reproductive aspects of the Mexican Caribbean species. The study of the reproductive structures contributes useful elements to the understanding of aspects of the life cycle, taxonomy and phylogeny. The main objective is to describe and illustrate the reproductive structures of Avrainvillea digitata, A. nigricans f. floridana and Halimeda incrassata. Methods: Fertile thalli were collected from four sample sites in the Biosphere Reserve of Sian Ka’ an, Quintana Roo, Mexico. Descriptions of the morphology and anatomy of the thalli, as well as of the structure and size of the reproductive structures were elaborated. Key results: In A. digitata, sporangia are claviform whereas they are ellipsoidal in A. nigricans f. floridana. In both species of Avrainvillea the structures develop as projections of the siphons from the thalli apical portion. In H. incrassata, gametophores arise from the terciary utricle and carry eight to 10 piriform gametangia. Conclusions: This work represents the first morphological description of reproductive structures of Avrainvillea digitata, A. nigricans f. floridana and Halimeda incrassata from the Mexican Caribbean.