Intertidal Species of Gelidium from the Temperate Coast of Argentina

Abstract

The Gelidiales comprises economically valuable species of marine red algae that are found globally, in cold, temperate, and warm waters. Although there is much known about the species diversity and distribution of this order, it remains underexplored on the temperate coast of the Southwestern Atlantic Ocean. This study aimed to update current knowledge about the intertidal Gelidiaceae found on the temperate coast of Argentina using a combination of rbcL data and morpho-anatomical studies and to evaluate the morphological variability among species related to habitat characteristics. Three morphotypes were found at the six localities surveyed; two were identified as different morphologies of Gelidium crinale and one was identified as Gelidium carolinianum. Populations of both species were widespread and coexisted extensively from 37° S to 40° S along the Argentinean coast. G. carolinianum is newly reported in the Southern Hemisphere, indicating it has a disjunct distribution that includes the North Atlantic and Mediterranean as well. Molecular data confirmed previous reports of G. crinale in Argentina, a species that exhibited broad morphological variability among sites. The development of both spermatangia and carpogonia on the same fertile gametophyte thalli in G. crinale and G. carolinianum was described for the first time and demonstrated that they are monoecious. These findings shed light on the diversity and biogeography of Gelidiales from temperate South America.