Recent introduction of Gracilaria parvispora (Gracilariales, Rhodophyta) in Baja California, Mexico

Gracilaria parvispora is reported for the first time as an invasive species in northwestern Mexico based on morphological, anatomical and molecular data. The species is widely distributed in the region, where it colonizes sandy and rocky habitats from intertidal areas down to a depth of 1.5 m. The morphological and anatomical data from the Mexican specimens matched the circumscription of the species in Hawaiian waters. Two molecular markers (rbcL and cox1) showed that the Mexican populations were closer to the Hawaiian populations than the Korean populations, which may relate to a similarity in seawater temperatures between Hawaii and Baja California. Gracilaria parvispora formed extensive mats together with Gracilaria vermiculophylla. It was found in stomach samples from a green turtle (Chelonia mydas) in the coastal lagoons of Baja California Sur. The ecological impacts of the two alien Gracialria species on other native species and communities have yet to be determined. This is the first demonstration of a second invasive Gracilaria species, following the introduction of G. vermiculophylla into the northwestern Mexico region.