A new freshwater species of Achlya from Tierra del Fuego Province, Argentina

Achlya ambispora sp. nov. occurring on litter (floating dead leaves and twi gs) in Las Cotorras stream, Tierra del Fuego Province, Argentina, is descri bed and illustrated and compared with similar species. The species produces principally androgynous and monoclinous, rarely diclinous antheridial bran ches; oogonial wall and oospores are distinctly yellowish at maturity and d iffer from other species in having also 1-6(-22) centric-subcentric oospore s, in oogonia sometimes apiculate, that are frequently intercalary or proli ferate in chains.