Spore morphology and wall ultrastructure of Anemia Swartz species (Anemiaceae) from Argentina

Spores of Anemia species that grow in Argentina are studied. The country corresponds to the southern limit in the distribution of the genus where nine species have been reported: Anemia australis, A. herzogii, A. myriophylla, A. phyllitidis var. phyllitidis, A. phyllitidis var. tweedieana, A. simplicior, A. tomentosa var. anthriscifolia, A. tomentosa var. tomentosa and A. wettsteinii. The material was examined using light microscope (LM), scanning electron microscope (SEM) and transmission electron microscope (TEM). The spores are trilete of 42–114μm in equatorial diameter and 34–106μm in polar diameter. The exospore is 1.2–7μm thick, two-layered; and two different ornamentations are observed: narrow and parallel ridges bearing baculae separated by wide and smooth grooves or parallel wide ridges with several ornamentations separated by narrow and smooth grooves. The perispore is 0.2–1.1μm thick, two-layered, and it may be plane or echinate with echina of variable sizes and shapes depending on the taxa analyzed. Perforations are also present on the perispore surface. The differences found in exospore and perispore morphology and ultrastructure could be valuable characters for systematic, phylogenetic and paleobotanical purposes. ► We studied the spores of nine species that grow in Argentina. ► Two different morphological types were observed. ► Variations may be found depending on the different kinds of perispore ornamentation. ► At ultrastructural level, there are differences in the exospore and perispore.