CONICET | Buscador de Institutos y Recursos Humanos

Background and aims: Paspalum lilloi (Poaceae) is a diploid species, endemic ofIguazú Waterfalls and nearby areas. The reproductive biology and current geographicaldistribution of this species are poorly known. The aims of this work were to determinethe genetic system and to delimit the endemism area and conservation status of thespecies.M&M: The genetic system was determined by cytoembryological analysis of ovules,viability and in vivo germination of pollen grains, pollen-pistils compatibility, fertility andflow cytometry of single seeds. Herbarium specimens and our collection sites delimitedthe geographical distribution.Results: Meiotic embryo sacs of Polygonum type were observed in all analyzed ovules.No evidence of apomixis was detected. The mean pollen viability and in vivo pollengermination was 95.2% and 41.8%, respectively. The pollen tube growth in theselfed stigmas was 59.2 ± 6.39 μm / 3h. Seed set in self-pollination was 93.6 % anddecreased to 52.7 % when there was heterospecific pollen available. Seeds analyzedby flow cytometric seed screen showed an embryo: endosperm ratio 2:3 indicateda sexual origin. Paspalum lilloi is a reophile and rupicolous species, specialized infast-moving waters of waterfalls and it is a critically endangered endemism of IguazuWaterfalls, in South America.Conclusions: P. lilloi is sexual, self-compatible and self-fertile species. Has a highlyspecialized habitat, which conservation will be a key step to avoid its extinction.

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