Resumen:
Hylorina sylvatica (Anura: Batrachyidae) or emerald frog is a pond-breeding anuran, endemic to the austral temperate forests of Chile and Argentina. The distribution is narrowed in Argentina with few records and very limited biological information on the species in this area. In this study conducted during 2016, I investigated in details the reproductive parameters of the emerald frog in a semi-temporary wetland of Northwestern Patagonia, Argentina. During the Spring 2016, I visited the wetland weekly looking for chorus males, adults and amplexus. Also after amplexus were observed, I collected eggs and larvae among the aquatic vegetation using dep-netting sampling. Egg size and larval stage at hatch were registered. Three couples of emerald frog were captured and placed in enclosures inside the wetlands during the afternoon. I measured after 24 h the number of eggs laid in each enclosure and then males and females were released. Eggs were maintained in each enclosure until hatched. Chorus males were registered during the third week of October, and the first couples were observed on 26 October. The males were much smaller than the females, 53.32 mm ± 3 mm and 60.6 mm ± 0.9 mm respectively. The diameter of the eggs was 2.35 ± 0.45 mm. Hatched occurred between 10-14 days in the enclosures. This information contributes to knowledge of the biology of the emerald frog inhabit Patagonia Argentina and are the unique information available at to the moment for this species in the Nahuel Huapi National Park, were the species breed in different aquatic environments, from semi temporary wet meadows up to large permanent ponds.