Diet of critically endangered Valcheta frog, Pleurodema somuncurense (Anura: Leptodactylidae), in the Somuncura Plateau, Patagonia, Argentina

Abstract

In this work, we studied the diet of Pleurodema somuncurense and assessed selection patterns based on resource availability of terrestrial and aquatic prey items. We discuss potential implications for the current conservation status of this species and for management actions conducted with this species. Pleurodema somuncurense is endemic to the Valcheta Stream, Somuncura Plateau, Patagonia, Argentina. The conservation status of this frog is Critically Endangered, according to the IUCN red list. Our analysis frameworkwas based on assessing the diet composition in frogs through stomach flushing technique versus prey availability in the habitat. We also estimated the relative importance for each consumed prey. Of the 55 sampled individuals, we found identifiable contents in 47 stomachs.Our results showed that diet sample is composed of 179 prey items, most of them arthropods, including aquatic and terrestrial preys. The highest IRI was for Diptera (mostly from Family Tipulidae), Lepidoptera (Family Tineidae), Amphipoda (Family Hyalellidae), Araneae (mostly from Family Linyphiidae) and Isopoda (Family Armadillidiidae). The highest volumetric percentage was for Lepidoptera and Diptera. The use versus availability test showed active prey selection of P. somuncurense for Armadillidium isopods, and rejection of several prey items, particularly ants that were the most abundant terrestrial item. This dependence on terrestrial preys makes P. somuncurense susceptible to the ndirect effect on land use that affect prey availability, at least on aestival months when diet samples were taken.