Tadpoles of Boana geographica (Spix, 1824) (Anura: Hylidae) parasitized by Argulus sp. (Branchiura: Argulidae) in a Central Amazonia forest stream

Boana geographica is an arboreal and nocturnal anuran that reproduces throughout the year in the Amazonia. The tadpoles form large schools that occupy the upper layer of the water column, where they stay very close to each other. However, gregarious behavior can bring costs to organisms, such as increased parasite infestation risk.  In this work we report the occurrence of an undescribed species of Argulus parasitizing tadpoles of the hylid anuran B. geographica in Central Amazonia, present the parasitological indices (prevalence (P%), mean abundance (MA) and mean intensity (MI))  simple linear regressions to verify if the size and number of the ectoparasites were directly related to the size of the tadpoles.  The ectoparasite Argulus sp. was present in less than half of the tadpoles examined (P: 41%; MA: 0,61; MI: 1,48). There was no relation between the size of the tadpoles of B. geographica and the ectoparasite (r2 = 0.012, p = 0.396), but our results showed a positive relationship between the size of the host tadpole and the number of ectoparasites (r2 = 0.107, p = 0.018).  The interaction recorded here between the branchiuran ectoparasite Argulus sp. and tadpoles of the anuran B. geographica is surprising, since the tadpole life up to the metamorphosis is relatively short, and the parasite must have some survival strategy to deal with the host's exit from the aquatic environment.