Unexpected case of cancrivory in a lotic tropical ecosystem: First record of predation of Strengeriana maniformis by the frog Rheobates palmatus

Abstract

The organic matter in the form of detrital material from the riverside of the flowing waters constitutes the most important contribution of nutrients and energy received by the lotic ecosystems. The detritivore invertebrates of lotic ecosystems are the first to consume the bigger organic matter and disintegrate it into fine particles. If the amphibians exert predatory pressure over detritivore invertebrates, they could be indirectly influencing the disintegration of organic matter in flowing waters ecosystems being this a fundamental ecological process in such ecosystem. The aim of this work is to describe the first predation event over a detritivore freshwater crab Strengeriana maniformis by the Colombian endemic frog Rheobates palmatus. During herpetological surveys conducted on August 10, 2019 at a creek known locally as Soto, Norcasia municipality, Caldas department, at the eastern hillside of the Central mountain range, Colombia an adult of R. palmatus was caught at 21:50 h. The individual was located on the ground at 2 m from the edge of a creek which is surrounded by a fragment of tropical rainforest. The stomach content of the individual was sampled using the stomach-flushing technique, and a male individual of the crab S. maniformis was recorded inside it. Ecologically, this new trophic link described in this work makes a small but important contribution to the knowledge of the natural history of both taxa. But, also reveal that the amphibians could exert predatory pressure over detritivore invertebrates of lotic ecosystems as freshwater crabs, which have a fundamental ecological process in such an ecosystem by the disintegration of organic matter.