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Rhinobatos percellens, Rhinobatos horkelli and Zapteryx brevirostris, known as guitarfish, are commonly found inshore and caught by trawl nets. Recently, these species have been suffering sharp population declines. One of the main impediments to the development of conservation plans is the lack of information related to each species catch. Gathering this information is made more difficult by the fishermen's practice of removing parts of the animals before landing, as well as the morphological similarities among the three species. To address these issues, this work presents multiplex-PCR protocols that were developed to distinguish among these species using their genetic characteristics.

The cranial muscles of cartilaginous fishes are the actuators of their feeding and respiratory mechanisms, and are thus of great interest regarding vertebrate evolutionary history and functional diversification. The following is a guide to the gross anatomy and function of these muscles in the three main lineages of cartilaginous fishes. Sharks are represented by the spiny dogfish Squalus acanthias , batoids by the southern guitarfish Rhinobatos percellens , and holocephalans by the spotted ratfish Hydrolagus colliei .

An adult female of the guitarfish Rhinobatos percellens with a total length of 550 mm was captured with a bottom trawl net on the southern coast of Brazil. This female bore five developing embryos, one of which had two heads and pectoral fins separated from the heads. This malformation is described here as the first instance for R. percellens .