RESUMEN
Andes-to-Amazon river connectivity controls numerous natural and human systems in the greater Amazon. However, it is being rapidly altered by a wave of new hydropower development, the impacts of which have been previously underestimated. We document 142 dams existing or under construction and 160 proposed dams for rivers draining the Andean headwaters of the Amazon. Existing dams have fragmented the tributary networks of six of eight major Andean Amazon river basins. Proposed dams could result in significant losses in river connectivity in river mainstems of five of eight major systems-the Napo, Marañón, Ucayali, Beni, and Mamoré. With a newly reported 671 freshwater fish species inhabiting the Andean headwaters of the Amazon (>500 m), dams threaten previously unrecognized biodiversity, particularly among endemic and migratory species. Because Andean rivers contribute most of the sediment in the mainstem Amazon, losses in river connectivity translate to drastic alteration of river channel and floodplain geomorphology and associated ecosystem services.
RESUMEN
A new species of Chaetostoma was found in mountain tributaries of the río Marañon, Peru. The new species differs from all described congeners by having a tuft of odontodes, surrounded by naked skin, in the middle of each trunk lateral dermal plate, and in bearing more than 20 hypertrophied evertible odontodes on three cheek plates vs. evenly distributed odontodes on the whole surface of each dermal plate, and in bearing fewer than 20 hypertrophied evertible odontodes on three cheek plates in all other Chaetostoma species. The new species resembles two Cordylancistrus species in the presence of a tuft of odontodes in the middle of each trunk lateral dermal plate, but it exhibits a naked snout (vs. snout covered with plates in Cordylancistrus) and one uniquely derived character present in some species of Chaetostoma - a short, slender fourth branchiostegal ray.
Una distintiva especie de Chaetostoma fue descubierta en los tributarios de montaña del río Marañón, Perú. La nueva especie se diferencia de todas las otras especies de Chaetostoma descritas por tener un mechón de odontodes, rodeado por piel desnuda, en el medio de cada placa dermal lateral del tronco, y más de 20 odontodes hipertrofiados evertibles en tres placas de la mejilla, en contraste con los odontodes distribuidos de forma homogénea sobre toda la superficie de cada placa dermal lateral del tronco, y menos de 20 odontodes hipertrofiados evertibles en tres placas de la mejilla en las demás especies. La nueva especie se parece a dos especies de Cordylancistrus que exhiben un mechón de odontodes en el medio de cada placa dermal lateral del tronco, pero exhibe un hocico desnudo (vs. hocico cubierto por placas en Cordylancistrus) y un caracter derivado único de algunas especies de Chaetostoma - el cuarto radio branquiostego corto y delgado.
Asunto(s)
Animales , Ecosistema Andino/análisis , Bagres/clasificación , Especificidad de la EspecieRESUMEN
A new genus and species of armored catfish, Loraxichthys lexa, collected in 1955 by the Catherwood Foundation Peruvian-Amazon Expedition from the vicinity of Tingo María, Huánuco, is described herein. Loraxichthys is diagnosed by two uniquely derived characters: two to four robust evertible posterior cheek odontodes with hooked tips, longer than odontodes anterior to them but no more than twice their length; and skin folds on dorsal border along first pelvic-fin ray crenulated in mature males. Loraxichthys lexa, new species, is only known from clear water tributaries of the Río Huallaga in the vicinity of Tingo María. Additionally, notes on the morphology of the enigmatic species Lipopterichthys carrioni are included, and an artificial key for the genera Chaetostoma, Cordylancistrus, Dolichancistrus, Leptoancistrus, Lipopterichthys, and Loraxichthys is provided.
