Threatened fishes of the world : Diplomystes camposensis Arratia, 1987 (Diplomystidae)

Common name: Tollo (Spanish). Conservation status: Endangered in Chile (Glade 1989) and data deficient (IUCN 2007). Identification: Elongate diplomystid, maximum length 249 mm. Snout well developed slightly pointed or rounded in adults. Dorsal and pectoral fins with strong leading spine. Nostrils surrounded by large skin folds; a skin fold completely covering posterior nostril. Round epidermal papillae on barbel (Arratia 1987). Dorsal fin is more posteriorly placed than in D. chilensis (Molina 1782) and D. nahuelbutaensis Arratia, 1987. Distribution: Endemic to the Valdivia River basin in southern Chile, inhabiting high gradient parts of Cruces, Enco, San Pedro and Calle Calle rivers. Biology and ecology: Diplomystes camposensis prefers rithral areas with velocity <0.6 ms and boulder substrates, absent in potamal areas similar to D. nahuelbutaensis (Habit 2005). Uncommon in the San Pedro River: less than 5% total catch (personal observation). Absent in low order tributaries and in lakes. San Pedro River population exhibits low genetic variability (Hd=0.576, and π=0.0008), high gene flow (Nm=4.5), a maximum travel distance of nearly 3 km, and an average home range size of 50,000 m in adults over 20 cm total length (Habit et al. 2007). Populations upstream and downstream of Rinihue Lake and in the Cruces River show exclusive haplotypes. Feeds mainly on the decapod Aegla rostrata. Sexual maturity at 12 cm total length. In January larvae move from shallow riparian riffles to shallow pools with low current velocity. Threats: Habitat loss and fragmentation due to anticipated dams construction and introduced salmonids. Conservation actions: It is critical to protect areas with natural flow regime where the species is abundant to preserve the low genetic diversity. Remarks: Chilean Diplomystes species follow a North–South allopatric distribution. Diplomystes chilensis is apparently extinct (Arratia 1987) and D. nahuelbutaensis is considered endangered (Campos et al. 1998). Environ Biol Fish DOI 10.1007/s10641-008-9434-7