Austrolebias quirogai (Actinopterygii: Cyprinodontiformes: Rivulidae) in Brazil: occurrence, population parameters, habitat characteristics, and conservation status

Abstract

Background. The Neotropical genus Austrolebias is the most diverse of the Rivulidae family, with 22 species recorded in Brazil, with 21 found in the state of Rio Grande do Sul. Austrolebias quirogai Loureiro, Duarte et Zarucki, 2011 is an annual fish previously only found in Uruguay and there is currently no information about their ecology and life history. Here, we recorded A. quirogai for the first time in temporary wetlands in Brazil. Furthermore, we provide information about population parameters, life history traits, conservation status, and habitat characteristics. Materials and methods. We captured the fish with a D-shaped hand net in a sampling survey carried out in October 2012 in the Jaguarão-Chico River, Aceguá municipality, Brazil. We analysed density (CPUA), body size, length–weight relation (LWR), condition factor (K), and sex ratio. Results. We recorded a total of three populations of Austrolebias quirogai in the Jaguarão-Chico River. The CPUA was 0.33 fish · m–2. The sex ratio relation did not differ significantly and was 1.5 : 1 (M : F). The mean body size between sexes was not statistically different. The LWR of A. quirogai was W = 0.011TL3.23. The value of parameter b was significantly different from 3.0 for males and females, both sexes presenting positive allometric growth. The K for A. quirogai differed between sexes. Females had higher values than males. All populations of A. quirogai were found in ponds smaller than 1000 m² and were degraded by the activity of rice and soybean cultivation and overgrazing. We consider A. quirogai an endangered species in Brazil because of: its reduced area of occupancy, populations becoming severely fragmented, and suffering a continuous decrease in their area of occupancy and the quality of habitat. Conclusion. The observed results may be used to assist the development of management strategies and conservation of the species and its habitat. Moreover, they provide basic information for the evaluation of the conservation status of the species according to IUCN criteria and for the definition of priority areas for conservation in southern Brazil. Further studies should focus on the distribution, life history and ecology of the species to aid in their conservation.