A new annual fish of the genus Austrolebias (Cyprinodontiformes: Rivulidae) from Rio Camaquã basin, Laguna dos Patos system, Brazilian Pampa.

A new species of Austrolebias is described from the middle course of the Rio Camaquã, Laguna dos Patos system, Rio Grande do Sul, Brazil. The new species belongs to the Austrolebias alexandri species group, which is distinguished from the remaining congeners by the presence of a dark gray pectoral fin with bright blue iridescence in males. The new species is distinguished from all remaining species of the A. alexandri species group by the following combination of characters: presence of well-defined bright blue bars on the flank in males, shorter caudal fin length in males and females, contact organs in the first three rays of the pectoral fin in males, one to two post-optic neuromasts (rarely three), basihyal width of 50% of the length, and basihyal cartilage about 50-60% of the basihyal length. The recognition of this new species belonging to the A. alexandri group endemic of the middle course of Rio Camaquã and the recent discovery of Austrolebias bagual in the same general region reinforces the claim of the middle Rio Camaquã basin as an area of endemism for annual fishes and as such, a priority area for conservation in southern Brazil.

First record of blackfin pearlfish Austrolebias nigripinnis (Regan, 1912 (Cyprinodontiformes, Cynolebiidae) from Brazil.

Austrolebias Costa is a genus of annual fish inhabiting temporary wetlands in the Chaco-Pampasic region of southern Brazil, Uruguay, Paraguay, Bolivia and Argentina (Costa, 2006, Nielsen & Pillet, 2015, Alonso et al., 2016). Currently, about 45 species of Austrolebias are known (Costa, 2006, Volcan et al., 2014, Nielsen & Pillet, 2015), and of these, 24 occur in Rio Grande do Sul, the southernmost state of Brazil, distributed across the Rio Uruguay basin and the Patos-Mirim lagoon system and adjacent coastal areas (Volcan et al., 2015).

Discovery of endangered annual killifish Austrolebias cheradophilus (Aplocheiloidei: Rivulidae) in Brazil, with comments on habitat, population structure and conservation status

Austrolebias genus comprises about 40 small annual killifishes endemic to South America and their highest diversity occurs in southern Brazil and Uruguay, especially in drainages of Patos-Mirim system. Austrolebias species are severely threatened with extinction because their life cycle and restricted ranges. Low dispersal ability and the extensive loss and fragmentation of freshwater wetlands contribute to this threat. Accurate information on the geographic distribution and ecology of the species, vital to plan conservation and management strategies, are scarce. In order to provide basic knowledge for annual fish conservation this paper reports the presence of Austrolebias cheradophilus and present data about its population structure (CPUA, size, sex ratio, length-weight relationships and condition factor) and conservation status in southern Brazil. The estimated CPUA of populations was 0.86 fish/m2. Standard length (SL) of males ranged between 32.14 and 49.17 mm and for females between 25.11 and 41.6 mm. There were no differences in SL between the sexes (t-test = - 1.678; P = 0.105), and Chi-squared test demonstrated marginal differences in proportions of sexes (2.25:1; χ2 = 3.846; P = 0.07). Allometric coefficient of the LWR was slightly hyperallometric (b = 3.08) and K of the specimens ranged from 1.84 to 2.42 (mean ± S.E. = 2.12 ± 0.04). Populations have low density and their biotopes are under critical threat, mainly due to suppression by agriculture, pastures for livestock and increase housing. The species is considered "Critically Endangered" in Brazil, furthermore is strongly recommended its inclusion on lists of endangered fauna and ensures the protection of their remaining habitats. O gênero Austrolebias compreende cerca de 40 espécies de peixes anuais endêmicos da América do Sul, cuja maior diversidade está concentrada no sul do Brasil e Uruguai, especialmente nas drenagens do sistema hidrográfico Patos-Mirim. A combinação de seu ciclo de vida peculiar com suas restritas distribuições, baixa capacidade de dispersão e ampla fragmentação das áreas úmidas fazem com que suas espécies sejam consideradas ameaçadas de extinção. Entretanto, informações sobre sua distribuição e ecologia são escassas. Visando fornecer informações básicas para a conservação, este estudo registra a presença de Austrolebias cheradophilus no sul do Brasil e apresenta dados sobre sua estrutura populacional (CPUA, tamanho, razão sexual, relação peso-comprimento e fator de condição) e estado de conservação. O CPUA total das populações foi de 0,86 peixe/m2. Não foram encontradas diferenças no tamanho padrão entre os sexos (t-test = - 1,678; P = 0,105) e o teste do Qui-quadrado apresentou um valor marginalmente significativo para a proporção dos sexos (2,25:1; χ2 = 3.846; P = 0.07). O coeficiente de "b" calculado com base na relação peso-comprimento indica um padrão de crescimento levemente alométrico positivo (b = 3,08). O fator de condição dos indivíduos variou entre 1,84 e 2,42 (média ± S.E. = 2,12 ± 0,04). As populações identificadas têm baixa densidade e estão sob ameaça crítica, principalmente devido à supressão do habitat pela agricultura, pecuária e aumento da urbanização. A espécie foi considerada "Criticamente Ameaçada", portanto recomenda-se sua inclusão em listas de fauna ameaçada e a urgente proteção dos seus habitats.