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Evolution of habitat usage and body size in cynopoeciline killifishes. (A) Evolution of habitat usage, including open, savannah-like vegetation and dense forest, and (B) biogeographic reconstruction based on four areas of endemism for cynopoecilines, inferred from the Bayesian model for ancestral area reconstruction implemented in RASP 3.02, using the model F8l with gamma distribution, and maximum number of ancestral areas = 1 and 2, respectively; photographs above represent a typical costal open vegetation habitat and a dense rain forest habitat,
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Cynopoecilines comprise a diversified clade of small killifishes occurring in the Atlantic Forest, one of the most endangered biodiversity hotspots in the world. They are found in temporary pools of savannah-like and dense forest habitats, and most of them are highly threatened with extinction if not already extinct. The greatest gap in our knowled...
Citations
... Among them, the Cyprinodontiform seasonal killifishes belonging to the Rivulidae family are particularly vulnerable due to their small body size, narrow geographic ranges, and reliance on seasonal aquatic habitats that are highly impacted by human activities. (Costa 2016;Alonso et al. 2018). In fact, nearly 48% of Cyprinodontiform killifish species in the Neotropical region are categorized as threatened (Tagliacollo et al. 2021). ...
We describe Argolebias adrianae, a new species of killifish from a small temporary wetland in the Paraná Forest ecoregion with no regular or predictable temporal pattern of water availability. This habitat is in the Lower Iguazú River Basin, known for its high fish endemism, but until now, only two species of Rivulidae were reported from it, but from the Araucarian Forest ecoregion. The genus Argolebias was previously only known from the lower portions of the Paraguay, Paraná, and Uruguay basins and middle Paraná. The new species is distinguished from all congeners by its unique coloration, which includes a conspicuously dark grey anterior third portion of the dorsal fin and the absence of iridescent spots on the basal half of the pectoral fin in live adult males, as well as dark grey spots on the anterocentral portion of the flanks of females. Our phylogenetic analysis shows A. adrianae to be closely related to Argolebias guarani from the adjacent Middle Paraná basin. We also provide data on the ecology, ontogeny of coloration, and chorion ornamentation of this species. Our findings have important implications for understanding the biogeography, ecology, and evolution of mechanisms that enable organisms to thrive in highly stochastic environments like this one.
... The Atlantic Forest of south-eastern Brazil encompasses one of the most species-rich biota in the world, with a high diversity of plants and animals (Myers et al. 2000). Although the greatest part of the original Atlantic Forest was extirpated in the last three centuries and consequently several endemic species became endangered or even extinct, new species are still being recognised in recent years (Tabarelli et al. 2005;Costa 2016a). Aplocheilid killifishes are represented in the Atlantic Forest by 14 genera and over 45 valid species (Costa 2009(Costa , 2014(Costa , 2016bAmorim 2013, 2014;, of which six genera and 18 species belong to the tribe Cynopoecilini (Costa 2008(Costa , 2016bFerrer et al. 2014). ...
... The greatest species diversity of cynopoecilines is concentrated in the coastal plains of Rio de Janeiro State, south-eastern Brazil (i.e., eight valid endemic species in three genera, of which two genera are endemic), with most taxa consisting of miniature species not surpassing 25 mm standard length (SL) and exhibiting high diversification of morphological traits (Costa 2008(Costa , 2016a. Different kinds of vegetation formations sheltering distinct seasonal killifish habitats are present in this region, including temporary pools in seasonally dry forests and coastal restingas, and seasonal swamps in dense moist forests (Costa 1995(Costa , 2009(Costa , 2016a. ...
... The greatest species diversity of cynopoecilines is concentrated in the coastal plains of Rio de Janeiro State, south-eastern Brazil (i.e., eight valid endemic species in three genera, of which two genera are endemic), with most taxa consisting of miniature species not surpassing 25 mm standard length (SL) and exhibiting high diversification of morphological traits (Costa 2008(Costa , 2016a. Different kinds of vegetation formations sheltering distinct seasonal killifish habitats are present in this region, including temporary pools in seasonally dry forests and coastal restingas, and seasonal swamps in dense moist forests (Costa 1995(Costa , 2009(Costa , 2016a. This region also contains the greatest occurrence of cynopoeciline species threatened with extinction in South America, some of them critically endangered or presumably extinct (Costa 2002b(Costa , 2009(Costa , 2012, with most taxa poorly represented in ichthyological collections and not collected in recent years (Costa 2016a). ...
Specimens found between 1985 and 1988 in the Magé River Basin, south-eastern Brazil were misidentified as L. splendens. The recent rediscovery of other specimens in the Estrela River Basin near the type locality of L. splendens has clarified the species' concept, making it possible to recognise the Magé River Basin specimens as a new species. The new species is herein described as Leptopanchax sanguineussp. nov. and is distinguished from all other cynopoecilines by a unique colour pattern in males, including red bars with sinuous margins. It was collected in a well-preserved, temporary shallow swampy area within dense moist forest, but since 1990 the species has not been found again. Leptopanchax sanguineussp. nov. is one of three species of cynopoeciline killifishes living in lowland moist forests of the coastal plains of Rio de Janeiro State, where the greatest diversity of endemic cynopoecilines is concentrated. Each of these species has been recorded a single time in the last 30 years, a surprisingly low record attributable to intense deforestation during the last several decades resulting in small fragmented lowland moist forests of today. This study indicates that seasonal killifishes adapted to uniquely live in this kind of habitat should be regarded with special concern in studies evaluating conservation priorities.
... Cynopoecilus é endêmico de uma vasta área do sul do Brasil e nordeste do Uruguai, sendo a maioria das espécies encontradas em formações abertas de pastagem, mas algumas vezes são encontradas em poças nas bordas de florestas costeiras. Cynopoecilus notabilis é uma exceção, pois habita poças rasas dentro de densa floresta estacional semidecidual (Ferrer et al., 2014;Costa, 2016). Identificação. ...
Cynopoecilus, assim como as espécies de Campellolebias, possuem modificações nos primeiros raios da nadadeira anal dos machos, que possivelmente estão relacionadas à inseminação (Costa et al., 2016). Cynopoecilus é endêmico de uma vasta área do sul do Brasil e nordeste do Uruguai, sendo a maioria das espécies encontradas em formações abertas de pastagem, mas algumas vezes são encontradas em poças nas bordas de florestas costeiras.
Cynopoecilus notabilis é uma exceção, pois habita poças rasas
dentro de densa floresta estacional semidecidual (Ferrer et al.,
2014; Costa, 2016).
Identificação. Cynopo
... Cynopoecilini. Costa (2016a) proposed seven synapomorphies for Cynopoecilini, based on a previous total combined (morphological and mitochondrial) phylogenetic analysis (Costa, 2016b). Five of them already described in Costa (2008a): 1. vomer teeth absent; 2. ventral process of angulo-articular vestigial or absent; 3. posterior process of quadrate wide (Fig. 1d); 4. symplectic elongate (Fig. 1d), 5. supraorbital scales absent (according to Ferrer et al., 2014, reversed in some Cynopoecilus Reagan species); 6. distinctive postero-ventral process on autopalatine; and 7. E-scales not overlapped "(reversed in Cynopoecilus feltrini)". ...
The family Rivulidae is the fourth most diverse clade of Neotropical fishes. Together with some genera of the related African family Nothobranchiidae, many rivulids exhibit a characteristic annual life cycle, with diapausing eggs and delayed embryonic development, which allows them to survive in the challenging seasonal ponds that they inhabit. Rivulidae also includes two species known as the only the self-fertilizing vertebrates and some species with internal fertilization. The first goal of this article is to review the systematics of the family considering phylogenetic relationships and synapomorphies of subfamilial clades, thus unifying information that is dispersed throughout the literature. From this revision, it is clear that phylogenetic relationships within Rivulidae are poorly resolved, especially in one of the large clades that compose it, the subfamily Rivulinae, where conflicting hypotheses of relationships of non-annual and annual genera are evident. The second goal of this work is to present an updated phylogenetic hypothesis (based on mitochondrial, nuclear, and morphological information) for one of the most speciose genus of Rivulidae, Austrolebias. Our results confirm the monophyly of the genus and of some subgeneric clades already diagnosed, but propose new relationships among them and their species composition, particularly in the subgenus Acrolebias.
... An exception is the killifish suborder Aplocheiloidei, with included clades having their distribution associated with tropical and subtropical biomes of South America and Africa (e.g., Amiet, 1987;Costa, 1995;Dorn et al., 2014). Consequently, species groups often recognised as genera are geographically restricted to specific biomes where their habitats (i.e., shallow swamps and temporary pools) are situated (e.g., Amiet, 1987;Costa, 2016a). ...
... On the other hand, in the Atlantic Forest, which is considered as a biodiversity hotspot (Myers et al., 2000), the few endemic Cynolebiini occur in isolated areas separated by distributional gaps of up 430 km (Costa, 2007). More importantly, even when occurring in those areas with predominant dense rainforests, Cynolebiini species are always found in sunny places, such as patches of seasonally dry forests and coastal restinga vegetation (e.g., Costa and Amorim, 2014), never within dark dense rain forests like those reported for some of their close relatives, the Cynopoeciliini (Costa, 2016a). These data indicate that the Cynolebiini have a long history of adaptation to life in seasonal pools situated in environments of open vegetation, exposed to sunlight. ...
... (A) Atlantic Forest: corresponds to the Brazilian Atlantic Forest Province (Morrone, 2006), which is the most biologically diverse area in South America and the fourth most important biodiversity hotspot in the world (Myers et al., 2000). Several aplocheiloid genera are endemic to this area (Costa, 2009b(Costa, , 2016a, including the cynolebiine genera Nematolebias, Ophthalmolebias, and Xenurolebias (Costa, 2010). (B) Caatinga: includes the semiarid Caatinga Province (Morrone, 2006), consisting of the largest nuclei of Seasonally Dry Tropical Forests in South America (e.g., Pennington et al., 2000), as well as the short adjacent transition dry savanna in central Brazil, which shares several biotic elements with the neighbouring Caatinga (e.g., Nascimento et al., 2013). ...
The rich biological diversity of South America has motivated a series of studies associating evolution of endemic taxa with the dramatic geologic and climatic changes that occurred during the Cainozoic. The organism here studied is the killifish tribe Cynolebiini, a group of seasonal fishes uniquely inhabiting temporary pools formed during the rainy seasons. The Cynolebiini are found in open vegetation areas inserted in the main tropical and subtropical South American phytogeographical regions east of the Andes. Here, we present the first molecular phylogeny sampling all the eight genera of the Cynolebiini, using fragments of two mitochondrial and four nuclear genes for 35 species of Cynolebiini plus 19 species as outgroups. The dataset, 4448 bp, was analysed under Bayesian and maximum likelihood approaches, providing a relatively well solved tree, which retrieves high support values for the Cynolebiini and most included clades. The resulting tree was used to estimate the time of divergence in included lineages using two cyprinodontiform fossils to calibrate the tree. We further investigated historical biogeography through the likelihood-based DEC model. Our estimates indicate that divergence between the clades comprising New World and Old World aplocheiloids occurred during the Eocene, about 50 Mya, much more recent than the Gondwanan fragmentation scenario assumed in previous studies. This estimation is nearly synchronous to estimated splits involving other South American and African vertebrate clades, which have been explained by transoceanic dispersal through an ancient Atlantic island chain during the Palaeogene. We estimate that Cynolebiini split from its sister group Cynopoecilini in the Oligocene, about 25 Mya and that Cynolebiini started to diversify giving origin to the present genera during the Miocene, about 20 to 14 Mya. The Cynolebiini had an ancestral origin in the Atlantic Forest and probably were not present in the open vegetation formations of central and northeastern South America until the Middle Miocene, when expansion of dry open vegetation was favoured by cool temperatures and strike seasonality. Initial splitting between the genera Cynolebias and Simpsonichthys during the Miocene (about 14 Mya) is attributed to the uplift of the Central Brazilian Plateau.
Killifishes (Cyprinodontiformes) are a group of fish that include a high proportion of small-bodied species living in seasonal aquatic habitats, with narrow geographical distributions and high human impact. They are among the most vulnerable vertebrates in the Neotropical region, with nearly half of the species in threat categories. Herein, we propose a new phylogenetic hypothesis of the Rivulidae genus Austrolebias, based on 10 genes (six nuclear and four mitochondrial) and 191 morphological characters, including 90% of the total valid species of this genus. An updated definition and diagnosis of the existing subgenera of Austrolebias is provided, and these are erected to genera. Also, four new genera are erected to accommodate the taxonomy of the group to the current phylogenetic hypothesis. Additionally, we describe Argolebias guarani sp. nov., from a seasonal pond in the Middle Paraná River basin, which is diagnosed by a unique colour pattern. This addition reinforces this area as a biodiversity hotspot of endemicity and highlights the importance of this region for conservation. Data on the ontogenetic changes in colour pattern, chorion ornamentation of the egg and ecology of this species are also provided.
The IUCN Red List (RL) provides high-quality conservation assessments for individual species, yet the rate and scale of environmental deterioration globally challenges the conservation community to develop expedited methods for risk assessment. Here we compare threat assessments for 3,001 species of Neotropical freshwater fishes (NFF) in the IUCN–RL using readily accessible data types as proxies for extinction risk: geographic range, elevation, and species publication date. Furthermore, using geographic and taxonomic data alone, we generated preliminary conservation assessments for 2,334 NFF species currently awaiting IUCN assessment, identifying an additional 671 NFF species as potentially threatened. This number of potentially threatened species represents an increase of 59% over the number of species currently assigned to threat categories by the IUCN–RL. These results substantially expand the number of threatened NFF species from 422 currently on the IUCN RL to 1,093 species as threatened or potentially threatened, representing about 18% of all NFF species. Extinction risk is greater in species with smaller geographic ranges, which inhabit upland rivers, and which were described more recently. We propose the Central and Southern Andes, and Eastern Guiana Shield as priorities in the upcoming IUCN RL assessment of NFF species conservation risk.
