Sergio M. Q. Lima

Long-term retention of self-fertilization in a fish clade

Among vertebrate animals, only the mangrove rivulus (Kryptolebias marmoratus) was known to self-fertilize. Here, we use microsatellite analyses to document a high selfing rate (97%) in a related nominal species, Kryptolebias ocellatus, which likewise is androdioecious (populations consist of males and hermaphrodites). In contrast, we find no evidence of self-fertilization in Kryptolebias caudomarginatus (an androdioecious species closely related to the marmoratus-ocellatus clade) or in Kryptolebias brasiliensis (a dioecious outgroup). These findings indicate that the initiation of self-fertilization predated the origin of the marmoratus-ocellatus clade. From mitochondrial DNA sequences and microsatellite data, we document a substantial genetic distance between Kryptolebias marmoratus and K. ocellatus, implying that the selfing capacity has persisted in these fishes for at least several hundred thousand years.

Fish fauna of Pratagi River coastal microbasin, extreme north Atlantic Forest, Rio Grande do Norte state, northeastern Brazil

The purpose of this study was to inventory the ichthyofauna of the coastal Pratagi River basin, located on the east coast of the state, region with intense tourist activities. A total of 2,181 specimens were collected, from August 2011 to August 2013, using sieves, trawls, cast nets, traps and gillnets. Additionally, two species ( Centropomus sp. and Lutjanus alexandrei ) have only been recorded through underwater observations, summing 22 species and genera, 18 families and nine orders. Along the Pratagi drainage some human impacts were identified, mainly related to tourist activities, such as removal of riparian vegetation and sedimentation caused by the passage of vehicles on dunes. Species richness was lower near the most visited places and greater in the lower portion of the basin, due to the presence of estuarine and marine species. Apparently, a set of small waterfalls act as a barrier to some fish species, both upstream and downstream.

Inter- and intra-basin phenotypic variation in two riverine cichlids from northeastern Brazil: potential eco-evolutionary damages of São Francisco interbasin water transfer

Intraspecific morphological variation can be generated by a set of historical and ecological processes, and can be induced by anthropogenic actions. One such activity that has large-scale environmental impacts in freshwater environments is interbasin water transfer. Brazil’s Mid-Northeastern Caatinga freshwater ecoregion is going through an interbasin diversion that will link waters from São Francisco ecoregion with the four major basins of Mid-Northeastern Caatinga. Here, we aimed to evaluate the morphological variation of two cichlids, Cichlasoma orientale and Crenicichla menezesi, from both ecoregions and test, whether this morphological variation is related to historical isolation among basins and/or to local water flow regimes, through mtDNA (cytb) and geometric morphometric approaches. Our results showed, for both species, significant morphological differences among basins. However, the comparisons between genetic and morphological differences among basins were not significant. Additionally, a significant shared morphological pattern between species (body depth and mouth position) among different habitats was found. These results reinforce a potential role of environmental pressures upon fish morphology, possibly through phenotypic plasticity. The evolutionary role of morphological responses in freshwater fish populations—especially in variable environments—is discussed, as well as the potential eco-evolutionary damages that might result from the artificial river connection.

Ichthyofauna of the humid forest enclaves in the tablelands of Ibiapaba and Araripe, Northeastern Brazil

Humid highland forest enclaves are remnants of Atlantic Forest found in tablelands within the Caatinga biome (Northeastern Brazil), which emerged during interglacial periods in the Pleistocene. These ecosystems have a highly diverse and endemic fish fauna. Most earlier surveys have focused on the tableland of Borborema (Pernambuco and Paraiba States). In this study we surveyed the fish fauna of the humid forest enclaves in the tablelands of Ibiapaba and Araripe, based on samples collected in the rainy season (March and April) between 2009 and 2014. The 45 sampling points covered rivers, streams and reservoirs in five river basins belonging to three ecoregions. The species were listed according to drainage divide, and endemism was determined for each ecoregion and for the Caatinga. Our area was more species-rich (n=59) than Borborema (n=27). The samples included five introduced species and 29 species endemic to the Caatinga (49.1% of the sampled species). The distribution of Parotocinclus haroldoi was expanded to the Mid-Northeastern Caatinga ecoregion (Timonha river basin, Ceara State). Our study intends to make a significant contribution to current knowledge of the ichthyofauna in humid highland forest enclaves of semiarid Northeastern Brazil, identified as a priority in the conservation of the biodiversity in the Caatinga.

Ichthyofauna of the Gurgueia River, Parnaíba River basin, northeastern Brazil

The Gurgueia River in southern Piaui state, Brazil, is the largest affluent on the right margin of the Parnaiba River basin. This study aimed to inventory the Gurgueia River ichthyofauna, and contribute to the knowledge of fish diversity in Northeastern Brazil. We sampled 71 locations throughout the Gurgueia sub-basin between 2006 and 2014, which resulted in 90 fish species representing 67 genera, 26 families and six orders, including two non-native species. Six species are newly recorded for the Parnaiba basin ( Hasemania nana, Hemigrammus brevis, H. guyanensis, H. ora, Corydoras sp. and Cetopsorhamdia sp.), increasing its freshwater ichthyofauna to 152 species. The Gurgueia River contains 59.2% of the ichthyofauna known for the Parnaiba basin, and can be used as a reference point for the establishment of priority areas for the conservation of the freshwater fish fauna of the Brazilian Northeast.

Parotocinclus seridoensis, a new hypoptopomatine catfish (Siluriformes: Loricariidae) from the upper rio Piranhas-Açu basin, northeastern Brazil

A new species of Parotocinclus is described from the upper rio Piranhas-Acu basin, northeastern Brazil. The new species differs from all its congeners, except P. bidentatus, P. muriaensis (both from rio Paraiba do Sul basin, southeastern Brazil), and P. spilurus (rio Jaguaribe basin, northeastern Brazil) by presenting the adipose fin rudimentary or absent. The new species differs from P. bidentatus, P. muriaensis, and P. spilurus mainly by presenting the abdomen region extensively naked, with few reduced rounded dermal platelets between the pectoral girdle and the anus. Parotocinclus seridoensis is probably an endemic species of the semi-arid Caatinga, region where the genus presents high species richness.

What governs the functional diversity patterns of fishes in the headwater streams of the humid forest enclaves: environmental conditions, taxonomic diversity or biotic interactions?

The relationship between functional and taxonomic diversity is a major issue in ecology. Biodiversity in aquatic environments is strongly influenced by environmental gradients that act as dispersion and niche barriers. Environmental conditions act as filters to select functional traits, but biotic interactions also play a role in assemblage structure. In headwater streams, the relationship between functional and taxonomic diversity remains unclear. In this study we investigated how environmental conditions, taxonomic diversity and biotic interactions influence the spatial distribution of traits and functional diversity in stream fish species. Standardized sampling of fish species was carried out in 50 m sections of 16 streams located in rainforest enclaves in a semiarid region of Brazil (Caatinga biome). The functional diversity indices displayed different responses to the predictor variables used. Functional richness was mainly influenced by environmental conditions, while functional evenness was mostly determined by taxonomic diversity. On the other hand, functional dispersion was explained by a combination of environmental conditions and taxonomic diversity. The spatial distribution of fish species with the same functional traits was random, indicating that biotic interactions are not a strong predictor in these ecosystems. Channel width, pH and substrate were the most important variables in the spatial distribution of the functional traits of the fish species. Our results suggest that the functional structure of fish assemblages in headwater streams depends mainly on environmental conditions and taxonomic diversity.

Effects of Pleistocene climatic and geomorphological changes on the population structure of the restricted-range catfish Trichogenes longipinnis (Siluriformes: Trichomycteridae)

Trichogenes longipinnis Britski & Ortega is a narrowly distributed endemic and phenotypically variable catfish from the coastal basins of the Serra do Mar range in southeast Brazil. We examined patterns of mtDNA variation of this species in coastal basins of the Serra do Mar to determine the influences of past climatic and geomorphological processes in connection with the currently isolated basins. Allozyme data were also used to test the hypothesis that the different spotting patterns in the different areas could be the result of cryptic speciation. Regardless of body pigmentation, T. longipinnis specimens from across the basins were found to belong to a single species, but the populations were structured in accordance with the current hydrological watersheds, in four management units across the three distinct basins of its geographic distribution. Thus, the current genetic distribution may be best explained by both marine regressions and orogeny. Based on the low levels of genetic variation and high population structure observed, we suggest that T. longipinnis should be classified as “vulnerable” in the Brazilian red list of threatened fauna. Furthermore, we propose that the headwaters of the Parati-Mirim River basin should be incorporated as an extension of the Bocaina National Park to protect its genetically differentiated lineages.

First record of Kryptolebias hermaphroditus Costa, 2011 (Cyprinodontiformes: Rivulidae) in the extreme north Atlantic Forest mangroves, Rio Grande do Norte state, Brazil

This study records the first occurrence of Kryptolebias hermaphroditus Costa, 2011 in canals or perennial salty water pools in two mangroves of the Rio Grande do Norte state, in the estuaries of Ceara-Mirim River and Curimatau River. Due to its hermaphroditism and self-fertilization, a unique feature among vertebrates, this species is very important for many biological areas. Kryptolebias hermaphroditus depends on favorable conditions for their development, therefore, human impacts such as shrimp farming and removal of native vegetation from mangroves may affect populations of this species in northeastern Brazil.

Diversity, Distribution, and Conservation of the Caatinga Fishes: Advances and Challenges

The Caatinga, located in the semiarid region of northeastern Brazil, is dominated by a seasonally dry tropical forest and encompasses a relatively modest hydrographic network, characterized by intermittent water courses. Even the major rivers which are perennial, such as the Sao Francisco and Parnaiba, have mostly intermittent tributaries within the Caatinga. Despite some early explorations dating back to sixteenth century and the systematic compilation of fish species which started in the beginning of the nineteenth century, until recently the fish fauna of the Caatinga biome has been considered poorly known due to the lack of adequate sampling. The present study assessed the current state of knowledge on this fish fauna, in terms of species richness, endemism, and conservation status, based on a literature review, recent field work, and collection records. Our major result was finding a considerable increment in the species richness in the biome when compared with previous estimates, totaling 386 fish species, 371 of which are native freshwater species, 203 are considered endemic to the hydrographic ecoregions where the Caatinga occurs, 15 are introduced from other basins, and 15 listed species have doubtful taxonomic status. Additionally, 32 species are currently recognized as undescribed. We also highlight that the 33 endangered fish species in the Caatinga are possibly not included in protected areas, and that the conservation units in the biome are not enough to ensure protection for endemic and endangered fish species.