A major part of the described species is understudied, falling into the Linnean shortfall. This is a major concern for cryptic species, which require integrative approaches to better evaluate their ...diversity. We conducted morphological analyses using specimens of Stellifer punctatissimus, S. gomezi, and S. menezesi to reassess their taxonomical identity. We evaluated the allometric and sexual components of the morphology of the Stellifer punctatissimus species complex, and tested and discussed species hypotheses. The combined evidence of our work and previous studies agrees with the current morphological hypothesis of three species, as opposed to the two-lineage molecular hypothesis. However, as cryptic species, they overlap in most their traits, especially females and juveniles. Previously unaccounted variation of allometric and sexually dimorphic characters in this species complex revealed a confounding effect that might explain past and current taxonomic errors. Taxonomical practice of using body depth as a diagnostic character had led to juveniles and females being, respectively, described as a different species or wrongfully identified. Hence, taxonomical studies demand better assessment of allometric and sexual dimorphism components. Herein, we present new characters in a key to the Atlantic species of Stellifer, which disclose size and sexual variation unnoticed in previous studies. The contrasting growth patterns among these species could imply distinct habitat use. As a result, it could be suggested that such species are under different threats, which highlights the need of differential management and conservation strategies.
•Incomplete sampling threatens understanding of morphological diversity in cryptic species.•Past taxonomic mistakes led to misidentification especially of females and juveniles.•Confounding effects between allometry and sexual dimorphism influence taxonomic errors.•Our results suggest latitudinal sexual dimorphism in tropical marine fishes.
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.
Characidium tapuia, a new species apparently endemic to the rio Parnaíba basin, Brazil, is described. The new species is easily distinguished from congeners, except C. lanei, C. nana, and C. samurai, ...by having a broad and conspicuous dark lateral stripe, extending from the tip of snout to the end of caudal peduncle and by the absence of dark vertical bars on body of specimens larger than 23.0 mm SL. Characidium tapuia differs from the aforementioned species by a series of features, including 12 circumpeduncular scales (vs. 13 or 14 in C. lanei and C. samurai), presence of parietal branch of the supraorbital canal (vs. absence in C. lanei and C. nana), complete lateral line and adipose fin present (vs. lateral line incomplete and adipose fin absent in C. nana), and midlateral stripe with irregular borders (vs. lateral stripe with overall straight borders in C. samurai).
Hypsolebia antenori is a seasonal killifish considered to be broadly distributed along the Caatingas basins of northeastern Brazil, with records in the coastal drainages of the rio Pacoti, rio ...Jaguaribe, crrego Virglio and rio Apodi-Mossor basins. Based on morphological characters and molecular phylogenetic reconstructions, it was possible to diagnose two new species and restrict H. antenori to the rio Jaguaribe basin. Hypsolebias gongobira new species is described from a temporary pool in the rio Pacoti basin in Cear State, in syntopy with the species threatened H. longignatus. Hypsolebias bonita new species occurs in the floodplains of the rio Apodi-Mossor basin and in the crrego Virglio microbasin in the Furna Feia National Park, in Rio Grande do Norte State. We also discuss the conservation status of these new species and how the So Francisco Interbasin Water transfer, and the agricultural and urban expansion in the semiarid may be adversely affecting these seasonal killifishes.
Abstract Three new species of Eigenmannia belonging to the E. trilineata species-group are described. The first species is described from rio Mearim basin and can be diagnosed by lateral line stripe ...restricted to last two thirds of body, superior midlateral stripe present, 176–205 anal-fin rays, 10–15 scales rows above lateral line, 109–125 lateral line scales, 19–23 premaxillary teeth, 20–29 dentary teeth, 6–10 endopterygoid teeth, and 13–14 precaudal vertebrae. The second species is described from upper rio Parnaíba, and can be diagnosed by lateral line stripe restricted to last two-thirds of body, ii,11–13 pectoral-fin rays, 180–196 anal-fin rays, 12–15 scales rows above lateral line, 10–14 premaxillary teeth, 15–21 dentary teeth, 8–10 endopterygoid teeth, and 14 precaudal vertebrae. The third species is widespread in rio Parnaíba basin, and can be diagnosed by absence of lateral line stripe, absence of superior midlateral stripe, 182–228 anal-fin rays, 12–15 scales rows above lateral line, 107–131 lateral line scales, 32–34 premaxillary teeth, 35–44 dentary teeth, 9–12 endopterygoid teeth, and 13 precaudal vertebrae. A dichotomous key and the conservation status for the three species are provided.
Resumo Três espécies novas de Eigenmannia pertencentes ao grupo E. trilineata são descritas. A primeira espécie é descrita para a bacia do rio Mearim e pode ser diagnosticada por apresentar faixa da linha lateral restrita aos últimos dois terços do corpo, faixa médio lateral superior presente, 176–205 raios na nadadeira anal, 10–15 fileiras de escamas acima da linha lateral, 109–125 escamas na linha lateral, 19–23 dentes pré-maxilares, 20–29 dentes no dentário, 6–10 dentes no endopterigóide, e 13–14 vértebras pré-caudais. A segunda espécie é descrita do alto rio Parnaíba, e pode ser diagnosticada por apresentar faixa da linha lateral restrita aos últimos dois terços do corpo, ii,11–13 raios na nadadeira peitoral, 180–196 raios na nadadeira anal, 12–15 fileiras de escamas acima da linha lateral, 10–14 dentes pré-maxilares, 15–21 dentes no dentário, 8–10 dentes no endopterigóide, e 14 vértebras pré-caudais. A terceira espécie está amplamente distribuída na bacia do rio Parnaíba, e pode ser diagnosticada pela ausência de faixa na linha lateral, ausência da faixa médio lateral superior, 182–228 raios na nadadeira anal, 12–15 fileiras de escamas acima da linha lateral, 107–131 escamas na linha lateral, 32–34 dentes pré-maxilares, 35–44 dentes no dentário, 9–12 dentes no endopterigóides, e 13 vértebras pré-caudais. Uma chave dicotômica e o status de conservação para as três espécies são fornecidas.
A new species of Parotocinclus is described from the Rio Mamanguape basin, in the State of Paraíba, north‐eastern Brazil. The new species can be distinguished from all of its congeners, except for P. ...bahiensis, P. cesarpintoi, P. jumbo, P. nandae and P. spilosoma, by the presence of an abdomen covered by a few small and dispersed platelets (vs. an abdomen entirely covered by large plates in adult individuals or the absence of plates in that region). The new species differs from those mentioned above with respect to several features, such as an exposed pectoral girdle and supporting odontodes medially and laterally, the number of premaxillary and dentary teeth, odontodes covering only the lateral portion of the cleithrum and the absence of irregular golden lines on the head and body (colour in vivo). The new species was collected only in the upper and middle portions of the Rio Mamanguape basin, suggesting a geographic distribution restricted to the Caatinga biome.
The mid‐north‐eastern Caatinga is a semiarid freshwater ecoregion in North‐eastern Brazil that is dominated by temporary rivers and is currently classified as one of the least ichthyologically‐known ...ecoregions in the world. The present study aimed to provide an updated checklist of mid‐north‐eastern Caatinga ecoregion (MNCE) freshwater fish species and evaluate their taxonomic identity using morphology, DNA barcoding and multiple species delimitation approaches. After reviewing published studies and ichthyological collections, 119 species were identified. Among these were 94 putatively valid native and 14 non‐native species, five undescribed native species, four new records for the MNCE, 11 potential cases of misidentification and 14 species listed as inquirenda. Additionally, 252 individuals from 49 species were barcoded, revealing three potential taxonomic synonyms. The combined molecular approaches estimated a total of 91 native species, although a finalized species list for the MNCE awaits additional taxonomic revisions and field surveys. This study provides the most up‐to‐date species checklist for the MNCE and a molecular reference database for identifying MNCE fishes with DNA barcodes. Results highlight the need to integrate traditional taxonomy with molecular approaches to correctly identify species, especially in taxonomically problematic ecoregions such as the MNCE.
Abstract Sciaenidae species (croakers and drums) are known for specializations in their sensory apparatus, such as otoliths and lateral line. Within this family, some Stelliferinae members remain ...taxonomically unresolved due to their cryptic aspects and low phenotypic disparities. Stellifer punctatissimus comprises a species complex putatively formed by three species on morphological grounds, but molecular data have indicated only two evolutionary lineages. Herein, we tested the hypothesis that this complex is composed of Stellifer gomezi (GM), S. menezesi (MN), and S. punctatissimus (PC), using the otolith shape and morphology to differentiate them. Seventy-seven sagittal otoliths (GM = 30, MN = 30, PC = 17) were photographed to outline the otolith contour by Elliptical Fourier descriptors. Ten otoliths for each group were used to detect shape variation in the sulcus acusticus through semilandmarks. Differences in otolith shape contour were recorded among the species by PERMANOVA (Pseudo-F = 4.02, df = 2, p < 0.001) and corroborated by the Linear Discriminant Analysis, which demonstrated three partially segregated groups with satisfactory re-classification rates. A larger sulcus acusticus (GM and MN), rounded projection (PC), and distinct rectangularity pattern were also recorded. Our results support the morphological hypothesis and thus contribute to narrowing the taxonomic gaps in Sciaenidae.
Resumo As espécies de Sciaenidae (corvinas e pescadas) são conhecidas por especializações nos aparatos sensoriais, como otólitos e linha lateral. Nesta família, alguns membros de Stelliferinae permanecem com sua taxonomia não resolvida devido às características crípticas e baixas disparidades fenotípicas. Stellifer punctatissimus supostamente compreende um complexo formado por três espécies, mas os dados moleculares têm indicado apenas duas linhagens evolutivas. Aqui, testamos a hipótese de que esse complexo é composto por Stellifer gomezi (GM), S. menezesi (MN), e S. punctatissimus (PC), usando a forma e morfologia do otólito para diferenciá-las. Setenta e sete otólitos sagita (GM = 30, MN = 30, PC = 17) foram fotografados para delimitar o seu contorno pelos descritores Elípticos de Fourier. Dez otólitos, por grupo, foram usados para detectar a variação de forma no sulcus acusticus através dos semilandmarks. Foram registradas diferenças na forma do otólito entre as espécies através da PERMANOVA (Pseudo-F = 4,02, df = 2, p < 0,001) e pela análise discriminante linear, demonstrando três grupos parcialmente segregados com taxas de reclassificação satisfatórias. Também foram registrados um sulcus acusticus mais largo (GM e MN), projeção arredondada (PC) e padrões alométricos distintos no índice de retangularidade. Nossos resultados apoiam a hipótese morfológica; assim, contribuem na redução das lacunas taxonômicas em Sciaenidae.
Abstract Trichomycterid catfishes have long been considered as absent in the Parnaíba River basin, Northeastern Brazil, in what constitutes their most conspicuous gap in geographic distribution. ...Herein we report on the first occurrence of the family in that basin. The new species is described from the riacho da Volta, right tributary to the upper rio Parnaíba, Piauí State. It is distinguished from its congeners by the combination of two or three pairs of ribs; 36–38 post Weberian vertebrae; a color pattern composed of round, similar-sized, non-coalescent spots; I,5 pectoral-fin rays; the first haemal arch on the 5th or 6th vertebrae; and the first completely fused (to the tip) haemal spine on the 15th vertebra. A putative autapomorphy is the partial (minimally 50% of their length) or total fusion between the anterior arms of the basipterygium. Preliminary evidence suggests that the new species can be related to northern South American forms, a pattern that fits the general Amazonian relationships of the fishes in the Parnaíba River drainage. Although the new species fills in an important qualitative gap in trichomycterid continental distribution, the taxon is apparently rare and extremely restricted in distribution, with the type series being its only record so far. The paucity of trichomycterids in the Parnaíba remains a puzzling biogeographical phenomenon.
Resumo Os bagres tricomicterídeos têm estado surpreendentemente ausentes na bacia do rio Parnaíba, Nordeste do Brasil, no que constitui sua lacuna mais evidente na distribuição. Relatamos a primeira ocorrência da família na bacia. A espécie nova é descrita do riacho da Volta, tributário do lado direito do alto rio Parnaíba em Uruçuí, Piauí. Ela é distinguida de suas congêneres pela combinação de dois ou três pares de costelas; 36–38 vértebras pós weberianas; padrão de coloração composto de manchas arredondas, de tamanhos semelhantes e não coalescentes; I,5 raios nas nadadeiras peitorais; o primeiro arco haemal na 5° ou 6° vértebra, e o primeiro espinho haemal completamente fusionado (até a extremidade) na 15° vértebra. Uma possível autapomorfia é a fusão parcial (mínimo de 50% do seu comprimento) ou total entre os braços anteriores do basiopterígio. Evidências preliminares sugerem que a espécie nova pode estar relacionada com as formas do norte da América do Sul, padrão que se encaixa nas relações amazônicas dos peixes da drenagem do rio Parnaíba. Embora a espécie nova preencha uma importante lacuna na distribuição continental dos tricomicterídeos, o táxon é aparentemente raro e extremamente restrito em distribuição, sendo a série-tipo seu único registro até o momento.
Abstract A new species of cloud fish of the genus Hypsolebias is described from a temporary pool in the rio Trairi basin, Rio Grande do Norte State, Brazil. It is the first record of the genus ...Hypsolebias for the basin. The new speciesbelongs to the H. flammeus species-group, which is composed of the species H. alternatus, H. brunoi, H. delucai, H. fasciatus, H. longignatus, H. marginatus, H. multiradiatus, and H. flammeus. The new species differs from all other species of the group, except H. flammeus, H. multiradiatus,and H. brunoi, by male color pattern and the presence of a metallic blue sheen surrounding the black spots of females. It differs from H. flammeus, H. multiradiatus and H. brunoi by dorsal and anal fin shape (both rounded vs. pointed) and by the orientation of the reddish-brown bars on the body and anal fin of males (diagonal vs. vertical). The new species differs from its congeners of Northeast Brazil mainly by the higher number of dorsal fin rays in males and the higher number of scales in the longitudinal series.
Resumo Uma nova espécie de peixe das nuvens, gênero Hypsolebias, é descrita de uma poça temporária localizada na bacia do rio Trairi, Estado do Rio Grande do Norte, Brasil. É a primeira ocorrência do gênero Hypsolebias na bacia do rio Trairi. A nova Hypsolebias pertence ao grupo de espécies H. flammeus que é composto pelas espécies H. alternatus, H. brunoi, H. delucai, H. fasciatus, H. flammeus, H. longignatus, H. marginatus e H. multiradiatus. A nova espécie difere de todas as espécies desse grupo, exceto H. flammeus, H. multiradiatus e H. brunoi, pelo padrão de coloração do macho e pela presença de um brilho azul metálico envolvendo as manchas pretas na fêmea. Difere de H. flammeus, H. multiradiatus e H. brunoi pela forma das nadadeiras dorsal e anal (arredondada vs. pontiaguda) e pela orientação das barras castanhas avermelhadas no corpo e na nadadeira anal nos machos (diagonal vs. vertical). A nova espécie difere de outras congêneres do Nordeste do Brasil principalmente pelo elevado número de raios na nadadeira dorsal nos machos e pelo maior número de escamas na série longitudinal.
