Apparent signal of competition limiting diversification after ecological transitions from marine to freshwater habitats.

Adaptive radiations are typically triggered when a lineage encounters a significant range of open niche space (ecological opportunity), stemming from colonisation of new areas, extinction of competitors or key innovations. The most well-known of these is the colonisation of new areas, through either dispersal into new regions or the invasion of novel ecological regimes. One aspect of ecological opportunity that has rarely been studied, however, is the extent to which pre-existent competitors act to limit diversification in newly colonised adaptive zones. Herein, we show that in multiple geographically independent invasions of freshwaters by marine Sea Catfishes (Ariidae), rates of both morphological disparification and lineage diversification are inversely related to the presence and diversity of other freshwater fish lineages. Only in one region (Australia-New Guinea) with an otherwise depauperate freshwater fauna, has an ariid invasion gained any substantial traction. This is true at both regional and community scales, suggesting that competitive constraints may be an important factor regulating adaptive radiation.

Taxonomy of Centropomus Lacépède, 1802 (Perciformes: Centropomidae), with focus on the Atlantic species of the genus.

Centropomus Lacépède, 1802 comprises 13 species of the fishes popularly knows as snooks, distributed in both Atlantic and Pacific coasts of America. Despite several studies on the group, conflicting taxonomic classifications still exist, including overlapping diagnostic characters, rendering species diagnoses extremely difficult. Herein, we review the taxonomy of Centropomus to elucidate species identities, redefine their diagnoses and to assess interspecific relationships based on the examination of 376 specimens. The study included complementary approaches, as analyses of external morphologic characters, linear and geometric morphometrics, and molecular analyses. Forty-nine characters were used for external morphology, 17 discrete plus 32 linear measurements. Shape and size were analyzed through geometric morphometrics of 185 specimens in lateral view. Partial sequences of the gene cytochrome c oxidase I were obtained for 129 specimens representing 11 species. Based on the consistent results retrieved from the morphologic and molecular analyses, we recognized six species of Centropomus from the Atlantic coast (C. ensiferus, C. irae, C. parallelus, C. pectinatus, C. poeyi and C. undecimalis). Centropomus mexicanus is treated as a junior synonym of C. parallelus. Six species from the Pacific coast are also tentatively recognized (C. armatus, C. medius, C. nigrescens, C. robalito, C. unionensis, and C. viridis), however further studies on the Pacific species are still needed. Information on type material, diagnosis, distribution, and taxonomic comments are provided for each species. An identification key to the species of Centropomus is presented.

Cathorops festae (Boulenger 1898) (Siluriformes; Ariidae), a valid species from Ecuador and Peru.

Over the past decade, the Sea Catfish (Ariidae) genus Cathorops has been the focus of a major taxonomic review, which has resulted in the revalidation of five synonymized nominal species, and the recognition of seven new species. With 21 valid species, Cathorops is currently the most species-rich genus of Ariidae in the New World. The principal lacuna in the taxonomic knowledge of genus species is the uncertain status of Arius festae Boulenger, 1898, described from Naranjal, in the Guayas River basin of Ecuador. In the present study Cathorops festae is redescribed as a valid species based on morphological and molecular data.

Review of the harvestfishes, genus Peprilus (Perciformes: Stromateidae), of the Atlantic coast of South America.

Currently, seven valid species are recognized in the genus Peprilus. Found from United States to Argentina, Peprilus paru has a complex nomenclatural history, with seven junior synonyms, three from North America and four from South America. As there has been no recent research, it remains unclear whether species representatives in the north-south axis represent different populations of a single species or distinct species. By comparison of type specimens as well as a comprehensive collection of non-type specimens, this paper aims to clarify the taxonomic status of the nominal species listed as junior synonyms of Peprilus paru in the Atlantic side of South America. Based on morphological data and DNA barcoding, Peprilus crenulatus Cuvier, 1829 and P. xanthurus (Quoy & Gaimard, 1825) are resurrected, while Rhombus argentipinnis Cuvier, 1833 and Rhombus orbicularis Guichenot, 1866, are considered to be junior synonyms of P. crenulatus.

The Tonkin weakfish, Cynoscion similis (Sciaenidae, Perciformes), an endemic species of the Amazonas-Orinoco Plume

Despite its importance in biogeographical, ecological, and commercial terms, the fish fauna of the northern Brazilian coast is still poorly known, representing the least sampled portion of the Brazilian Exclusive Economic Zone. We collected Tonkin weakfish, Cynoscion similis specimens during extensive surveys of the northern Brazilian coast and concluded that C. similis is common in this region. While the species had not previously been reported for the northern Brazilian state of Pará, it may have been recorded in studies of industrial fisheries, being identified only as Cynoscion sp. or by the common name pescada negra. This reinforces the need for the reliable taxonomical identification of species, to guarantee the collection of accurate data on ecology and fisheries, and ultimately, support the development of effective conservation strategies. Here we provide additional morphological and molecular data to distinguish Cynoscion similis from the closely related Cynoscion jamaicensis, and other congeners. (AU)

Early Pleistocene lineages of Bagre bagre (Linnaeus, 1766) (Siluriformes: Ariidae), from the Atlantic coast of South America, with insights into the demography and biogeography of the species

Coastal and marine environments are characterized by a lack of evident physical barriers or geographic isolation, and it may be difficult to understand how divergence can arise and be sustained in marine environments. The identification of 'soft' barriers is a crucial step towards the understanding of gene flow in marine environments. The marine catfishes of the family Ariidae are a demersal group with restricted migratory behavior, no pelagic larval stages, and mechanisms of larval retention, representing a potentially useful model for the understanding of historical processes of allopatric speciation in the marine environment. In the present study, two lineages of the Coco sea catfish, Bagre bagre , were recognized from their complete segregation at both mitochondrial and morphological levels. One lineage is distributed between Venezuela and the northern coast of Brazil, including the semiarid northeast coast, while the second lineage is found on the eastern coast of Brazil, including the humid northeast coast. Based on distribution area, habitats preference, and genetic variability, inferences are made in relation to biogeography and demography of lineages in Atlantic coast of South America.

Ambientes marinhos costeiros são caracterizados pela falta de barreiras físicas evidentes e ausência de isolamento geográfico, sendo difícil compreender como diferentes linhagens podem surgir e ser mantidas nestes ambientes. A identificação de barreiras permeáveis é um passo importante para a compreensão do fluxo gênico em ambientes marinhos. Os bagres marinhos da família Ariidae são um grupo demersal, com mecanismos de retenção larval e sem comportamento migratório ou estágio larval pelágico, representando um grupo potencialmente útil para a compreensão de processos históricos de especiação alopátrica no ambiente marinho. No presente estudo, duas linhagens do bandeirado ou bagre de fita, Bagre bagre , são reconhecidas com base na completa segregação mitocondrial e morfológica. Uma linhagem é encontrada da Venezuela à costa norte do Brasil, incluindo a costa nordeste semi-árida, enquanto a segunda linhagem é encontrada na costa leste e sudeste do Brasil, incluindo a costa nordeste úmida. Com base na área de distribuição, habitat preferencial e a variabilidade genética, inferências são feitas em relação à biogeografia e demografia das duas linhagens na costa do Atlântico da América do Sul.

Color pattern variation in Trichomycterus iheringi (Eigenmann, 1917) (Siluriformes: Trichomycteridae) from rio Itatinga and rio Claro, São Paulo, Brazil

Color pattern is recognized as an important characteristic for diagnosing Trichomycterus species and for elucidating their relationships. An analysis based on morphological and molecular data confirms the existence of a single species of Trichomycterus in the rio Itatinga, a costal river drainage on the escarpment of the Serra do Mar and the rio Claro on the upper course of the rio Tietê. The only species found, Trichomycterus iheringi, shows two clearly distinct patterns of body pigmentation and intermediate color patterns related to body size and microhabitat preference.

O padrão de coloração é reconhecido como uma característica importante para a diagnose das espécies do gênero Trichomycterus e no reconhecimento de suas relações de parentesco. A análise baseada em dados morfológicos e moleculares confirma a existência de uma única espécie de Trichomycterus no rio Itatinga, drenagem litorânea da Serra do Mar e no rio Claro, curso superior do rio Tietê. A única espécie do gênero encontrada, Trichomycterus iheringi, apresenta dois padrões de pigmentação do corpo bastante distintos e padrões de coloração intermediários relacionados ao tamanho corporal e ao micro-habitat.

Revision of the species of the genus Cathorops (Siluriformes: Ariidae) from Mesoamerica and the Central American Caribbean, with description of three new species

The ariid genus Cathorops includes species that occur mainly in estuarine and freshwater habitats of the eastern and western coasts of southern Mexico, Central and South America. The species of Cathorops from the Mesoamerica (Atlantic slope) and Caribbean Central America are revised, and three new species are described: C. belizensis from mangrove areas in Belize; C. higuchii from shallow coastal areas and coastal rivers in the Central American Caribbean, from Honduras to Panama; and C. kailolae from río Usumacinta and lago Izabal basins in Mexico and Guatemala. Additionally, C. aguadulce, from the río Papaloapan basin in Mexico, and C. melanopus from the río Motagua basin in Guatemala and Honduras, are redescribed and their geographic distributions are revised.

O gênero de ariídeos Cathorops inclui espécies que habitam principalmente águas doces e estuarinas das plataformas orientais e ocidentais do sul do México, Américas do Sul e Central. Neste estudo, se apresenta uma revisão das espécies de Cathorops da Mesoamérica (bacias do Atlântico) e Caribe centroamericano, incluindo a descrição de três espécies novas: C. belizensis, de áreas de manglar em Belice; C. higuchii, de águas costeiras rasas e rios costeiros do Caribe centroamericano, desde Honduras até o Panamá; e C. kailolae, das bacias do rio Usumacinta e lago Izabal no México e Guatemala. Adicionalmente, se redescrevem C. aguadulce, da bacia do rio Papaloapan no México, e C. melanopus, da bacia do rio Motagua na Guatemala e Honduras, apresentando-se uma revisão de suas distribuições geográficas.