Anatomy, ecology, and behavior of a new species of Scleronema Eigenmann, 1917 (Siluriformes: Trichomycteridae) from coastal drainages in the southern Brazilian Atlantic Rainforest, with comments on the monophyly and phylogeny of the genus.

A new species of Scleronema (Trichomycteridae) is described from the lowlands of three coastal river basins in the Atlantic Forest of the Santa Catarina state, Southern Brazil. Aspects of the anatomy, reproduction, diet, feeding behavior and habitat of the new species are described and discussed in comparison with related taxa. The conservation status of the new species, which currently faces several threats due to environmental impacts on its region of occurrence, is established. Based on characteristics observed in the new species, as well as in most of its congeners, the phylogenetic position and monophyly of Scleronema are discussed and traits considered synapomorphic for the subgenera Plesioscleronema and Scleronema are reviewed. The monophyly of the genus Scleronema is supported by a new synapomorphy. In addition, two new synapomorphies, one of which based on behavior, are suggested for the subgenus Scleronema, justifying the inclusion of the new species. Within the subgenus Scleronema, the new species is assigned to the S. minutum group, which currently includes the majority of species of the genus, due to the presence of synapomorphic traits related to the body shape, maxillary barbel, skin flap of the opercle, caudal and pectoral fins, as well as osteological features of the lower jaw, hyoid arch, and postcranial axial skeleton. The species herein described differs from all its congeners by a combination of characters from various morphological complexes, which are described in detail using different methodologies, including radiography, whole-specimen clearing and double-staining procedures, and tridimensional computer nanotomography (3D nano-CT).

Rediscovery of Rhyacoglanis pulcher (Boulenger, 1887) (Siluriformes: Pseudopimelodidae), a rare rheophilic bumblebee catfish from Ecuadorian Amazon.

Rhyacoglanis pulcher is a rare Neotropical rheophilic bumblebee catfish known only from the type locality in the Cis-Andean Amazon region, Ecuador, and the type-species of the genus. So far, the three syntypes collected in 1880 were the only specimens unambiguously associated to the name R. pulcher available in scientific collections. Recently, a specimen was discovered in a fast-flowing stretch of the Villano river, a tributary of the Curaray river, Napo river basin, Ecuador, representing a new record after nearly 140 years. Here, we present this new record, identified by morphology, provide the DNA barcode sequence of the specimen, and propose why the species of Rhyacoglanis are scarce in zoological collections. Additionally, we discuss the intraspecific variation in the color pattern observed in R. pulcher.

The record and threats of the invasion of palometa Serrasalmus maculatus (Characiformes: Serrasalmidae) in the Patos lagoon drainage, southern Brazil.

We report the occurrence of an invasive alien species, palometa Serrasalmus maculatus, in the Patos Lagoon drainage. Primary occurrence data were based on three specimens captured and preserved as vouchers in scientific collections. Additionally, we searched for secondary records from unpublished scientific sources, public agencies reports and media news to find additional reports. We discussed the possible pathways of invasion, suggesting as the vector of introduction transpositions from the Uruguay River basin. Ecological implications for ichthyofauna, environmental impacts and risk of other events of invasion in the adjoining basins are discussed.

A new species of Cambeva (Siluriformes, Trichomycteridae) from the Rio Iguaçu basin, Paraná State, Brazil and redescription of Cambeva stawiarski (Miranda Ribeiro 1968).

This work aimed to describe Cambeva cauim, sp. nov., endemic to the Rio Iguaçu basin, Brazil and redescribe Cambeva stawiarski using external and internal morphological data through the revision of specimens deposited in fish collections, including the type material. In this process, we have also added comments on the possible type locality of C. stawiarski. C. cauim, sp. nov. and C. stawiarski are mainly diagnosed by the anatomy and number of procurrent caudal-fin rays in addition to colouration and several meristic and morphometric characters. Both species are compared with other possibly related species and their synapomorphic characters are discussed. C. cauim, sp. nov. and C. stawiarski along with eight other congeners are endemic to the Rio Iguaçu basin, a high impacted freshwater region which could be considered as a biodiversity hotspot to the genus.

Taxonomical study of Trichomycterus (Siluriformes: Trichomycteridae) from the Ribeira de Iguape River basin reveals a new species recorded in the early 20th century.

A new species of Trichomycterus endemic to the Ribeira de Iguape River basin, southeastern Brazil, was studied based on morphological and molecular evidence. This species had an outer layer of coloration composed of scattered, round, black or dark-brown spots smaller or equivalent in size to the circumference of the eye; eight pectoral-fin rays; 28-29 opercular odontodes; 54-56 interopercular odontodes; and supraorbital line of the laterosensory system not interrupted, with pores s2 absent. Two other species of Trichomycterus from the Ribeira de Iguape River basin are recorded, and their taxonomic status is discussed: Trichomycterus alternatus and Trichomycterus jacupiranga were not differentiated using molecular analysis but may be consistently distinguished based on morphology. The phylogenetic relationships of the co-occurring species, T. alternatus and Cambeva zonata, were inferred using mitochondrial data, reinforcing the taxonomic status of these recently revised species that have a complex taxonomy. In addition, a new combination for Trichomycterus taroba with its inclusion in the genus Cambeva is recommended.

Systematic revision of the Neotropical catfish genus Scleronema (Siluriformes: Trichomycteridae), with descriptions of six new species from Pampa grasslands

The Neotropical genus Scleronema is revised based on the re-examination of the type specimens and 1,713 newly collected specimens. Scleronema is diagnosed from other trichomycterids by the following unambiguous derived characters: fleshy flap at the base of the maxillary barbell; skin flap in the posterior margin of the opercle; articulation between the autopalatine and the vomer ventrally located, with the medial margins of the autopalatines very close to each other; and autopalatine with an interrupted or not interrupted ossified arch-shaped process on its dorsal surface forming a canal. Scleronema minutum and S. operculatum are redescribed, S. angustirostre is considered a junior synonym of S. minutum, and six new species are described. A lectotype is designated for Trichomycterus minutus. The type localities of S. angustirostre, S. minutum, and S. operculatum are reviewed in order to correct erroneous information cited in articles and catalogs subsequent to the original descriptions. Species of Scleronema are geographically distributed in the La Plata basin and Atlantic coastal drainages from Southern Brazil, Southern Paraguay, Northeastern Argentina and Uruguay. They inhabit rivers or streams with sand- or gravel-bottoms across the Pampa grasslands. We provide evidences to recognize two putative monophyletic units within the genus, namely the S. minutum species group and the S. operculatum species group, and discuss the distribution patterns of their species.(AU)

O gênero Neotropical Scleronema é revisado com base na análise do material-tipo e outros 1.713 espécimes recentemente coletados. Scleronema é diagnosticado de outros tricomicterídeos pelos seguintes caracteres derivados não ambíguos: aba de pele na base do barbilhão maxilar; aba de pele na margem posterior do opérculo; articulação entre o autopalatino e o vômer posicionada ventralmente, deixando as margens mediais dos autopalatinos muito próximas entre si; e o autopalatino com um processo com formato de arco na sua superfície dorsal. Scleronema minutum e S. operculatum são redescritas, S. angustirostre é considerada um sinônimo júnior de S. minutum e seis novas espécies são descritas. Um lectótipo é designado para S. minutum. As localidades-tipo de S. angustirostre, S. minutum e S. operculatum são revisadas com o intuito de corrigir informações errôneas citadas em artigos e catálogos após suas descrições. As espécies de Scleronema distribuem-se na bacia do rio da Plata e drenagens costeiras atlânticas no sul do Brasil, sul do Paraguai, nordeste da Argentina e Uruguai, habitando rios e riachos ao longo do Pampa com fundos de areia ou cascalho. Dois grupos de espécies supostamente monofiléticos, o grupo S. minutum e o grupo S. operculatum, são reconhecidos no gênero e os padrões de distribuição de suas espécies são discutidos.(AU)

Living in the waterfalls: A new species of Trichomycterus (Siluriformes: Trichomycteridae) from Tabay stream, Misiones, Argentina.

A new species assigned to the genus Trichomycterus from the area of the waterfalls of Tabay stream, Paraná River basin, Misiones, Argentina, is described. Trichomycterus ytororo sp. nov. is distinguished from all other species in the genus by the presence of 31-35 dorsal procurrent caudal-fin rays and the combination of some external characters such as: coloration, number of pectoral-fin rays and pores of the laterosensory canals. The new taxon belongs to a presumably monophyletic group of species composed of T. crassicaudatus, T. igobi, and T. stawiarski based on the presence of 24 or more thickly ossified and rigid procurrent caudal-fin rays with a slender distal tip extending along the tips of at least ten neural spines.

Review of the Odontesthes perugiae species group from Río de La Plata drainage, with the description of a new species (Atherinomorpha: Atherinopsidae).

Specimens presently identified as belonging to Odontesthes perugiae species group from rio Paraná, rio Uruguay and rio Negro in Argentina, Brazil and Uruguay are revised. Two species are recognized: Odontesthes perugiae, type species of the genus with Odontesthes orientalis as a junior synonym, and a new species described herein. Odontesthes perugiae is redescribed and its distribution restricted to the lower rio Paraná, lower rio Uruguay and rio Negro basins. The new species is endemic from the upper rio Uruguay above Salto do Yucumã (Brazil) or Saltos del Moconá (Argentina) falls. Both species share with the remaining taxa included in the O. perugiae species-group (O. bicudo, O. ledae, O. mirinensis, and O. piquava) the possession of teeth of the outer row on dentary and premaxilla shorter than those in the inner row, being distinguished from them by the number of gill rakers, body measurements and some osteological characters.

A new species of Ituglanis (Siluriformes: Trichomycteridae) from the rio Uruguai basin, southern Brazil

A new species of Ituglanis associated to the grasslands of the Pampa biome is described from the rio Uruguai basin, southern Brazil. The new species is distinguished from its congeners by the low number of ribs and by a unique color pattern composed of an outer layer with scattered round black blotches equivalent in size to the eye circumference over a reddish brown background on the lateral surface of the body. We provide the genetic sequences of the mitochondrial gene Cytochrome c Oxydase subunit I (COI) for three of the paratypes and discuss aspects about the recent discovery of the new species.(AU)

Uma nova espécie de Ituglanis, associada aos campos do bioma Pampa, é descrita para a bacia do rio Uruguai no sul do Brasil. A nova espécie distingue-se de todos seus congêneres pelo pequeno número de costelas e por um padrão de coloração único que consiste de manchas pretas arredondadas de tamanho equivalente à circunferência do olho sobre um fundo marrom avermelhado na superfície lateral do corpo. Sequências genéticas do gene mitocondrial Citocromo Oxidase subunidade I (COI) para três dos parátipos são fornecidas, e aspectos sobre a recente descoberta da nova espécie são discutidos.(AU)

Inventory of the freshwater fishes from a densely collected area in South America-a case study of the current knowledge of Neotropical fish diversity.

We herein analyse the history of the description of the freshwater fish fauna from three drainages in one of the most densely collected areas of Brazil, and possibly of South America, the Rio Grande do Sul State, southern Brazil. An updated inventory of the freshwater fish species from rio Uruguay (partial) in Brazil, Laguna dos Patos (complete) and rio Tramandaí basins (complete) is presented. We found the number of new species described in these drainages increased nearly 56% since 1981, reaching a total of 422 species, but even now 10% of this number still corresponds to undescribed species. This rate of species description suggests that previous estimates of the Neotropical fish fauna are low, and we predict a final number of Neotropical fishes larger than the largest prediction estimate (8,000 species), after other regions of South and Central Americas become densely sampled. We discuss and attempt to demonstrate that species diversity knowledge is historically and strictly related to collecting efforts. We also demonstrate that the ecoregions in eastern South America with the highest density of species per area correspond to the areas more densely sampled in collections, and this may represent a bias in such kinds of analyses. This uneven sampling in Brazilian regions is apparently associated with the uneven distribution of Zoological research centers in different regions of the country. Small-sized species represents an important source of new species, along with little explored regions or little explored habitats, sometimes associated with restricted range species, and species complexes that need revisionary work. In contrast to other Neotropical regions, Atheriniformes are relatively diverse, sharing the fifth place in species richness with Gymnotiformes, and there is a remarkably high number of species of Rivulidae. Eight species are endemic to the rio Tramandaí drainage, 68 to the Laguna dos Patos system, and 78 to the rio Uruguay drainage. Almost 10% of the freshwater fish species are "Critically Endangered", "Endangered" or "Vulnerable" according to the IUCN criteria, with Rivulidae as the family with the largest number of threatened species.

A new species of Ituglanis Costa & Bockmann, 1993 (Siluriformes: Trichomycteridae) endemic to the Tramandaí-Mampituba ecoregion, southern Brazil.

Ituglanis boitata, new species, is described from the rio Tramandaí system and rio Mampituba and Araranguá basins, southern Brazil. This new species is distinguished from congeners with the exception of I. bambui, I. boticario,                       I. paraguassuensis and I. proops by the supraorbital canal of the cephalic laterosensory system interrupted between nasal and frontal sections and the presence of pore s2 (vs. supraorbital canal uninterrupted and pore s2 absent). Ituglanis boitata     differs from these species in osteological characters, measurements and body coloration. Ituglanis boitata presents a              noticeable endemism in the Tramandaí-Mampituba freshwater ecoregion, a recognized biogeographic unit for freshwater fishes including other 22 endemic species. A discussion about the intraspecific variation in the cephalic laterosensory system within Trichomycterinae is also provided.

Taxonomic review of the genus Trichomycterus Valenciennes (Siluriformes: Trichomycteridae) from the laguna dos Patos system, Southern Brazil

The species of the genus Trichomycterus inhabiting the laguna dos Patos system are reviewed and five species are recognized. Trichomycterus tropeiro Ferrer & Malabarba has a restricted range and is endemic to the uppermost portion of the rio das Antas. Trichomycterus balios, n. sp., is distributed in the upper portion of the rio das Antas and rio Caí basins. Trichomycterus diatropoporos, n. sp., is endemic to the rio da Prata basin, a tributary of the rio das Antas. Trichomycterus poikilos, n. sp., is widely distributed in the upper portion of the rio Jacuí basin and tributaries of the rio Taquari-Antas. Trichomycterus brachykechenos, n. sp., is endemic to the upper portion of the rio dos Sinos. The new species are distinguishable from most congeners, except for T. davisi, T. mboycy, T. naipi, T. payaya, T. papilliferus, T. perkos, T. plumbeus, and T. tropeiro by the lower number of pectoral-fin rays (I+5-6) and by the first pectoral-fin ray not prolonged as a filament. Other characters distinguish the new taxa from these eight species. The distribution of the genus in the laguna dos Patos system is discussed and a taxonomic key is provided.

O gênero Trichomycterus é revisado no sistema da laguna dos Patos e cinco espécies são reconhecidas. Trichomycterus tropeiro Ferrer & Malabarba tem distribuição restrita, ocorrendo somente na porção mais superior do rio das Antas. Trichomycterus balios, sp. n., distribui-se na porção superior das bacias dos rios das Antas e Caí. Trichomycterus diatropoporos, sp. n., é endêmica da bacia do rio da Prata, tributário do rio das Antas. Trichomycterus poikilos, sp. n., é amplamente distribuída nos cursos superiores da bacia do rio Jacuí e tributários dos rios Taquari-Antas. Trichomycterus brachykechenos, sp. n., é endêmica do curso superior do rio dos Sinos. As espécies novas distinguem-se de grande parte de seus congêneres pelo baixo número de raios na nadadeira peitoral (I+5-6) e o primeiro raio da nadadeira peitoral não prolongado como filamento, exceto de T. davisi, T. mboycy, T. naipi, T. papilliferus, T. payaya, T. perkos, T. plumbeus e T. tropeiro, distinguindo-se destas por outros caracteres. A distribuição do gênero no sistema da laguna dos Patos é discutida e uma chave taxonômica é fornecida.

Austrolebias paucisquama (Cyprinodontiformes: Rivulidae), a new species of annual killifish from southern Brazil

Austrolebias paucisquama is described from the rio Vacacaí drainage, a tributary to the rio Jacuí, Rio Grande do Sul, Brazil. The new species belongs to the Austrolebias alexandri species-group, by sharing the apomorphic bright blue iridescence and dark gray pectoral fins in males. It is distinguished from other species of this group by having fewer scales around caudal peduncle (12) and fewer dorsal-fin rays in males (17-21). The lack of contact organs on the inner surface of the pectoral fin in males and the color pattern of females - ground color light brownish, sides of body with a variable number of relatively large dark black spots distributed mostly on posterior portion of body - distinguish A. paucisquama from all other species of the genus.

Austrolebias paucisquama, uma nova espécie de peixe anual é descrita da bacia do rio Vacacaí, tributário do rio Jacuí, Rio Grande do Sul, Brasil. A nova espécie pertence ao grupo Austrolebias alexandri, que apresenta duas apomorfias, pontos azuis claros e nadadeiras peitorais cinza escuro nos machos. Distingue-se das outras espécies do grupo pelo reduzido número de escamas ao redor do pedúnculo caudal (12) e pelo menor número de raios na nadadeira dorsal dos machos (17-21). A ausência de órgãos de contato na superfície interior das nadadeiras peitorais nos machos e o padrão de colorido das fêmeas - flancos marrom claro com variável número de pontos pretos relativamente alongados distribuídos principalmente na porção posterior - distinguem A. paucisquama das outras espécies do gênero.