The skeletal muscles of the dorsolateral region of the head of the Nematogenyidae and representatives of the all major clades of the Trichomycteridae are described and illustrated. A hypothesis on the phylogenetic relationships among these taxa exclusively based on the surveyed musculature is presented. The single most parsimonious cladogram obtained from the phylogenetic analysis of the 36 myological characters gathered and 35 terminal-taxa mostly agrees with the previous hypotheses of trichomycterid intrarelationships. The Copionodontinae and Trichogeninae form a monophyletic lineage that is the sistergroup to all remaining trichomycterids. The monophyly of the clades formed by Glanapteryginae plus Sarcoglanidinae; Stegophilinae plus Tridentinae plus Vandelliinae; and the assemblage comprising all of these five subfamilies (TSVSG clade) is corroborated. Two of our findings are, however, discordant with the previous prevailing hypotheses: the sister-group relationship among Tridentinae and Stegophilinae and the monophyly of the Trichomycterinae lato sensu, i.e., including the genera Scleronema and Ituglanis. In addition, the previously proposed osteological synapomorphies supporting the close affinities of Scleronema and Ituglanis with the TSVSG clade were revised, revealing that they are either invalid or ambiguous. Most of the synapomorphies herein proposed are homoplasy-free, with some of them corroborating the monophyly of weakly-supported groups, such as Stegophilinae.Os músculos esqueléticos da região dorsolateral da cabeça de Nematogenyidae e de representantes de todos os maiores clados de Trichomycteridae são descritos e ilustrados. Uma hipótese das relações filogenéticas entre estes táxons, baseada exclusivamente na musculatura estudada, é apresentada. O único cladograma mais parcimonioso obtido da análise filogenética dos 36 caracteres miológicos levantados e 35 táxons-terminais concorda com a maior parte das hipóteses anteriores de relações entre os tricomicterídeos. Copionodontinae e Trichogeninae formam uma linhagem monofilética que é grupo-irmã de todos os demais tricomicterídeos. O monofiletismo dos clados formados por Glanapteryginae mais Sarcoglanidinae; Stegophilinae mais Tridentinae mais Vandelliinae; e do agrupamento incluindo estas cinco subfamílias (clado TSVSG) é corroborado. Duas de nossas descobertas são, entretanto, discordantes com relação às hipóteses anteriores mais aceitas: a relação de grupo-irmão entre Tridentinae e Stegophilinae e o monofiletismo de Trichomycterinae lato sensu, i.e., incluindo os gêneros Scleronema e Ituglanis. Além disso, as sinapomorfias osteológicas previamente propostas suportando as relações de afinidade de Scleronema e Ituglanis com o clado TSVSG foram revisadas, revelando serem inválidas ou ambíguas. A maior parte das sinapomorfias aqui propostas são livres de homoplasias, com algumas delas corroborando o monofiletismo de grupos fracamente suportados, tais como o da subfamília Stegophilinae.

Foram amostrados 17 trechos de riachos com 100 m de extensão, todos de ordem igual ou menor a três, ao longo de ambas as margens do canal principal do Rio Paranapanema, SP e PR. O ponto médio de cada trecho foi georreferenciado via satélite com receptor GPS e o uso de metodologia padronizada de coleta de dados ambientais e peixes (baseada principalmente na pesca elétrica), possibilitou a obtenção das seguintes informações em cada local: 1) composição taxonômica da ictiofauna e contribuição, em termos de número de indivíduos e biomassa, de cada espécie para a ictiofauna local como um todo; 2) documentação fotográfica de espécimes representativos de cada espécie coletada com sua coloração natural; 3) descrição de cada ambiente coletado, com ilustrações fotográficas coloridas, e seus principais parâmetros bióticos e abióticos. No total foram coletados 3.683 exemplares, pertencentes a seis ordens, 16 famílias, 37 gêneros e 52 espécies, com biomassa total de 16,8 kg. Das espécies coletadas, aproximadamente 36% pertencem a ordem Siluriformes, 36% a Characiformes, 11% a Gymnotiformes, 10% a Perciformes, 4% a Cyprinodontiformes e 2% a Synbranchiformes. As espécies mais abundantes em termos de número de indivíduos foram Astyanax altiparanae (15,2%) e Astyanax sp. 1 (12,3%); aquelas com maior biomassa foram A. altiparanae (28%) e Geophagus brasiliensis (13%). A composição da ictiocenose em termos de abundância e biomassa por família indica a predominância expressiva de Characidae, seguida por Loricariidae, Pimelodidae e Cichlidae. Dentre os trechos amostrados, o trecho 14 (24 espécies) e o 13 (cinco espécies), apresentaram a maior e a menor riqueza em espécies, respectivamente, coincidindo com os valores obtidos para o índice de diversidade específica de Shannon-Wienner (H´= 0,99 e 0,32, respectivamente). A riqueza média encontrada foi de 11 espécies por trecho de riacho. Na estimativa de riqueza por extrapolação para o conjunto total de riachos amostrados na bacia do rio Paranapanema, obtivemos um valor de 69 espécies (erro padrão igual a quatro) indicando ser necessário um esforço amostral adicional moderado para atingir a assíntota da curva. Das 52 espécies coletadas, oito (aproximadamente 15% do total) são seguramente novas, cinco (aproximadamente 10% do total) possuem “status” taxonômico ainda indefinido, enquanto outras três (aproximadamente 6% do total) são espécies introduzidas. Analisando a estrutura trófica e espacial da ictiocenose estudada, as 10 espécies numericamente dominantes nos riachos estudados dividem-se, em ordem decrescente de importância numérica, em quatro guildas: onívoros nectônicos; invertívoros bentônicos; perifitívoros; e onívoros bentônicos. Uma chave de identificação para todas as espécies de peixes coletadas durante este estudo é fornecida ao final deste trabalho.

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Eighteen 100 m long streams stretches, none of an order higher than three, were sampled in three tributaries (six stream stretches sampled in each one) of the left margin of the main channel of Rio Grande (Rios Turvo, Pardo and Sapucaí) in the State of São Paulo, southeastern Brazil. Each stream stretch had its midpoint located with a GPS satellite receiver and had its fish fauna sampled via a standardized environmental data and fish collection methodology (primarily utilizing electrofishing) with the aim of providing the following information about each stream: 1) the taxonomic composition of the fish fauna and the contribution of each species in that stream in terms of both number of individuals and biomass; 2) a photographic documentation of the live coloration of representative specimens of each collected species; and 3) the description of each sampled environment, with colored photographic illustrations and details of the main biotic and abiotic parameters. Overall 3,070 fishes were collected, belonging to six orders, 18 families, 44 genera, and 64 species, with a total biomass of 14.3 kg. Of the collected species, approximately 50% were Characiformes, 26.5% Siluriformes, 11% Perciformes, 6% Gymnotiformes, 5% Cyprinodontiformes, and 1.5% Synbranchiformes. The most abundant species in terms of total number of individuals were Astyanax altiparanae (17.4%) and Hypostomus ancistroides (9%); the species with the largest biomasses were Astyanax altiparanae (35%) and Geophagus brasiliensis (9%). In terms of abundance and biomass collected for each family, the Characidae was clearly the predominant family followed by the Loricariidae, and Cichlidae. Among the sampled stream stretches, locality SG6 with 26 species and locality PG4 with three species yielded the highest and lowest richness in terms of species numbers, respectively. This coincides with the values obtained for the ShannonWiener index of specific diversity (H´ = 1.08 and 0.26, respectively). The median species richness for all streams stretches was 12. In the species richness estimate by extrapolation for all 18 sampled stream stretches, a value of 93 species was obtained (with a standard error of three) indicating the need for an additional moderate sampling effort to reach the asymptote of the curve. Of the 64 collected species, four (approximately 6% of the total) are clearly new to science and seven other species (approximately 11% of the total) are of indefinite taxonomic status and require further analysis. Two of the captured species are certainly introduced (approximately 3% of the total). Analysis of the trophic and spatial structure of the studied fish fauna indicates that the 10 numerically dominant species in the sampled streams can be grouped, based on published data, into five guilds that are in decreasing order of numeric importance: nektonic omnivores; benthic invertivores; periphytovores; algivores and benthic omnivores. An identification key for all the species of fish collected during this study is provided.

Rhamdella cainguae, a new species of the family Heptapteridae is described from the Arroyo Cuña-Pirú, a tributary of the Río Paraná, in the subtropical forest of Misiones, northeastern Argentina. The presence of a large differentiated ovoid area on the supraorbital laterosensory canal along the frontal-sphenotic boundary, delimited by the slender dorsal walls of the bones, and with no foramen for a laterosensory branch, is an autapomorphy for R. cainguae. A detailed description of the skeleton and laterosensory system of R. cainguae is provided. The genus Rhamdella is rediagnosed on the basis of three autapomorphies: a very large opening in the frontal for the exit of the s6 (epiphyseal) branch of the supraorbital laterosensory canal (reversed in R. rusbyi), a large optic foramen, and a dark stripe along the lateral surface of the body (reversed in R. rusbyi). Rhamdella is considered to be the sister group of a large heptapterid clade composed of the Nemuroglanis sub-clade plus the genera Brachyglanis, Gladioglanis, Leptorhamdia, and Myoglanis. Rhamdella is herein restricted to five valid species: R. aymarae, R. cainguae, R. eriarcha, R. longiuscula, and R. rusbyi. A sister group relationship between R. aymarae and R. rusbyi is supported by three synapomorphies. Rhamdella cainguae shares 12 apomorphic features with R. eriarcha and R. longiuscula.

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Systematists have come under a barrage of criticism because of the alleged inadequacy of the 'traditional' taxonomic paradigm to curb the 'biodiversity crisis' and expeditiously make available the products of systematic research-usually species names-to the professional biological 'user' community (including ecologists, physiologists, population geneticists, and conservationists). The accusations leveled on systematists range from being 'slow' to 'incapable' of furnishing these products at a rate considered (by users) appropriate, especially given that the professional systematic community is portrayed as being in stark decline while operating in a quickly deteriorating natural world. Some of the critics have proposed solutions to this 'taxonomic impediment' in the form of a triumvirate adjoining a unitary taxonomic cyberstructure + automated DNA barcoding + molecular phylogeny, which we consider to be nothing but a threefold miopia; one critic has even gone as far as to suggest that biologists who need systematists can circumvent this dependency by 'doing systematics themselves'. The application of a quick-fix, 'automatedpragmatist' model is antithetical to a science endowed with a strong epistemological and theoretical foundation. We view the current propaganda in favor of automation and pragmatism in systematics as a distraction from the real issues confronting systematists, who must do more to impede the current trend that has 'marginalized' organismal biology in general. Simply increasing the rate of species descriptions, as suggested by critics, will not ameliorate the 'crisis'-taxa that correspond to incorrect hypotheses of biological entities (i.e. that are not monophyletic) will compromise the reliability of systematic information. Systematists must therefore provide more than 'binomials'-they must strive to produce vigorous hypotheses of comparative biology that are historical and theory-rich in order to augment the general reference system that is so critical to research in other biological sciences and conservation.