Osvaldo T. Oyakawa

Diversidade da ictiofauna do Alto Rio Paraná: composição atual e perspectivas futuras

Langeani, F., Castro, R.M.C., Oyakawa, O.T., Shibatta, O.A., Pavanelli, C.S. & Casatti, L. Ichthyofauna diversity of the upper rio Parana: present composition and future perspectives. Biota Neotrop. Sep/Dez 2007 vol. 7, no. 3 http://www.biotaneotropica.org.br/v7n3/pt/abstract?article+bn03407032007. ISSN 1676-0603. A synthesis concerning fishes from Upper Parana River basin is presented, based on data from fish-collections, literature, and new field samples. Three hundred and ten species, pertaining to 11 orders and 38 families, are referred to the drainage, elevating anterior estimates. Concerning total species, 236 (76.1%) are autochthonous, 67 (21.6%) are allochthonous, and seven (2.3%) are exotic. Principal causes of occurrence of non-native species are: a) dispersal from the Lower Parana, after the construction of Itaipu dam, and b) escapes from aquaculture farms. Most species (65%) are small-sized, having less than 21 cm of length, and the great majority occurs only in headwaters and small streams. One of the best known and most studied in Brazil, Upper Parana ichthyofauna richness is far from reaching actual numbers, considering the exponential elevation of species presented herein. Indeed, in the last years various new species have been described and around 50 other species, already recognized as new, are now under description. The improvement on the knowledge about Upper Parana ichthyofauna is proportional to the number of researchers involved with studies in the area and, unequivocally, reflects recent initiatives stimulating and incrementing taxonomic research, and also improving access to fish collections and to poor or never-sampled areas. However, if we are going to maintain the number of species descriptions per year of last decade, the 50 new species already recognized, will be described only in the next ten years, a period too long. In consequence it is very important that scientific community and grant agencies find and offer initiatives in order to elevate the number of new taxa descriptions per year.

Restricted-Range Fishes and the Conservation of Brazilian Freshwaters

Background Freshwaters are the most threatened ecosystems on earth. Although recent assessments provide data on global priority regions for freshwater conservation, local scale priorities remain unknown. Refining the scale of global biodiversity assessments (both at terrestrial and freshwater realms) and translating these into conservation priorities on the ground remains a major challenge to biodiversity science, and depends directly on species occurrence data of high taxonomic and geographic resolution. Brazil harbors the richest freshwater ichthyofauna in the world, but knowledge on endemic areas and conservation in Brazilian rivers is still scarce. Methodology/Principal Findings Using data on environmental threats and revised species distribution data we detect and delineate 540 small watershed areas harboring 819 restricted-range fishes in Brazil. Many of these areas are already highly threatened, as 159 (29%) watersheds have lost more than 70% of their original vegetation cover, and only 141 (26%) show significant overlap with formally protected areas or indigenous lands. We detected 220 (40%) critical watersheds overlapping hydroelectric dams or showing both poor formal protection and widespread habitat loss; these sites harbor 344 endemic fish species that may face extinction if no conservation action is in place in the near future. Conclusions/Significance We provide the first analysis of site-scale conservation priorities in the richest freshwater ecosystems of the globe. Our results corroborate the hypothesis that freshwater biodiversity has been neglected in former conservation assessments. The study provides a simple and straightforward method for detecting freshwater priority areas based on endemism and threat, and represents a starting point for integrating freshwater and terrestrial conservation in representative and biogeographically consistent site-scale conservation strategies, that may be scaled-up following naturally linked drainage systems. Proper management (e. g. forestry code enforcement, landscape planning) and conservation (e. g. formal protection) of the 540 watersheds detected herein will be decisive in avoiding species extinction in the richest aquatic ecosystems on the planet.

Revision of the Neotropical trahiras of the Hoplias lacerdae species-group (Ostariophysi: Characiformes: Erythrinidae) with descriptions of two new species

Hoplias lacerdae was originally described from the rio Ribeira de Iguape, Iporanga, Sao Paulo State. The Hoplias lacerdae group is defined as containing generally large trahiras with the medial margins of dentaries running parallel to each other and lacking teeth on the basihyal compared to the H. malabaricus group in which the medial margins of the dentaries converge towards the mandibular symphysis and which have teeth on the basihyal. A taxonomic revision of the group based on meristic and morphometric data identified five distinct species: H. lacerdae distributed in the rio Ribeira de Iguape and rio Uruguai; H. intermedius from the rio Sao Francisco, upper rio Parana basin, and rio Doce; H. brasiliensis from rivers of the Atlantic Coastal drainage from the rio Paraguacu to the rio Jequitinhonha; H. australis new species, endemic to the rio Uruguai; and H. curupira new species present in northern South America, including the rios Negro, Trombetas, Tapajos, Xingu, Tocantins and Capim in the Amazon basin, upper rio Orinoco near the rio Casiquiare (Venezuela), and coastal rivers of Guyana and Suriname. A lectotype for Hoplias intermedius and a neotype for H. brasiliensis are designated. Hoplias lacerdae foi descrita originalmente do rio Ribeira de Iguape, Iporanga, Sao Paulo. O grupo Hoplias lacerdae foi definido como um conjunto de especies para abrigar as trairas geralmente de grande porte, com as margens mediais dos dentarios dispostas paralelamente e sem dentes no basi-hial, em oposicao as trairas do grupo Hoplias malabaricus, cujas margens mediais dos dentarios convergem em direcao a sinfise mandibular e possuem dentes no basi-hial. A revisao taxonomica do grupo baseada em dados meristicos e morfometricos identificou cinco especies distintas: Hoplias lacerdae distribuida nos rios Ribeira de Iguape e Uruguai; H. intermedius no rio Sao Francisco, alto rio Parana e rio Doce; H. brasiliensis nos rios costeiros da drenagem Atlântica, desde o rio Paraguacu ate o rio Jequitinhonha; H. australis especie nova, endemica ao rio Uruguai; e H. curupira especie nova no norte da America do Sul, incluindo os rios Negro, Trombetas, Tapajos, Xingu, Tocantins e Capim na bacia Amazonica; alto rio Orinoco proximo ao rio Casiquiare (Venezuela) e rios costeiros da Guiana e Suriname. Sao designados um lectotipo para Hoplias intermedius e um neotipo para H. brasiliensis.

Spatial and Temporal Patterns of Diversity and Distribution of the Upper Juruá River Fish Community (Brazilian Amazon)

We studied spatial and temporal patterns in fish species composition and diversity at the upper Juruá River located in the west Brazilian Amazon. We collected with gillnet 822 fishes belonging to 90 species in the main Juruá River, its tributaries and the floodplain lakes during wet and dry seasons. Fish abundance and species richness were greater in the dry season. During that season, fishes may be concentrated due to the low water level, being caught more easily by gillnets. There has been a trend towards a greater fish biomass caught in lakes. This might be associated with a greater environmental stability as lakes may be less subject to large variations in water level. The fish communities differed between the two seasons and between lakes and the lotic environments (main river and tributaries). Fish species from the family Curimatidae were most abundant in the lakes, while Pimelodus spp. and Hypostomus spp. predominated in the main Juruá River. Seasonal variations in fish communities may be related to differences in the migratory behavior among fish species. Such spatial and temporal patterns influencing fish community structure at the Upper Juruá Extractive Reserve must be accounted for in management and conservation strategies.

Uses of Fish and Game by Inhabitants of an Extractive Reserve (Upper Juruá, Acre, Brazil)

The fishing and hunting performed by inhabitants of the Extractive Reserve of the Upper Juruá, Acre, Brazil was studied, and an ecological analysis on the use of fish and game, including preferences, taboos and medicinal uses, and of fish abundance was made. Research was carried out at the Upper Juruá Extractive Reserve in three visits (1993 and 1994). A total of 143 individuals (101 families) living along the banks of the rivers Juruá, Tejo, Bagé, S. João and Breu were interviewed, and 115 species of fish with set gillnets were collected. Local economic activities included rubber-tapping and small-scale agriculture. Fishing was especially important in the dry season, when cast net and hook and line were used. Hunting and game consumption were intensive in the wet season. Some local rules may be useful as starting points for local management, such as the use of fish diversity through lake management, the use of water level seasonality, hunting periods or quotas, and food taboos. The integration of academic research with indigenous knowledge and demands is important to develop management plans which protect both biological and cultural diversity.

Checklist dos peixes de água doce do Estado de São Paulo, Brasil

The fish species living in the freshwaters of the Sao Paulo state (393) are distributed among four major river basins: upper Parana, Paraiba do Sul, Ribeira de Iguape and a set of small coastal drainages flowing directly into the Atlantic Ocean. Since these river basins drain areas with distinct vegetation types, soils, etc., each one has a different species composition. In the Upper Parana the large Rio Parana and some of its large tributaries (Tiete, Paranapanema, and Grande) contain large species that support commercial fisheries, however, 70 to 80% of the ichthyofauna is composed by small species found in small streams, including those in headwaters where many are endemic. The inventory of the ichthyofauna greatly benefited from three research projects supported by the BIOTA/FAPESP program, but much work remains to be done to collect and describe new species from areas such as deep channels, headwaters and marginal and swampy areas around ponds and man-made lakes and reservoirs. The ichthyofauna of the Sao Paulo State has suffered from deforestation, sewage, damming of rivers for construction of power plants, urbanization, etc., so that 66 species are currently considered threatened at various levels according to the criteria of the International Union for Conservation of Nature and Natural Resources (IUCN).

Isbrueckerichthys epakmos, a new species of loricariid catfish from the rio Ribeira de Iguape basin, Brazil (Teleostei: Siluriformes)

Isbrueckerichthys epakmos, new species, is described from the tributaries of the rio Juquia, rio Ribeira de Iguape basin, Sao Paulo State, Brazil. The new species displays a unique sexual dimorphism. Mature males are distinguished from its congeners by having a well-developed soft fleshy area and a clump of hypertrophied short odontodes directed forward or slightly upward on anterior portion of snout. It is compared with I. duseni and I. alipionis, which occurs sympatrically in the rio Ribeira de Iguape drainage. A key to the species of Isbrueckerichthys is provided.

Rediscovery and redescription of the unusual subterranean characiform Stygichthys typhlops, with notes on its life history

The rediscovery of the enigmatic subterranean characiform Stygichthys typhlops is reported almost a half-century after the collection of the holotype, the only specimen previously known. Thirty-four specimens were collected in two shallow hand-dug wells at the region of the type locality, c. 13 km south-west of the town of Jaíba, Minas Gerais, Brazil. These specimens provide new information on the morphology of this species, and for the first time on its life history. The conservation status of S. typhlops is discussed. The species is severely threatened by habitat loss caused by exploitation of the aquifer.

Taxonomic Study of Hoplias aimara (Valenciennes, 1846) and Hoplias macrophthalmus (Pellegrin, 1907) (Ostariophysi, Characiformes, Erythrinidae)

Abstract The taxonomy of the nominal species of giant trahiras Hoplias aimara (Valenciennes, 1846) and Hoplias macrophthalmus (Pellegrin, 1907), both described from Cayenne (French Guiana), was evaluated to determine whether they constitute distinct forms and to determine the geographic distribution of the recognized species. A total of 200 specimens were examined (30–624 mm standard length). Analysis of meristic and morphometric data resulted in the recognition of a single species. Study of the type-specimens revealed that both species names, H. aimara and H. macrophthalmus, refer to the same taxon. According to the Principle of Priority of the International Code of Zoological Nomenclature the name Hoplias aimara has precedence. This species is distinguished from congeners by the presence of a vertically-elongate dark spot on the median portion of the opercular membrane and by the absence of the accessory ectopterygoid. Hoplias aimara occurs in the drainages of Rio Tocantins, Rio Xingu, Rio Tapajós, Rio Jarí, and Rio Trombetas, in coastal drainages of the Guyanas, Suriname, and state of Amapá, Brazil. In the Río Orinoco basin, the species occurs only in the Río Caroní and rivers to the east of this drainage. Literature records of Hoplias aimara for the Rio Purus and upper Río Orinoco were based on misidentifications. This pattern of geographic distribution of Hoplias aimara in rivers of the Guyanas and Brazilian Shields also occurs in other Neotropical species of fishes.

Two new species of the catfish genus Trichomycterus (Siluriformes: Trichomycteridae) from the rio Ribeira de Iguape Basin, southeastern Brazil

Duas especies novas de Trichomycterus da bacia do rio Ribeira de Iguape sao descritas. Trichomycterus tupinamba difere das demais especies de Trichomycterinae por apresentar o primeiro raio da nadadeira peitoral nao prolongado como um filamento, nadadeira caudal truncada com margens levemente arredondadas, dois poros supraorbitais s6 contra-laterais, olhos orientados dorsalmente, boca subterminal, abertura anal e urogenital no meio do espaco entre a margem da nadadeira pelvica e a origem da nadadeira anal, uma mancha escura na base dos barbilhoes nasais, uma linha longitudinal mediana formada por manchas escuras enfileiradas do operculo ate proximo da nadadeira caudal, largura da cintura peitoral 13.1-17.7 % do comprimento padrao e altura do pedunculo caudal 8.7-10.3 % do comprimento padrao. Trichomycterus jacupiranga distingue-se das demais especies de Trichomycterinae por apresentar o primeiro raio da nadadeira peitoral prolongado em um curto filamento, um poro supraorbital s6 fusionado, nadadeira pelvica cobrindo as aberturas anal e urogenital, aberturas anal e urogenital mais proximas da origem da nadadeira anal que da base da nadadeira pelvica, nadadeira caudal truncada com margens levemente arredondadas e pelas caracteristicas morfometricas: comprimento da cabeca 20.7-22.4 % do comprimento padrao, comprimento pre-anal 57.1-70.9 % do comprimento padrao, largura da cintura peitoral 17.4-20.6 % do comprimento padrao, comprimento do tronco 33.6-37.5 % do comprimento padrao, comprimento da nadadeira peitoral 16.8-22.7 % do comprimento padrao, comprimento da base da nadadeira dorsal 12.8-14.1 % do comprimento padrao, comprimento da base da nadadeira anal 8.4-10.8 % do comprimento padrao, largura da cabeca 90.6-104.6 % do comprimento da cabeca, comprimento do focinho 40.0-46.9 % do comprimento da cabeca, largura da boca 27.0-37.3 % do comprimento da cabeca e diâmetro do olho 10.4-16.5 % do comprimento da cabeca. Distribuicao, caracteristicas diagnosticas e dados ecologicos sao apresentados para as duas especies.