Nivaldo Magalhães Piorski

Alimentação e ecomorfologia de duas espécies de piranhas (Characiformes: Characidae) do lago de Viana, estado do Maranhão, Brasil

Serrasalmus aff. brandtii and Pygocentrus nattereri are two species of piranhas, both common in the Viana Lake, which is formed by the flooding waters of the Pindare River, a tributary of the left bank of the Mearim River. A sample composed of 249 specimens of these species was studied in order to identify diet composition and feeding strategies employed by the two species. The piranhas were captured thrimonthly, during one year from March 1998 to March 1999 using gill and fishing nets of different mesh sizes. The qualitative composition of the diet was analysed through the frequency of occurrence method. The feeding strategies employed by the piranhas were inferred using the graphic method of Costello (1990), modified by Amundsen et al. (1996). The results indicated that fish was the main food item in the stomach contents of the two species, followed by plant material, more in the P. nattereri. Fish and plant material showed different relationships in relation to piranhass length classes. The graphic analysis of the feeding strategies employed by P. nattereri and S. aff. brandtii suggest a generalist habit, wide width niche with strong participation of the within-phenotype component, which indicated that the majority of individuals of these species use several resources simultaneously. A multivariate analysis of the ecomorphological index indicated that the species are discriminated by swimming ability, water column position and relative prey size.

Platydoras brachylecis, a new species of thorny catfish (Siluriformes: Doradidae) from northeastern Brazil

Platydoras brachylecis, new species, is described from coastal drainages of northeastern Brazil (Pindare to Parnaiba rivers), and diagnosed from congeners by the unique combination of: pale yellow to white stripe beginning above orbits, continuing midlaterally on body and onto middle rays of caudal fin; skin in axil of each midlateral thorn without concentration of pigment forming small dark spot, midlateral scutes shallow (depth of 10 th scute 8.8-11.9% of SL), and midlateral scutes on caudal peduncle distinctly separated by strip of skin from middorsal and midventral caudal-peduncle plates. Three additional species of Platydoras are recognized as valid: P. armatulus (lower Orinoco, Amazon and Paraguay-Parana drainages), P. costatus (coastal drainages of Suriname and French Guiana), and P. hancockii (upper Orinoco, Negro, Essequibo and Demerara drainages). The nominal species P. dentatus and P. helicophilus are tentatively treated as junior synonyms of P. costatus. A key to species of Platydoras is provided. Platydoras brachylecis, especie nova, e descrita para as drenagens costeiras do nordeste do Brasil (rios Pindare a Parnaiba) e diagnosticada de suas congeneres pela exclusiva combinacao dos seguintes caracteres: faixa amarelo-palida a branco iniciando acima das orbitas, continuando medio-lateralmente sobre o corpo e atingindo os raios medianos da nadadeira caudal; pele das axilas dos espinhos medio-laterais sem concentracao de pequenas pintas negras; escudos medio-laterais baixos (altura do decimo escudo 8.8-11.9% do comprimento padrao) e escudos medio-laterais do pedunculo caudal distintamente separados das placas medio-dorsais e medio-ventrais da mesma regiao por uma faixa de pele. Mais tres especies de Platydoras sao reconhecidas como validas: P. armatulus (distribuida pelas drenagens do baixo Orinoco, Amazonia e Paraguai-Parana), P. costatus (drenagens costeiras do Suriname e Guiana Francesa) e P. hancockii (drenagens do Negro, Essequibo, Demerara e alto Orinoco). As especies nominais P. dentatus e P. helicophilus sao provisoriamente consideradas sinonimos juniores de P. costatus. Uma chave de identificacao para as especies do genero Platydoras e apresentada.

Invasion of the Indo-Pacific blenny Omobranchus punctatus (Perciformes: Blenniidae) on the Atlantic Coast of Central and South America

We examined 308 specimens of the Indo-Pacific blenniid Omobranchus punctatus deposited in four museum collections, and analyzed data on their collection locations to assess its invasion on the Atlantic coast of Central and South America. This species occurs in shoreline estuarine and marine habitats in the Indo-West Pacific. Previous sampling and recent records in the Tropical West Atlantic from 1930 to 2004 produced 20 records for: Panama, Colombia, Venezuela, Trinidad and Brazil. In this work, we provide data on 17 new records for the Gulfs of Venezuela and Paria in Venezuela, as well as four records for Maranhao and Para states in NE Brazil. The temporal pattern of collections (1930 - 2009) and the proximity of most localities to ports and zones of ship traffic indicate that O. punctatus was initially introduced to the Atlantic by ships travelling from India to Trinidad. Within Brazil the introduction is linked to shipping connected to petroleum platforms. In Maranhao and Para the

A case of albinism in Batrachoides surinamensis (Batrachoidiformes: Batrachoididae) from north-eastern Brazil

This paper reports the occurrence of a specimen of the toadfish Batrachoides surinamensis caught from the Ilha do Maranhao, State of Maranhao, north-eastern Brazil, which exhibited total albinism features.

A dorsal fold in Gymnura micrura (Bloch and Scheneider, 1801) (Chondrichthyes: Gymnuridae)

This paper reports a dorsal fold which is a membranous structure located on the tail of two juvenile butterfly rays, Gymnura micrura (Bloch & Scheneider, 1801), caught through artisanal fishery in the shallow waters of Maranhao State (Brazil).

Near-term embryos in a Pristis pristis (Elasmobranchii: Pristidae) from Brazil

This paper describes the record of a gravid Pristis pristis from the north coast of Maranhão State (Brazil) in May of 2009 by an artisanal vessel. Size, mass and rostrum length of the adult female were estimated at 5000 mm, 750000 g and 1536 mm, respectively. Total length (LT ) of miscarried embryos ranged from 755 to 800 mm and total mass from 890 to 1120 g. Although this is a single record, it indicates that P. pristis births may be taking place during May or coming months and there may be population differences between Central and South America.

Ichthyofauna sampled with tadpoles in northeastern Maranhão state, Brazil

The Neotropic region has high fish diversity associated with freshwater habitats. However, for Maranhao state, most publications on the ichthyofauna concentrate on coastal or estuarine ecosystems. In this study, species of fish were sampled in lentic and lotic habitats in Cerrado areas (Cerradao phytophysiognomy) and in restinga areas (Atlantic Forest phytophysiognomy) in northeastern Maranhao state between January and July 2010. Thirteen species from 10 families and 6 orders were captured. Species richness was highest for the orders Characiformes and Gymnotiformes. Our results are the first records of the ichthyofauna of coastal drainage areas of northeastern Maranhao state, contributing to the understanding of the biodiversity of the Munim and Parnaiba River basins, and suggest the existence of a community that shares elements with those of the Amazon and Caatinga biomes.