Navegando por Autor "ALMEIDA, Mauricio Pinto de"

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Acesso aberto (Open Access)
Diet of the freshwater stingray Potamotrygon motoro (Chondrichthyes: Potamotrygonidae) on Marajó Island (Pará, Brazil)
(2010-02) ALMEIDA, Mauricio Pinto de; LINS, Paulo Marcelo de Oliveira; CHARVET, Patrícia; BARTHEM, Ronaldo Borges
The stomach contents of 137 examples of Potamotrygon motoro caught in 3 locations (Muaná, Afuá and Lake Arari) on Marajó Island were analysed. The values of the Index of Relative Importance (IRI) and its respective percentage (%IRI) were calculated. The level of repletion 1 (¼ full) was the most representative for both sexes, as well as for immature and mature specimens. Most of the food items found were well-digested. The food items identification indicated the presence of 15 orders, including insects, mollusks, crustaceans, annelids and fish. Differences in diet were observed among the locations studied when comparing %IRI, crustaceans being the most preferred in Afuá, fish in Lake Arari and mollusks in Muaná.
Acesso aberto (Open Access)
História natural das raias de água doce (Chondrichthyes: Potamotrygonidae) na Ilha de Marajó (Pará- Brasil)
(Universidade Federal do Pará, 2008) ALMEIDA, Mauricio Pinto de; BARTHEM, Ronaldo Borges; http://lattes.cnpq.br/4192105831997326
The present study was on the natural history of freshwater stingrays species (Potamotrygonidae) of the Marajó Island. It was carried out in four sampling points (Afuá, Lago Arari, Muaná and Soure) in dry, rainy and transition seasons, in 2005 throughout 2007. Five species were captured in this area, Plesiotrygon iwamae, Paratrygon aiereba, Potamotrygon motoro, Potamotrygon orbignyi and Potamotrygon scobina and two other new species, presently in description. Data on the Potamotrygonidae family composition and distribution were obtained, such as frequency of occurrence, biomass and fishery gear selectivity. Data on the reproduction and feeding of the species were described for this region, with emphasis on Potamotrygon motoro.
Acesso aberto (Open Access)
Pesca, policromatismo e aspectos sistemáticos de Potamotrygon scobina Garmam, 1913 (Chondrichthyes : Potamotrygonidae) da região da Ilha de Colares - Baía de Marajó - Pará
(Universidade Federal do Pará, 2003-03-07) ALMEIDA, Mauricio Pinto de; BARTHEM, Ronaldo Borges; http://lattes.cnpq.br/4192105831997326
The present study included specimens of the Family Potamotrygonidae, the only one among elasmobranchs formed entirely by freshwater representatives. This research was developed in the estuarine region of the Marajó Bay, in the island of Colares, during the months of May, August, October and December of 2000, December of 2001 and March of 2002. Sampling included the genera Plesiotrygon, Potamottygon, Paratrygon and a fourth undescribed genus, totalizing 723 captured specimens. Frequency of occurrence and biomass results indicated a predominance of the genus Potamotrygon especially of the species P. scobina in this area. Fishing gear utilized influenced the size of the stingrays captured. Specific observations related to the dorsal color patterns, size and sexual distribution of the species P. scobina were made. Results of multivariate statistical analysis and molecular genetics indicated that dorsal color patterns as currently employed in distinguishling morphotypes in fact did not indicate separate species and a single group was formed. Three previously undescribed dorsal color patterns for sub-adults / adults and two new patterns for juvenile specimens were identified for P. scobina. External characters analyzed for this species presented a wide variation in form, number, size and structure disposition that were more evident in sub-adults / adults. In this region, freshwater stingrays are routinely captured mainly for food and for medical and ornamental purposes. The conservation of freshwater stingrays species requires further knowledge about their biology and taxonomy in order to follow-up its exploitation and perhaps indicate management procedures.
Acesso aberto (Open Access)
A test of the utility of DNA barcoding in the radiation of the freshwater stingray genus Potamotrygon (Potamotrygonidae, Myliobatiformes)
(2008) RIBEIRO, Daniel Toffoli; HRBEK, Tomas; ARAÚJO, Maria Lúcia Góes de; ALMEIDA, Mauricio Pinto de; CHARVET-ALMEIDA, Patricia; FARIAS, Izeni Pires
DNA barcoding is a recently proposed global standard in taxonomy based on DNA sequences. The two main goals of DNA barcoding methodology are assignment of specimens to a species and discovery of new species. There are two main underlying assumptions: i) reciprocal monophyly of species, and ii) intraspecific divergence is always less than interspecific divergence. Here we present a phylogenetic analysis of the family Potamotrygonidae based on mitochondrial cytochrome c oxidase I gene, sampling 10 out of the 18 to 20 valid species including two non-described species. Potamotrygonidae systematics is still not fully resolved with several still-to-be-described species while some other species are difficult to delimit due to overlap in morphological characters and because of sharing a complex color patterns. Our results suggest that the family passed through a process of rapid speciation and that the species Potamotrygon motoro, P. scobina, and P. orbignyi share haplotypes extensively. Our results suggest that systems of identification of specimens based on DNA sequences, together with morphological and/or ecological characters, can aid taxonomic studies, but delimitation of new species based on threshold values of genetic distances are overly simplistic and misleading.