Taxonomia do gênero Pinnularia na região oeste paraense

Abstract

Aiming to deepen studies on diatoms in the Tapajós river basin, the present study aimed to carry out a taxonomic survey and observe the high species richness of the genus Pinnularia in planktonic and benthic samples of the Tapajós river, Jurucuí lake, Verde lake, Tapari lake, Preto lake and Arapiuns river, environments considered to have clear waters. The planktonic samples were followed with a 20 μm plankton net, through vertical and horizontal trawling, while the benthic material was collected with a core-type sampler, in the period of 2016 (october and december), 2018 (december), 2019 (april, may and september) and 2021 (march, april and june), totaling 11 samples that were stored in 100 mL bottles and accompanied with Transeau solution. During the collections, measurements of temperature, electrical conductivity, oxygen, pH, depth and water transparency were performed. For morphological analysis in optical microscopy, the samples were observed during the process of presenting and mounting permanent slides. 38 taxa were found, of which 28 species, seven varieties and three conferatum, including Pinnularia acuminata, Pinnularia subcapitata, Pinnularia latevittata, Pinnularia rostratissima var. superventricosa constitute the first citation for the state of Pará and Pinnularia esoxiformis constitutes the first citation for Brazil. Regarding the richness of the studied points, Tapari lake was the one that presented the highest number of taxa, with 16 species recorded and the Tapajós river was the one that presented the lowest number of taxa, with only two species registered. The results obtained with the accomplishment of this study for the increase of the taxonomic knowledge and valuable information regarding the high species richness of the family Pinnulariaceae for the region, being, in this way, relevant for the accomplishment of new researches.