Biological index based on epiphytic diatom assemblages is more restrictive than the physicochemical index in water assessment on an Amazon floodplain, Brazil.

Canadian Water Quality Index (CWQI) provides protection for freshwater life promoting healthy ecosystems and safeguarding human health. Biological Diatom Index (BDI) was developed to indicate the ecological status and water quality of freshwater systems. This paper evaluates the relations between the two different indices. During rising and falling, water samples were taken in the Curuai Floodplain, Brazil. CWQI was calculated using 14 physicochemical parameters and 1 microbiological parameter. The limits were established according to freshwater quality conditions and standards based on water use classes 1 and 2 determined in CONAMA 357 legislation and British Columbia. Canadian Water Quality Index categorization ranged from "marginal" to "excellent," most sampling units were "good" (71%), followed by "fair" (12%) and "excellent" (12%) water quality. Total phosphorus (38 times), chlorophyll a (20), dissolved oxygen (10), and total organic carbon (10) were the parameters that presented the most non-compliance values. Encyonema silesiacum (14%), Gomphonema parvulum (13%), and Navicula cryptotenella (12%) were the main taxa in the rising period, while G. lagenula, E. silesiacum, and Fragilaria capucina were the main taxa during the falling period. BDI ranges from I to V water quality classes. We observed "poor" to "very good" ecological status, with most sampling units "moderate" (52%) and "good" (29%). Water quality for class 2 was better than water quality for class 1, as the limits of the parameters evaluated were more restrictive in class 1 than in class 2 and the predominant uses of water require a higher degree of water purity. The biological index based on diatoms was the most restrictive index whose water classes and categorizations have shown an ecological status that could threaten the protection of aquatic communities on the Curuai floodplain. We suggest the combined use of both indices-physicochemical and biological for water quality assessment in this type of environment.

The genus Pinnularia (Bacillariophyta, Pinnulariaceae) from Lago dos Tigres, Britânia, Goiás, Brazil / O gênero Pinnularia (Bacillariophyta, Pinnulariaceae) do Lago dos Tigres, Britânia, Goiás, Brasil

Studies of the genus Pinnularia Ehrenb. are only incipient in central-western Brazil, especially in Goiás. Only 20 of the 170 taxa known from Brazil were recorded in this state until now. A taxonomic study of Pinnularia from Lago dos Tigres (Tocantins-Araguaia River Basin) recorded 20 specific and infraspecific taxa, distributed in 17 species, including P. instabilis whose lectotype is designated here. Only P. meridiana var. meridiana was previously recorded in aquatic systems of the state. Eighteen taxa are newly recorded for Goiás, and one is the first record in Brazil. The Pinnularia flora from Lago dos Tigres contains nine taxa in common with the Amazon River Basin flora, and seven other taxa that occur elsewhere in the Paraná River Basin.

O gênero Pinnularia Ehrenb. é incipientemente estudado na região Centro-Oeste brasileira, especialmente em Goiás. Somente 20 de 170 táxons conhecidos no Brasil foram registrados nesse estado até agora. Nesse estudo, objetivou-se a realização de estudos taxonômicos de Pinnularia do Lago dos Tigres (Bacia Tocantins-Araguaia). Vinte táxons em nível específico e infraespecífico, distribuídos em 17 espécies, foram observados e caracterizados aqui, incluindo P. instabilis cujo lectótipo foi designado aqui. Somente P. meridiana var. meridiana foi primeiramente registrada em sistemas aquáticos do estado. Dezoito táxons constituíram citações pioneiras para o estado de Goiás e um foi o primeiro registro de ocorrência para o Brasil. A flora de Pinnularia do Lago dos Tigres apresentou nove táxons comuns com a Bacia Amazônica e outras sete foram comuns è Bacia do Paraná.

Typification and taxonomic status re-evaluation of 15 taxon names within the species complex Cymbellaaffinis/tumidula/turgidula (Cymbellaceae, Bacillariophyta).

Specimens belonging to the Cymbellaaffinis / Cymbellatumidula / Cymbellaturgidula species complex have many taxonomic problems, due to their high morphological variability and lack of type designations. Fifteen taxon names of this complex, distributed in five species, were re-evaluated concerning their taxonomic status, and lectotypified based on original material. In addition to light microscopy, some material was analyzed by electron microscopy. Four new combinations are proposed in order to reposition infraspecific taxa.

Diatoms from Brazil: the taxa recorded by Christian Gottfried Ehrenberg.

The flora of diatoms from Brazil has been studied by several authors from the beginning of the 19(th) up to now. Some of the old lists and descriptions are unknown or have been ignored by Brazilian researchers and the situation of the names cited was not assessed. Here we compiled a list of 101 taxa of diatoms from Brazil registered by Christian Gottfried Ehrenberg during the 19(th) century. We checked the current nomenclatural status of those taxa and lectotypified species from Brazil described by this author. For this, we accessed the Ehrenberg collection in the Museum für Naturkunde, Berlin, Germany, where 11 samples from Brazil studied by Ehrenberg are housed and published in different papers. Using these samples, we found 101 taxa (specific and infraspecific) published by Ehrenberg from Brazil. Five species (Eunotia bidens Ehrenb., Eunotia depressa Ehrenb., Eunotia elephas Ehrenb., Pinnularia microstauron Ehrenb., and Terpsinoe brasiliensis Ehrenb.) were new descriptions and were lectotypified here. The other species cited for Brazil were described initially from other places. However, 23 names were invalid and one illegitimate.