Micrasterias C.Agardh Ex Ralfsemend. Skaloud, Nemjová, Veselá, Cerna & Neustupa(Desmidiaceae, Conjugatophyceae) da região metropolitana de Salvador, Bahia, Brasil

Abstract

(Micrasterias C.Agardh ex Ralfs emend. Škaloud, Nemjová, Veselá, Cerna & Neustupa (Desmidiaceae, Conjugatophyceae) of Metropolitan Region of Salvador, Bahia, Brazil).This work is a contribution to the knowledge of Micrasterias biodiversity in metropolitan region of Salvador (MRS). The floristic survey was based on 269 samples collected from 13 municipalities of the MRS, of which 133 came from samples deposited in Herbarium (HUEFS), collected from 2007 to 2009, and 136 collected in 2014-2015, specifically for this study. All sampling sites were georeferenced. Planktonic samples were collected with a plankton net with 20μm mesh while periphytic samples by squeezing submerged parts of aquatic macrophytes. The floristic similarity between the municipalities was based on Similarity Score Jaccard and construction of dendrogram based on the group average (UPGMA). In addition to a dichotomous key to identify the species in the MRS, the following data are provided for each taxon: reference to the original description, description, geographic distribution in Brazil, comments and illustrations. In MRSMicrasterias was represented by 31 taxa distribuited in 20 species, 12 varieties that are not the typical of their respective species and two taxonomic forms also not typical, however, of their respective varieties. Among the taxa identified M. furcata var. dichotoma, M. novae-terrae and M. rotata var. rotata f. evoluta are cited for the first time to Brazil, and M. radians is a new addition to the Bahia State. Among all municipalities studied, only Madre de Deus and Simões Filho had no representative of Micrasterias while nine municipalities had the first record of genus.The taxa greater absolute frequency of occurrence in MRS were Micrasteriaslaticeps var. laticeps (969 specimens), M. truncata var. pusilla (858), M. pinnatifida var. pinnatifida (838) and M. radians (546).Micrasterias laticeps var. laticeps and M. pinnatifida var. pinnatifida had wide geographical distribution in RMS, and also displayed a great morphological variation. According to the overall frequency of occurrence of taxa studied it was found that most were rare (71%) and M. pinnatifida var. pinnatifidawas the only taxon considered frequent in the study area. It was observed that the wealth of Micrasterias depending on the location of the water body, thus, the number of taxa was higher in water bodies located in the coastal strip (28) than in those located in the interior (23). Camaçari was the municipality with the highest taxonomic richness, registering 83.8% of the taxa present in the MRS, followed by Mata de São João (61.3%) and Vera Cruz (58%). The municipalities that had the highest similarity taxonomic were Candeias and São Sebastião do Passé (90%), followed by Camaçari and Mata de São João (75%). The results of this study show that although strong environmental pressure, the MRS is still holds a great biodiversity, but demand for its preservation, actions to mitigate effects of pollution of water bodies present in the area.