Melosira (Diatomeae) taxa from the Iguaçu River in southern Brazil

Abstract

The study of the genus Melosira in plankton samples from the lower Iguaçu River revealed the presence of four taxa: Melosira undulata (Ehrenberg) Kützing var. undulata, M. undulata var. normanni Arnott, M. varians C. Agardh and M. muscigena Iwahashi. We present illustrations of the frustules using light microscopy (LM), descriptions, and comments about the morphology of the four taxa. The analysis of Melosira muscigena under scanning electron microscopy revealed unprecedented details of the ultrastructure, such as the shape and distribution of the rimoportulae at the valve mantle. This is the first record of Melosira undulata var. undulata and the second of M. muscigena in Brazil.

Centric diatom diversity in the lower part of the Southern Bug river (Ukraine): the transitional zone at Mykolaiv city

“…Common species for freshwaters in streams and lakes, as well as in slightly brackish waters, oligotrophic, eutrophic to dystrophic or polluted environments ( Nardelli et al 2016 ; Hofmann et al 2018 ). Taxon has preferences of alkaline conditions (pH 7‒8.5), with moderate oxygen, regularly found in humid environments, requiring periodically high levels of nitrogen ( Soltanpour-Gargari et al 2011 ).…”

“…Based on the results above, indicator species for eutrophication in the coastal area of Black Sea waters, which are entering the estuary and then move upstream into the Southern Bug River, were identified. From the investigated taxa the following have been reported as tolerant to nutrient pollution: Aulacoseira subarctica , Cyclotella atomus , C. choctawhatcheeana , Cyclostephanos dubius , Melosira varians , Skeletonema subsalsum , Stephanodiscus hantzschii , S. minutulus ( Hasle and Evensen 1975 ; Van Dam et al 1994 ; Bradbury et al 2002 ; Chris et al 2003 ; Sarno et al 2005 ; Yang et al 2005 ; Jaanus et al 2009 ; Kirilova et al 2010 ; Höglander et al 2013 ; Lowe 2015 ; Reavie and Kireta 2015 ; Burge and Edlund 2016 ; Nardelli et al 2016 ; Hofmann et al 2018 ). Therefore, it is not surprising, that all of them were recorded at Mykolaiv city during different sampling studies and only some of them sporadically at each site.…”

“…Berlin, Germany, see Geissler and Kies 2003), Russia (Genkal et al 2020), Asia (Iran), North America (Canada, USA), Africa (Egypt, RSA); Adriatic, Aral, Azov, Baltic, Barents, Black, Caspian, Kara, Mediterranean, North and Red Seas, and throughout North America (Stoermer and Julius 2003). It is also very common in Brazilian waters (Stoermer and Julius 2003;Tremarin et al 2009;Nardelli et al 2016 Morphological description. Frustule cylindrical, valve face flat with randomly located areolae, diameter is 13.2-14.4 μm (Fig.…”