New or otherwise interesting desmid taxa from the Bangweulu region (Zambia). 1. Genera Micrasterias and Allorgeia (Desmidiales)

Background and aims - As for desmids, the Bangweulu wetlands in Zambia have turned out to belong to the most species-rich areas in Africa. Because of the scarce desmid literature dealing with those wetlands the present authors visited the region in question intending to increase our knowledge of African endemic species. Methods - Samples were collected from Lake Bangweulu and adjacent swamps as well as from Lake WakaWaka, a small isolated lake c. 150 km south-east of it. Collection was by squeezing submerged plant material or using a plankton net. Samples were partly immediately fixed for drawing desmid taxa later on, partly taken home alive for photographing and possible culturing. Key results -Two taxa are described as new to science: Micrasterias denboeri and M. radians var. cruxoides. M. truncata var. africana is raised to species level. Two varieties of M. tropica, i.e. var. elegans and var. elongata are split off as separate species. M. tropica var. crassa is recombined to M. robusta var. crassa. The asymmetric taxa M. sudanensis and Allorgeia incredibilis are discussed for their possible relationships. Conclusions - Most of the taxa discussed may be considered African endemics. Some of them, i.e. M. denboeri, M. sudanensis and Allorgeia incredibilis, presumably are even confined to the tropical central part of Africa. Most of the tropical records of M. crux-melitensis in literature probably have to be considered small forms of M. radians rather than to refer to European-North American M. crux-melitensis

Distributional patterns in some neotropical desmid species (Algae, Chlorophyta) in relation to migratory bird routes

La discussion est basée sur des échantillonnages réalisés par les auteurs en Colombie, et sur les données de la littérature. Des différences marquées entre la flore des Desmidiées tropicales d'Amérique Centrale et de l'ouest de L'Amérique du Sud, d'une part, et celle des bassins Orénoque-Amazone, d'autre part, suggèrent que les Andes limitent la distribution des algues d'eau douce en étant une barrière aux migrations des oiseaux aquatiques qui en sont les vecteurs potentiels. (Résumé d'auteur

Genera Euastrum Ehrenberg ex Ralfs and Micrasterias C.Agardh (Conjugatophyceae-Desmidiaceae) from two Amazon black water environments (Manaus,Amazonas-Brazil)

An investigation of genera Euastrum Ehrenberg ex Ralfs and Micrasterias C.Agardh from an Amazon floodplain lake of the Negro river Basin was undertaken. The samples were collected using a plankton net in four stations on the Tupe Lake and one station near a lake on the Negro river. The species were identified and described on the basis of morphological and morphometrical characteristics. A total of 12 species were identified, five species of Euastrum genus (E. evolutum var. perornatum; E. gemmatum var. monocyclum; E. ornans; E. sinuosum; E. spinulosum), and seven of Micrasterias genus (M. borgei; M. radiata var. brasiliensis; M. torreyi; M. laticeps var. acuminata; M. mahabuleshwarensis var. amazonensis; M. rotata var. rotata; M. siolii). All species, except M. radiata Hassal var. brasiliensis Grönblad, were found in the Negro river; on the other hand, only seven species were found in the Tupé lake, three of Euastrum and four of Micrasterias.Foi realizado um inventário das espécies dos gêneros Euastrum Ehrenberg ex Ralfs e Micrasterias C.Agardh de dois ambientes de águas pretas do município de Manaus, um lago de inundação (lago Tupé), e o rio Negro. As coletas foram realizadas com rede de plâncton em quatro estações no lago e uma no rio Negro, situada próxima ao lago. Um total de 93 amostras foi analisado, coletadas em escala mensal no período de março de 2002 a outubro de 2003. As espécies foram descritas e ilustradas com base na sua morfologia e morfometria. Um total de 12 espécies foi identificado, sendo cinco do gênero Euastrum (E. evolutum var. perornatum; E. gemmatum var. monocyclum; E. ornans; E. sinuosum e E. spinulosum), e sete do gênero Micrasterias (M. borgei; M. radiata var. brasiliensis; M. torreyi; M. laticeps var. acuminata; M. mahabuleshwarensis var. amazonensis; M. rotata var. rotata; M. siolii). Todas as espécies, exceto M. radiata Hassal var. brasiliensis Grönblad, foram registradas no rio Negro, enquanto no lago Tupé foi registrado, no geral, apenas sete espécies, três de Euastrum e quatro de Micrasterias