Nostoc flagelliforme has been reported from deserts of all continents and more recently from semiarid environments in southeast Spain and Australia. Its cylindrical thalli are very conspicuous on soils after rains and can be easily differentiated from other taxa and it is considered endangered in some countries, e. g. China. It was firstly described as variety flagelliforme of Nostoc commune but later was considered a separate species. The morphology, fine structure and ecology of populations of both taxa from Australia and different regions of Spain were studied and 16S rRNA and trnL Leu (UAA) genes were sequenced to identify their intraspecific genetic variation. The morphological study revealed the presence of several intermediate morphs, from spheres and sheets to ribbons followed by the cylindrical thalli and the overlapping of cell dimensions, permitting the differentiation of cylindrical morphs from the others. The molecular data did not allow for a distinction between Nostoc commune and Nostoc flagelliforme which is clearly polyphyletic and both show a high genetic diversity. The presence of cylindrical thalli seems to be related to extreme conditions of aridity, usually on soils but occasionally on rock walls. The ecotype that Noctoc flagelliforme represents deserves to be protected for itself and for the evolutionary process it represents opening up the possibility of implementation of recovery measures and even opportunities to explore its biotechnological production from a different point of view.
First record of the alien pest Rhaponticum repens (Compositae) in the Iberian Peninsula.-Rhaponticum repens is reported for the first time for the flora of the Iberian Peninsula. The species is native from Central Asia and has become invasive in Argentina, Canada, Europe and the USA. It was detected for the first time in abandoned fields from Vilablareix, near the city of Girona (Catalonia, Spain) and in the valley of the Vinalopó in Alicante (Valencia, Spain), where it was collected as early as in 1959 but misdentified. Molecular data, based on nrDNA region ITS, suggest that the reported populations may be closely related to plants from the United States. Due to the extremely noxious character of the species and the possible relationship of Spanish plants with the invasive American populations, some kind of monitoring is recommended.
About the presence of Nostoc commune var. flagelliforme (Nostocaceae, Cyanophyceae) on clay soils from arid regions of south east SpainPalabras clave. Cyanophyceae, Nostoc, distribución, ecología, morfología, regiones áridas, SE España.Keywords. Cyanophyceae, Nostoc, distribution, ecology, morphology, arid regions, Southeastern Spain.
Pennisetum clandestinum Hochst. ex Chiov. is a grass native to Central and Eastern Africa, which is reported for the Iberian and European floras from materials collected in the littoral areas of both Alicante and Valencia provinces (eastern Spain). This plant is briefly described, and some ecological and phytosociological data are also reported.
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