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Issue: Vol. 224 No. 2: 28 August 2015
Type: Article
Published: 2015-08-28
DOI: 10.11646/phytotaxa.224.2.1
Page range: 101–139
Abstract views: 34
PDF downloaded: 1

Morphological variability within the Achnanthidium minutissimum species complex (Bacillariophyta): comparison between the type material of Achnanthes minutissima and related taxa, and new freshwater Achnanthidium species from Portugal

Instituto Ciências da Terra (ICT), Pólo da Universidade de Évora, Rua Romão Ramalho n° 59, 7000–671 Évora, Portugal Luxembourg Institute of Science and Technology (LIST), Environmental Research and Innovation Department (ERIN), 41 rue du Brill, L-4422 Belvaux, Luxembourg
Department of Natural Sciences, National Museum of Wales, Cathays Park, Cardiff CF10 3NP, UK
Botanic Garden Meise, Department of Bryophyta & Thallophyta, Nieuwelaan 38, B–1860 Meise, Belgium University of Antwerp, Department of Biology, ECOBE, Universiteitsplein 1, B–2610 Wilrijk, Belgium
Instituto Ciências da Terra (ICT), Pólo da Universidade de Évora, Rua Romão Ramalho n° 59, 7000–671 Évora, Portugal
Luxembourg Institute of Science and Technology (LIST), Environmental Research and Innovation Department (ERIN), 41 rue du Brill, L-4422 Belvaux, Luxembourg
Luxembourg Institute of Science and Technology (LIST), Environmental Research and Innovation Department (ERIN), 41 rue du Brill, L-4422 Belvaux, Luxembourg
Achnanthaceae diversity ecology freshwater nomenclature taxonomy ultrastructure Algae Portugal

Abstract

Two new taxa similar to Achnanthidium minutissimum were common and abundant in samples collected during a survey of benthic diatoms in watercourses from mainland Portugal. They are described here as A. duriense, sp. nov. and A. lusitanicum, sp. nov. In addition, the recently described A. pseudolineare is reported from various localities and its ecology is described in detail. The new Achnanthidium species from Portugal were compared with the type material of morphologically similar taxa: Achnanthidium microcephalum, Achnanthes minutissima, A. minutissima var. cryptocephala, A. minutissima var. inconspicua and A. nana. The analysis of this type material confirmed that Achnanthes minutissima var. cryptocephala should be regarded as a different taxon, and a new combination is proposed, Achnanthidium neocryptocephalum, stat., comb. et nom. nov. Achnanthes minutissima var. inconspicua is now considered as a younger synonym of Achnanthidium lineare. Based on a detailed morphological study of specimens of Achnanthes nana from Scotland, Nepal and Portugal, this taxon is transferred to the genus Achnanthidium as Achnanthidium nanum, comb. nov.