The genus Achnanthidium Kutz. (Achnanthales, Bacillariophyceae) in Bolivian streams: a report of taxa found in recent investigations
Morales, Eduardo A.; Ector, Luc; Fernández, Erika; Novais, Maria Helena; Hlúbiková, Daša; Hamilton, Paul B.; Blanco, Saúl; Vis, Morgan L.; Kociolek, J. Patrick
Populations of Achnanthidium Kütz. occurring in samples collected from epilithic habitats in Bolivian rivers and streams were studied using light (LM) and scanning electron microscopy (SEM). Thirteen taxa were identified, 8 of which corresponded to diatoms that could not be identified based on local, regional or global literature. The known taxa include Achnanthidium exiguum (Grunow) Czarn., Achnanthidium jackii Rabenh., Achnanthidium minutissimum (Kütz.) Czarn., Achnanthidium saprophilum (H. Kobayasi et Mayama) round et Bukht., and Achnanthidium sehuencoense E. Morales. Of these, only A. minutissimum, A. jackii, and A. sehuencoense were found in relative abundances between 1 and 60 %. The undetermined taxa include Achnanthidium cf. alpestre (lowe et Kociolek) Lowe et Kociolek, Achnanthidium cf. catenatum (J. Bílý et Marvan) Lange-Bert., Achnanthidium cf. modestiforme (Lange-Bert.) Van de Vijver, Achnanthidium cf. rivulare Potapova et Ponader, Achnanthidium sp. 1 COROICO, Achnanthidium sp. 2 COROICO, Achnanthidium sp. 2 ROCHA, Achnanthidium sp. 2 SEHUENCAS, all of which occurred at relative abundances less than 1 %. However, one undetermined taxon, namely Achnanthidium sp. 2 SEHUENCAS, was found under SEM in sufficient numbers to justify its description as a new species: Achnanthidium cadimae E. Morales, E. Fernán dez et Ector. Additionally, type material of Achnanthes kryophiloides Hohn, originally described from the Peruvian Amazon, was examined using LM and SEM, thereby establishing its distinctness from A. sehuencoense, which thrives in Bolivian streams. Since Hohn's taxon is a later homonym of a species described from Spitsbergen, Norway, a new name is required for the Peruvian taxon: Achnanthidium peruvianum E. Morales et Ector nom. nov. Based on current taxonomic and ecological literature for the genus, the above taxa are discussed.