361 Nova Hedwigia Vol. 91 issue 3–4, 361–376 Stuttgart, November 2010 Article © 2010 J. Cramer in Gebr. Borntraeger Verlagsbuchhandlung, Stuttgart, Germany www.borntraeger-cramer.de DOI: 10.1127/0029-5035/2010/0091-0361 0029-5035/2010/0091-0361 $ 4.00 The rediscovery of Dicranella circinata (Dicranellaceae, Bryophyta), with comments on other southern South American species of Dicranella Juan Larraín 1 , Guillermo Suárez 2 , Halina Bednarek-Ochyra 3 and Ryszard Ochyra 3 1 Departamento de Botánica, Universidad de Concepción, Casilla 160-C, Concepción, Chile; e-mail: juanlarrain@udec.cl 2 Fundación Miguel Lillo, Miguel Lillo 251, San Miguel de Tucumán (4000), Tucumán, Argentina; e-mail: suarezgm@csnat.unt.edu.ar 3 Institute of Botany, Laboratory of Bryology, Polish Academy of Sciences, ul. Lubicz 46, 31-512 Kraków, Poland; e-mail: h.bednarek@botany.pl; r.ochyra@botany.pl With 6 figures Larraín, L., G. Suárez, H. Bednarek-Ochyra & R. Ochyra (2010): The rediscovery of Dicranella circinata (Dicranellaceae, Bryophyta), with comments on other southern South American species of Dicranella. Nova Hedwigia 91: 361–376. Abstract: Fertile populations of Dicranella circinata Herzog, a poorly known endemic moss species from southern Chile, were recently found in Chiloé Island. The species was previously known only from the type collection, which consists of just a few sterile plants. The first illustrations of this previously insufficiently known taxon, and the description of its sporophytes, together with new geographical, ecological and morphological data, are here provided. Discussion about the taxonomy and nomenclature of the other southern South American species of Dicranella is also presented. We propose two new combinations for names previously placed in the neglected genus Anisothecium Mitt. [Dicranella elegans (Duby) Larraín, and Dicranella fontana (Herzog) Larraín], and new synonyms for D. aulacocarpa Mont. and for D. pseudorufescens Cardot & Broth. Key words: Chile, Chiloé Island, Dicranella circinata, Dicranellaceae, taxonomy. Introduction The genus Dicranella (Müll.Hal.) Schimp. is a group of small to medium-sized terricolous dicranoid mosses characterized by the erect to erect-spreading, straight to sometimes secund or even circinate leaves, sometimes with a flexuose subula, without differentiated alar cells, and a relatively narrow costa (with some exceptions), occupying less than 1/4 of the leaf base. The leaves usually clasp the stem thus