Bacidia stenoloma (Müll. Arg.) Zahlbr.

Flakus, Pamela Rodriguez & Printzen, Christian, 2014, Molecular evidence for the occurrence of the lichen genus Biatora (Lecanorales, Ascomycota) in the Southern Hemisphere, Phytotaxa 172 (3), pp. 271-279 : 276-277

Bacidia stenoloma (Müll. Arg.) Zahlbr.

Basionym: Patellaria stenoloma Müll. Arg. (1888: 67)

PARAGUAY. [Cordillera], Cordillera de Períbebuy, B. Balansa 4159 (G-00290715!— lectotype, designated here; G!—isolectotypes) .

Biogeographical Considerations

So far, the distributional range of Biatora was thought to be restricted to the Holarctic Region , where it occurs from the Arctic through suboceanic and montane coniferous forests to the laurisilva of Madeira. Most of the species display a preference for old growth coniferous forests ( Printzen & Palice 1999; Printzen & Tønsberg 1999). The genus is now also known from four localities in southern Argentina and Chile, in old humid Patagonian forest and near recently burned forest, where the single species found so far seems to be rare on trunks of Nothofagus spp. at elevations between sea level and 874 m.

Earlier, historical records of “ Biatora ” species from the Southern Hemisphere date back to the time when the circumscription of Biatora was not yet clear ( Printzen 1995) and include such species as B. cinnabarina (Sommerf.) Fr. , B. icterica Mont. , B. corallina (Eschw.) Hook. & Taylor , B. furfurosa (Tuck.) Tuck. , B. glaucopa (Hook. & Taylor) Räsänen , B. glaucopa var. oculans (Nyl) Räsänen , B. pulverea (Borrer) Hook. & Taylor , B. pyrrhomelaena Tuck. , and B. byssacea Hampe , which nowadays belong to different lichen genera like Ramboldia , Schaereria , Malmidea , Phyllopsora , Megalaria , Micarea and Palicella ( Müller Argoviensis 1894; Gyelnik 1937; Swinscow & Krog 1981; Kalb et al. 2008; Kalb et al. 2011; Czarnota et al. 2010; Rodriguez Flakus & Printzen 2014).

We studied the type material of Bacidia rufinula (Müll. Arg.) Zahlbr. , B. pallida Darb. and B. stenoloma (Müll. Arg.) Zahlbr. described from South America ( Zahlbruckner 1926; Galloway & Quilhot 1998; Calvelo & Libertone 2002; Filson 1996). These species do not correspond to the modern circumscription of Biatora because the hyphae inside the exciple of B. rufinula and B. pallida have rounded cells (paraplectenchymatous) with wide lumina and a less gelatinized matrix. Bacidia stenoloma differs from typical Biatora by the distinct apothecial margin reminiscent of the exciple of Fellhanera . One collection in G annotated as a syntype differs from B. stenoloma by 7-septate ascospores and corresponds well with Biatora . It might be necessary to describe it in this genus eventually. However, we would postpone such a step until fresh material becomes available to generate DNA sequence data. The final position of all those species requires more study. For the time being they should be classified within Bacidia s. lat. Biatora macloviana Flot. should be considered a “nomen nudum”. It was mentioned in an exsiccate of F. Flotow (Flotow undated) but was never formally described ( Grassi 1950; Swinscow & Krog 1981; Galloway & Quilhot 1998; Calvelo & Liberatore 2002). Biatora tucumanensis Räs. has black apothecia with a brown-black hypothecium and can therefore not be a Biatora . Biatora subduplex (Nyl.) Printzen has been reported from Antarctica by Øvstedal & Lewis Smith (2001). We have not seen the collection, on which this report is based, but since it is said to have black apothecia without margin, a yellow-brown hymenium and strongly branched paraphyses, it cannot be this species and is likely to belong to Micarea instead.

Likewise, “ Biatora ” species reported from Oceania, such as the saxicolous B. orosteoides Räs. with black disk and immarginate apothecia ( Räsänen 1944; Elix & McCarthy 1998) is not a Biatora in its current circumscription. The type specimen for B. albipraetextata (Knight) Hellb. reported from Chile and New Zeland has not been found in WELT. However its ovoid ascospores with 10 µm width also indicate that it does not belong to Biatora , all species of which have narrowly ellipsoid to bacilliform ascospores ( Galloway & Quilhot 1998; Galloway 2007). Hence, the discovery of B. rufidula s. lat. in Patagonian forests of Chile and Argentina represents the first reliable report of this genus from the Southern Hemisphere.

At present, we can only speculate about the origin of the bipolar distribution in the Biatora rufidula group. In the Northern Hemisphere, B. aegrefaciens and B. rufidula show a more and less circumboreal distribution ( Printzen 1995, Printzen & Tønsberg 1999; Printzen et al. 2002), although B. aegrefaciens has only been collected very rarely. A collection of B. rufidula from Larix decidua on Iceland ( Printzen 1995) may indicate a relatively recent dispersal of the species. Larix is not naturally occurring on Iceland and a typical forest species is rather unlikely to have survived the last glaciation there. Several other species with a bipolar distribution have recently been investigated, e. g. Flavocetraria cucullata (Bellardi) Kärnefelt & Thell , F. nivalis ( L.) Kärnefelt & Thell ( Bjerke & Elvebakk 2004), Usnea sphacelata R. Br. ( Wirtz et al. 2004) , U. lambii (Imshaug) Wirtz & Lumbsch ( Wirtz et al. 2008) , and Cetraria aculeata (Schreb.) Fr. , ( Fernández-Mendoza & Printzen 2013). The dispersal of C. aculeata to the Southern Hemisphere has been dated to the late Pleistocene by Fernández-Mendoza and Printzen (2013). Because C. aculeata is a terricolous species of open habitats, it is unclear whether a similar age can be assumed for the disjunction of a species group that is restricted to forest stands. If the basal position of the South American samples in the phylogenetic tree ( Fig. 1 ) were supported by further data, this would indicate a higher age of the disjunction, which then would seem to predate the diversification of the group in the Northern Hemisphere. Before any firm conclusions can be drawn it is, however, necessary to clarify the species status of B. aegrefaciens , B. nobilis and B. rufidula in the north, based on a population-level sampling and more gene loci.

Figures

FIGURE 1. Bayesian consensus phylogram obtained from 16 OTUs and ITS gene loci of the Ramalinaceae clade. Cliostomum griffithii was used as outgroup. Support values (in bold) are given as “BP/PP”. Biatora from South America is placed within the rufidula clade with a ML bootstrap value of 99% and a posterior probability of 1.0.