Tremella wirthii Diederich, 1996

Westberg, Martin, Timdal, Einar, Asplund, Johan, Bendiksby, Mika, Reidar Haugan,, Jonsson, Fredrik, Larsson, Per, Odelvik, Goeran, Wedin, Mats & Millanes, Ana M., 2015, New records of lichenized and lichenicolous fungi in Scandinavia, MycoKeys 11, pp. 33-61 : 53-54

Tremella wirthii Diederich, 1996

Tremella wirthii Diederich. Bibl. Lichenol. 61: 164. 1996.

Holotype.

GERMANY. Bayern: Neu-Ulm, Holzheim, Obstgarten WSW Steinheim, MTB 7626/2. 6 Feb 1991, V. Wirth 21713 ( STU)

Distribution.

New to the Nordic countries. Tremella wirthii was described by Diederich (1996) based on material from four localities in Germany, growing on an unidentified sterile corticolous lichen. The host was later described as Protoparmelia hypotremella ( Aptroot et al. 1997), a species similar to P. oleagina , from which it differs by its paler colour and its isidia-like granules. Both species are among the few corticolous Protoparmelia species, and grow on old wooden fences and buildings, and on deciduous and coniferous trees ( Aptroot et al. 1997, 2001, 2004, Clerc 2004, Diederich and Sérusiaux 2000, Scholz 2000, Hafellner and Türk 2001, Palice et al. 2006, van den Boom et al. 2007, Kubiak et al. 2010, Kukwa et al. 2012, Himelbrant et al. 2014). Aptroot et al. (1997) reported the presence of Tremella wirthii on specimens of P. hypotremella from Austria and the Netherlands. In the type locality of Protoparmelia hypotremella , in the Netherlands, T. wirthii was found both on P. hypotremella and P. oleagina . The three Scandinavian specimens grow on Protoparmelia oleagina . They were collected on wood of an old hay drying rack in the agricultural landscape of the Siljan Ring, an area with a calcareous bedrock, and the only locality in Sweden were P. hypotremella has been reported. Here, however, Tremella wirthii has not yet been found on that host. In the Nordic countries Protoparmelia oleagina occurs in Norway and Sweden ( Nordin et al 2015). Tremella wirthii forms dark basidiomata, which are rarely bigger than 0.5 mm in diam., on the host thalli (Fig. 15a ). Some micromorphological differences have been found between Swedish and Central European material. The specimens studied in the original description had 2-4 celled, longitudinally septate basidia, and no asexual morph was reported ( Diederich 1996). The three specimens collected in Dalarna show typical basidia with 2 or 4 cells and longitudinal septa (Fig. 15b ), but also basidia with oblique (Fig. 15c ) or transverse (Fig. 15d ) septa are present within the same basidioma. Moreover, in some cases there is an anamorph consisting of catenulate conidia (individual conidia 3-6 × 3-6 µm; Fig. 15e ). Despite these differences, we consider the material from Sweden and Central Europe to be conspecific. The basidium morphology is extremely variable in many species of Tremella ( Zamora et al. 2011, Millanes et al. 2012), and, when present, the occurrence of conidia is not constant in all specimens of the same species. Since the original description was based on four specimens only, the morphological variation within the taxon may well be greater than originally observed. Tremella wirthii is probably overlooked in Sweden, and additional field and herbarium surveys could reveal its presence in places were Protoparmelia oleagina is abundant.

Specimens examined.

SWEDEN. Dalarna: Orsa municipality 61°11.25'N, 14°52.43'E, alt. 255 m. 1 Oct. 2014, Jonsson FU5955 ( S F262967); Dalarna: Orsa municipality 61°11.32'N, 14°52.45'E, alt. 253 m. 1 Oct. 2014, Jonsson FU5956 ( S F262963); Mora municipality 60°55.67'N, 14°37.08'E, alt. 204 m. 2 Oct. 2014, Jonsson FU5957 ( S F262952).

Figures

Figure 15. Tremella wirthii. a Basidiomata on the thallus of Protoparmelia oleagina (S F 262967) b Basidium with one longitudinal septum (S F 262963) c Basidium with one oblique septum (S F 262963) d Basidium with one transeverse septum (S F 262963) e Catenulate conidia (S F 262963). Scale: 0.5 mm (a); 10 mm (b-e).