Dendrocorticium roseolum (Bres. ex Rick) Baltazar & Rajchenb., 2013

Baltazar, Juliano M., Da Silveira, Rosa Mara B. & Rajchenberg, Mario, 2013, Asterostromella roseola Bres. ex Rick is combined in Dendrocorticium (Corticiaceae, Agaricomycetes), Phytotaxa 104 (1), pp. 49-52 : 49-51

Dendrocorticium roseolum (Bres. ex Rick) Baltazar & Rajchenb. , comb. nov. ( Fig. 1 )

MycoBank MB 803436

Ξ Asterostromella roseola Bres. ex Rick, Brotéria Ci. Nat. 7(34): 74, 1938.

Lectotype, designated here: — BRAZIL. Rio Grande do Sul: Santa Maria, 1935, J. Rick, Fungi Rickiani no. 12053 ( PACA!).

Basidiome resupinate, easily detached from substrate, up to 0.5 mm thick. Hymenial surface smooth, fibrillose to cottony under the lens, orange (6B7) to brownish orange (6C8); margin indeterminate, fibrillose, concolorous with the hymenial surface to slightly lighter.

Hyphal system monomitic, generative hyphae simple-septated, thick-walled, 2–5 µm diam., hyphae in the subiculum hyaline, compactly arranged, in the subhymenium yellowish; halocystidia yellowish, thick-walled, straight to sinuous, 4.5–8 µm diam. at the apex, deeply stained in phloxine, with a resinuous, globose cap, 14.5–25.5 µm diam., not projecting above the hymenium; dendrohyphidia abundant, originating in the subhymenium, yellowish, slightly thick-walled, some of them arboriform, 2–5 µm diam. at the base, 0.5–3 µm diam. at the branches; catahymenium present; basidia not found, basidioles cylindrical to clavate, some with a widened base, thin to slightly thick-walled towards the base, up to 100 × 10 µm; basidiospores broadly ovoid to broadly ellipsoid, hyaline, smooth, thin-walled, (13.5–)15–18 × 9–11.5 µm, IKI-, CB-.

Distribution: —Known only from the type locality in southern Brazil.

Additional specimens examined: — Dendrocorticium ancystrophylli : GABON. 14 km N from Libreville , 5 March 1978 ( LY 8603 , LY 8609 ) .

The name ‘ Asterostromella roseola Bres. ’ has been reported two times in literature, both by Rick (1938, 1959). However, Bresadola had described only two Asterostromella Höhn. & Litsch. species : A. brasiliensis Bres. , based on a Rick’s collection, and A. torrendii Bres. , based on a C. Torrend’s collection ( Bresadola 1926). According to Bresadola’s descriptions, basidiospores of both species are smaller than those in A. roseola and they do not seem to be conspecific. Type specimens of A. brasiliensis and A. torrendii could not be traced by us.

Probably Rick did not intend to propose a new species when he referred to A. roseola since he did not use the annotation ‘nov. spec.’, or any other variation, as he used to do in his works. It is possible that he was using a name given by Bresadola in a letter, and assumed that Bresadola would formally propose the name in one of his publications, which never happened. However, considering that this is a good morphological species and that the taxonomic treatment in Rick (1938) fulfills the requirements for a valid and effective publication, we consider Rick (1938) the original publication for A. roseola . We select a lectotype since Rick (1938) has not cited any specimen when treated the species.

Due to the combination of its microscopic features, A. roseola does not fit exactly in any of the currently accepted genera of corticioid fungi. The combination of a monomitic hyphal system, the presence of dendrohyphidia forming a catahymenium, the ellipsoid to broadly ellipsoid, large, smooth, thin-walled, and IKI- basidiospores, and the fibrillose to cottony consistency of the basidiome, supports its inclusion in Dendrocorticium M.J. Larsen & Gilb. However , all species in the genus so far known differ by having clamped generative hyphae. Dendrocorticium ancistrophylli Boidin & Gilles (1998) is the only species in the genus that has yellowish, slightly thick-walled dendrohyphidia similar to those of A. roseola —all other species have hyaline and thin-walled dendrohyphidia.

Yellowish to slightly brownish and somewhat thick-walled dendrohyphidia are known in species of Cytidia Quél. and Punctularia Pat. Nevertheless , in Cytidia basidiomes are cupuliform, subgelatinosus when fresh and coriaceous when dry, and in Punctularia they are gelatinous and the hymenophore is tuberculate or with radial ridges ( Bernicchia & Gorjón 2010). Corticium Pers. species have hyaline dendrohyphidia and thick-walled basidia at the basal part, while in A. roseola only some basidioles are slightly thick-walled. Mature basidia were not found in the lectotype.

The combination of dendrohyphidia and simple-septate generative hyphae is somewhat unusual in species of corticioid fungi. Some species of Dentrothele Höhn. & Litsch. show this combination of characters ( Gorjón & Bernicchia 2010, Nakasone & Burdsall 2011). However, contrary to A. roseola , species in Dendrothele have abundant crystals in the context and grow on bark of living trees. Though we do not have precise data on A. roseola substrate, the exsiccata points that the specimen was growing on dead wood. Dentocorticium pilatii (Parmasto) Duhem & H. Michel and Marchandiopsis quercina (J. Erikss. & Ryvarden) Ghob. -Nejh. also present a combination of dendrohyphidia and simple-septate hyphae ( Duhem & Michel 2009, Ghobad-Nejhad et al. 2010). However, D. pilatii has basal hyphae with skeleto-binding ramifications and basidiospores are smaller than those of A. roseola . Marchandiopsis quercina has gelatinous basidiomes and bisporic basidia— this last feature could not be checked in A. roseola .

Morphologically, the closest species to A. roseola is Dendrocorticium ancistrophylli . They share the presence of yellowish, slightly thick-walled dendrohyphidia, halocystidia and ovoid to ellipsoid basidiospores. Dendrocorticium ancistrophylli was described from Gabon and differs by smaller cystidia and basidiospores, and by clamped generative hyphae.

Figures

FIGURE 1. Microscopic structures of Asterostromella roseola (lectotype, Fungi Rickiani no. 12053, PACA). A. Basidiospores. B. Halocystidia. C. Dendrohyphidia. D. Generative hyphae.