Helotiales » Dermateaceae

Arctomollisia

Arctomollisia Raitv. , IF:542207

Apothecia superficial, broadly sessile, scattered. Disc 0.3–2 mm, surrounded by a distinct margin, greyish to pale ochraceous. Receptacle cup-shaped, with incurved margins when dry, externally blackish, smooth with downy margin. Ectal excipulum of textura globulosa, cells medium to dark brown, 6–9 μm in diameter, covered with abundant grana of small groups of blackish-brown opaque cells. Margin composed of a dense palisade of cylindric or cylindric-clavate, aseptate or septate outgrowths. Asci arising from croziers, cylindric-clavate to clavate, 8-spored, apical pore blue in LUG or MLZ. Spores clavate, often slightly inequilateral, hyaline, aseptate. Paraphyses lanceolate, hyaline, without contents, exceeding the asci.
Type : Arctomollisia oxyparaphysata (Rehm) Raitv.
Taxonomic notes. A peculiar dermateaceous fungus having ectal excipulum very similar to Pyrenopeziza spp., lanceolate paraphyses and a dense palisade of long, hair-like cells was present among collections by L. N. Vassiljeva. It would be unnatural to place it in Mollisiopsis Rehm because the type and other species have mollisioid excipulum without prominent grana covering the outer layer of the excipulum. Looking for similar species I discovered that Mollisia oxyparaphysata Rehm is very similar to the fungus from the Magadan area but differs from it in smaller asci and spores and differently shaped marginal hair-like cells. Dennis (1962) has combined M. oxyparaphysata into Cenangiopsis Rehm but this cannot be accepted because the type species of Cenangiopsis, C. quercicola (Romell) Rehm (Type in S studied), is clearly an encoelioid fungus belonging to the Helotiaceae whereas Mollisia oxyparaphysata (type specimen in S studied) is clearly a Dermateaceous species having ectal excipulum similar to Pyrenopeziza. The best solution seems to be erecting a new genus for these two species which do not fit Pyrenopeziza because of the lanceolate paraphyses.

Reference:

Raitviir, A. 2008. The Helotiales of the Magadan and Chukotka areas of the Russian Arctic. – Sommerfeltia 31: 179-190.

 

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