Atrozythia J.K. Mitch., Quijada, Garrido-Ben. & Pfister, in Mitchell, Garrido-Benavent, Quijada & Pfister, IMA Fungus 12(no. 6): 16 (2021)

Index Fungorum number: IF 838699; MycoBank number: MB 838699; Facesoffungi number: FoF 15027;

Etymology – from the Latin for black (ater) and the genus name “Zythia,” referring to the macroscopic re- semblance to Zythia species, but with a dark coloration.

Sexual morph: Apothecia of Atrozythia differ from Zythia in their colour (black vs. orange) and from Sarea because of their white to light blue grey pruina. Paraphyses in Atrozythia are unbranched, whereas those in Sarea are always branched or anastomose, at least in the basal cells. Zythia can have unbranched paraphyses but differs from Atrozythia in the amount and colour of lipid guttules, orange and abundant vs. yellowish and sparse, respectively. Atrozythia has a hyaline ectal and medullary excipulum that are sharply delimited by a narrow dark brown pigmented layer; in Zythia there is no brown pigmented layer between these layers. In Sarea, the medullary excipulum is always differentiated by its dark brown colour. Asexual morph: see Sigler & Carmichael, Myco- taxon 18: 502-505 (1983).

Type speciesAtrozythia klamathica J.K. Mitch. & Quijada

Notes – This genus currently encompasses two species, both apparently uncommon or under-collected, with one known only in an apothecial morph and the other only in a hyphomycetous asexual morph. Both are found on dead or living conifers; there are some indications of a resinicolous habit in the type species, A. klamathica, but additional information is needed to elucidate the ecology of these fungi. In our phylogenetic analyses, the affinities of this group apparently lie closer to Zythia than to Sarea, but Atrozythia species are located on a relatively long branch compared to these two genera. There are apparently no closely matching, unnamed environmental sequences on GenBank assignable to this genus, possibly suggesting rarity rather than merely being overlooked.