Cyphellostereum ushimanum
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| Cyphellostereum ushimanum | |
|---|---|
 | |
| Resupinate fruiting bodies (white arrows) and fibrous thallus | |
Scientific classification  | |
| Kingdom: | Fungi |
| Division: | Basidiomycota |
| Class: | Agaricomycetes |
| Order: | Agaricales |
| Family: | Hygrophoraceae |
| Genus: | Cyphellostereum |
| Species: | C. ushimanum |
| Binomial name | |
| Cyphellostereum ushimanum H.Masumoto & Y.Degawa (2022) | |
Cyphellostereum ushimanum is a species of lichen-forming fungus in the family Hygrophoraceae.[1] This basidiolichen was discovered and described in 2022 from a single location on Amami Ōshima island in Japan, where it grows on the bark of Japanese cedar trees. The species has microscopic feeding structures (haustoria) that penetrate its cyanobacterial partner, a feature that required an update to its genus, Cyphellostereum. The lichen produces small, white, paper-thin reproductive structures adjacent to its bluish-green thallus.
The species was formally introduced and described as Cyphellostereum ushima by Hiroshi Masumoto and Yousuke Degawa, who based the epithet on an indigenous pronunciation of the island name "Ōshima". Their morphological study, combined with internal transcribed spacer rDNA data, placed the fungus in a strongly supported clade within the genus Cyphellostereum, sister to C. unoquinoum and C. phyllogenum. Together these taxa share the absence of clamp connections and an incomplete hyphal sheath around the cyanobacterial trichomes, yet C. ushima alone have intracellular tubular haustoria.[2]
The discovery required a slight revision of the generic concept. Classical Cyphellostereum species were thought to lack haustoria and to form stipitate, cup‑like fruiting bodies, whereas the new species demonstrates that resupinate basidiomata and haustorial penetration of the photobiont both fall within the phylogenetic limits of the genus. As a consequence, the authors emended the diagnosis of Cyphellostereum to encompass a broader range of thallus architectures and hymenophore morphologies. [2]