Angustisporum Exobasidium is a mushroom art family of Nacktbasidienverwandten (Exobasidiaceae) from the order Ustilaginomycotina . It is an endoparasite of the alpine bearberry ( Arctostaphylos alpinus ). Symptoms of the infection by the fungus are discolored leaf tops and enlarged leaves of the host plants. The species is distributed holarctic .
Exobasidium angustisporum is initially invisible to the naked eye. Symptoms of the infestation are a yellowish-white to dark purple discoloration of the upper surface of the leaves, enlarged leaves and, in the late stage, protruding mycelium on the underside of the leaf .
The mycelium of Exobasidium angustisporum grows as with all exobasidium intercellular and forms Saugfäden that grow into the storage tissue of the host. The three- to five-pore basidia are unseptate. They grow directly from the host epidermis or from stomata . The cylindrical to banana-like shaped spores are hyaline and 11–16 × 2–3.5 µm in size. At first they are unicellular, later they have up to a septum . The conidia are 5–10 × 1–2 µm in size and bacillus.
The known distribution area of Exobasidum angustisporum includes a Holarctic area with Europe and North America .
The host plant of Exobasidium angustisporum is the alpine bearberry ( Arctostaphylos alpinus ). The fungus feeds on the nutrients present in the storage tissue of the plants, its basidia later break through the leaf surface and release spores. The spores germinate into conidia, from which new mycelium then develops. The species occurs from planar to montane layers.
- John Frithiof Nannfeldt: Exobasidium, a taxonomic reassessment applied to the European species . In: Symbolae Botanicae Upsalienses . tape 23 (2) , 1981, pp. 1-71 .