A smut fungus on the ovaries of Primula farinosa (bird’s-eye primrose) in GB (also Primula stricta in Europe and China), which produces black powdery spore masses in seed pods. It can be found by squeezing apparently ripe seed pods – infected pods should leave black powder on fingers.
Sori developing in ovaries of the host, as black/brown powdery masses, visible when the seed pods open at their tops. Spores present in spore balls, completely enclosed within a layer (sometimes 2) of sterile cells which often collapse upon drying to resemble an enveloping membrane. Spore balls globose, ovoid to elongate, of 24-46 x 26-64 µm, each composed of (1-)3-15 or more spores. Spores globose, subglobose, ovoid to elongate or irregular, somewhat angular, 8-13.5 x 11-18.5 µm, medium to dark reddish brown. Sterile cells 5.5-13.5 x 6.5 x 20 µm, variable in shape, size, colour and wall thickness, globose, subglobose, ovoid, elongage, pyriform to irregular.
Description derived from Vánky, K. (2012). Smut fungi of the world. St. Paul, Minnesota: APS press.
Not formally assessed. Considered as potentially extinct (EX 1904) in GB & IOM in the current but unofficial Red Data List for Threatened British Fungi (Evans et al., 2006), but a number of recent collections have demonstrated the species is still extant in England. Considered a species of ‘principal importance for the conservation of biological diversity’ in England, and listed in accordance with Section 41 of the Natural Environment and Rural Communities Act 2006. Infrequently recorded, perhaps due to the need for targeted surveying as well as the scarcity and restricted distribution of the host.
The host, Primula farinosa, is Red Listed as Vulnerable in Great Britain due to evidence of decline (VU A2c).
None known on Primula farinosa, but the similar Urocystis primulae can be found on Primula elatior and subspecies; P. fistulosa; P. veris and subspecies; and P. vulgaris. U. primulae possesses much larger spore balls (32-60 x 40-88 µm), with spores 11-16(20) x 12-21 µm.
Urocystis primulae is a specific biotrophic parasite and pathogen of Primula farinosa and possibly P. stricta, infecting host plant ovaries. It is only known from P. farinosa in the UK.
Recent collections are known from VC60 West Lancashire, VC64 Mid-west Yorkshire, VC66 Durham, and VC69 Westmorland. Historical records comprise three single records from VC66, VC64, and VC58 Cheshire.