Images of British Lichens
Opegrapha physciaria (Nyl.) D.Hawksw. & Coppins
Thallus parasitic, non-lichenised, immersed in the host tissue; apothecia black, lirellate, irregularly rounded or elongate, gall-like, produced on the surface of the host, ascospores 3-septate, 12-17 × 4-6 µm (dimensions from Pentecost & James, in Smith et al., 2009). Host-specific on Xanthoria parietina, apparently rare, coastal, seemingly not following the recent expansion of the host with enhanced atmospheric nitrate/ammonia deposition.
Refs: Smith et al. (2009), 642; Wirth, Hauck & Schulz (2013), 2: 787 (as Phacothecium varium).
The specific name originates from when, long ago, Xanthoria parietina was included in the genus Physcia.
|On thallus of Xanthoria parietina on Ash (Fraxinus excelsior) in coastal woodland, Slapton, Devon, August 2011|
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uploaded February 2014