Porina rivalis

Porina rivalis
Scientific classification
Domain:	Eukaryota
Kingdom:	Fungi
Division:	Ascomycota
Class:	Lecanoromycetes
Order:	Gyalectales
Family:	Trichotheliaceae
Genus:	Porina
Species:	P. rivalis
Binomial name
Porina rivalis Orange (2015)

Porina rivalis is a species of semi-aquatic, saxicolous (rock-dwelling), and crustose lichen in the family Trichotheliaceae. Found in Great Britain, it was formally described as a new species in 2015 by lichenologist Alan Orange. The type specimen was collected in Nant Walch near Llanwrtyd Wells (Breconshire) at an altitude of 230 m (750 ft); here the lichen was found growing on stones submerged in a shaded stream. The species had been known previously from streams in Wales, but it had been incorrectly identified as Porina lectissima. Porina rivalis has also been recorded from streams in South-west England and North England. It has a thin brown thallus (20–70 μm thick) with prominent dark brown or black perithecia. Its ascospores are shaped like narrow ellipsoids, have three septa, and typically measure 13.0–17.5 by 4.0–5.5 μm.