Porina effilata

This rare pyrenocarpous lichen overgrows bryophytes on base-rich bark and rock in mild oceanic parts of the British Isles. The thallus is pale orange or pinkish when fresh (containing Trentepohlia), turning pale grey or grey-green in the herbarium, and forming a thin smooth layer over bryophytes. There are no isidia. The perithecia are large, mostly 400-900 µm diameter, coloured like the thallus or pale pink-brown or pale yellow-brown, never with dark pigments. The perithecia are usually easily seen, forming hemispherical projections, but can sometimes be immersed in the thallus. In section the perithecium has only yellow pigment; the ascospores are long and 

narrow, 40-90 × 8-12 µm, and transversely 7-14-septate.

 

The occurrence of this species in Wales is likely to be limited by two factors, among others: the need for base-rich rock or bark, and a presumed requirement for mild, oceanic conditions. Even at the two known Welsh sites, suitable calcareous rock is scarce. Thus the Welsh population is always likely to be small, although the species 

could still be found on sufficiently base-rich bark.

 

The species has been confused with several others, and most records originally appeared under other names.

 

	Photos: Alan Orange