Description & Identification
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|
Belonia russula also has a trentepohlioid photobiont, but the thallus is coarser and cracked, the ascospores are only 3-6 µm wide, and it grows directly on rock in upland overhangs.
Porina ahlesiana has smaller perithecia, 300-500(-700) µm diameter, ascospores 30-50(-70) × 6-9(-15) µm, (6-)7-septate, and grows directly on rock.
Porina atlantica (Ireland; not known from Wales) usually has isidia on the thallus, and the involucrellum covering the perithecium contains numerous large crystals, which are absent in P. effilata.
Thelenella muscorum may also grow on bryophytes on bark and rock, but the thallus is whitish or pale brown, with a green (not orange) photobiont, the perithecia are smaller (300-600 µm diameter) and typically immersed in the substratum, and the ascospores are muriform.
Records from Wales
V.C. 46 (Cardigan). Coedmor National Nature Reserve, SE of Coedmore House, 22/195.432, on bryophytes on vertical rock face sheltered by ivy, 20 March 1996, A. Orange 10998 (NMW - C97.35.657) [originally as P. heterospora].
V.C. 48 (Merioneth). Bryn Bwbach, Ceunant Coch, 23/6295.3642, on slightly calcareous rock face in woodland, 4 May 2002, A. Orange 13840 (NMW - C.2002.017.48) [originally as P. atlantica].
NBN Taxon Key