ASCOMYCOTA | EUROTIOMYCETES > VERRUCARIALES > Verrucariaceae

Common name:             -

Synonyms:            Verrucaria baldensis

Habitat:                           Urban (for this entry)

Substrata:                      Limestone

Growth form:                 Saxicolous

Thallus:                  Crustose

Perithecia:                      Almost immersed

BLS identity rating: Graded 2/5 (visual identification relatively easy with care)

Crustose thallus more or less immersed, uncracked, smooth with a matt, white to pale blue-grey, somewhat translucent appearance, without blue-green or purple pigment, but often with slightly greenish patches more noticeable in shade; scattered with abundant, small, almost immersed perithecia, around 0.3mm dia., that leave small pits when they decay; the pore-like openings, known as ostioles, are covered by a flat to slightly convex layer of black tissue (involucrellum), and are usually surrounded by some very fine radiating cracks, although only visible under a x20 lens.

Previously regarded as one of the most common and easily recognised Verrucaria lichens on hard limestone, but now being reassessed and separated from the extremely similar Bagliettoa parmigera, which may well be the species represented here. Currently, the only visual distinguishing feature between the two is that Bagliettoa parmigera is said to have a dull, rather than a porcelain-like appearance.

Whereas Verrucaria baldensis was previously treated in the wider sense, here the roles of the two species are being reversed with the above description for Bagliettoa baldensis in the strict sense and Bagliettoa parmigera as sensu lato thereby including previous, sometimes incorrect, records.

And, to confuse matters further, there are also similarities to Bagliettoa calciseda and Verrucaria hochstetteri, although the latter does have much larger perithecia to 0.8mm dia.

The current descriptions confirm that both Bagliettoa baldensis and parmigera are found on limestone, the former where there is slight moisture or seasonal seepage, and the latter simply on sunny surfaces, although it is also tolerant of shade.