• Verrucaria knowlesiae P.M.McCarthy
Verrucaria knowlesiae
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This endemic, shaded-limestone-loving Verrucaria is virtually invisible from above so close inspection of the substrate is required to locate it. The brown-grey, cracked vaguely superficial thallus has discs (perithecia = 0.12-0.3mm diam.) fully visible to semi-immersed but not covered by a layer of thallus. The discs are, however, covered by a shield of tissue the involucrellum. The average spore size is in the range 9 x 6ųm. In Ireland the species is known only from the Aran Islands.

Key characteristics

  • Thallus semi-immersed and easily missed or superficial brownish-grey
  • Discs with an involucrellum but no thalline covering; distinguished from V. bulgarica by the larger perithecia.

Original text submitted by Vince J. Giavarini

 Simms, M. J., (2016). Verrucaria knowlesiae P.M.McCarthy. [In] LichenIreland. Accessed on 2018-08-18.