Lecanora is a genus of lichen commonly called rim lichens.[1]: 279 [2] Lichens in the genus Squamarina are also called rim lichens. Members of the genus have roughly circular fruiting discs (apothecia) with rims that have photosynthetic tissue similar to that of the nonfruiting part of the lichen body (thallus).[1] Other lichens with apothecia having margins made of thallus-like tissue are called lecanorine.[1]
Swiss lichenologist Rosmarie Honegger used electron microscopy in the late 1970s to investigate ascus structure in several major groups of lichen-forming fungi. She defined the Lecanora-type ascus as one characterized by several distinctive features: (1) a non-amyloid, clear ascus wall that is encased in an amyloid outer layer often described as a fuzzy coat; (2) an amyloid dome filled with granular inclusions set within a clear matrix; (3) a clear central layer inside the dome; and (4) a method of opening, or dehiscence, that is rostrate (resembling the shape of a bird's beak – the ascus has a pointed or protruding tip from which the spores are released).[6]
^C.J. Alexopolous, Charles W. Mims, M. Blackwell, Introductory Mycology, 4th ed. (John Wiley and Sons, Hoboken NJ, 2004) ISBN0-471-52229-5
^FLORA OF NEW ZEALAND: Lichens including lichen-forming and licheniculous fungi, Revised second edition, Volume one, D. J. Galloway, Manaaki Whenua Press, Landcare Research 2007, ISBN978-0-478-09376-6