Menegazzia is a genus of lichenized fungi containing roughly 70 accepted species.[1] The group is sometimes referred to as the tree flutes, honeycombed lichens, or hole-punch lichens. The most obvious morphological feature of the genus is the distinctive perforations spread across the upper side of the thallus. This makes the group easy to recognise, even for those not particularly familiar with lichen identification.
The genus has a sub-cosmopolitan distribution (excluding Antarctica), but is concentrated in Australasia, Melanesia, and southern South America. Most species grow exclusively on trees, but some grow on rocks, moss, and/or soil.[1]
Menegazzia was described by the Veronese lichenologist Abramo Massalongo in 1854.[2] He named it after his friend Luigi Menegazzi (1795-1854), who was a naturalist.[3]
Placement of Menegazzia within the Parmeliaceae has now been confirmed by several molecular studies.[4][5][6] However, the exact position of the genus within the Parmeliaceae remains uncertain. It is unplaced within the Parmeliaceae. Previously, the morphologically similar genus Hypogymnia was thought to be the sister genus to Menegazzia, with some authors even separating these two genera into a family of their own, the Hypogymniaceae.[7] However, no molecular phylogenies to date have supported this grouping.[4][5][6]
There are three accepted subgenera within Menegazzia: Dispora, Octospora, and Megamenegazzia.[8] However, the monophyletic nature of these three groups remains unknown.
The thallus of Menegazzia is its most distinctive feature. It is foliose, dorsiventral, lobate, and often rosette-forming, though many species can also be irregularly spreading. It is heteromerous, that is, it contains an upper cortex, medulla, green algal layer (occupied by Trebouxia spp.), and lower cortex. The thallus can be loosely or closely attached to the substrate, depending on the species. Lobes are generally hollow and inflated, with perforations throughout the corticate upper surface. Only two species of Menegazzia are known which do not contain perforations (M. eperforata, and an as yet undescribed taxon from Papua New Guinea). Many species can be sorediate, but only a few isidiate. Maculae are often present, especially at the lobe tips. The lower surface is also corticate, naked, and often uniformly attached to the substrate (except in M. inflata). This surface is always blackened, and without rhizines. Internal cavities have walls which are most often white, but in some species they can be pigmented or blackened.[9]