L. aff. incana:  (Galapagos specimens: please refer to the notes below)

Thallus corticolous, saxicolous or terricolous (in the Galapagos only one corticolous specimen is currently known), placodioid leprose, i.e., developing upon a common, shared hypothallus, delimited by a byssoid arachnoid, ‘cottony’ prothallus forming an irregular, not distinctly lobed margin, always lacking a distinct lip, not ‘crisped’(finkii-type sensu Lendemer 2011a); surface deeply grayish green, often with a bluish green tinge, in the herbarium fading to a pale yellowish green; hypothallus moderately to well developed, loose, ‘fluffy’, ‘cottony’, rhizohyphae sparse or absent; granules ecorticate, ill-defined, mealy [(20–)30–70(–100) µm in diam., fairly even in size but ±aggregating in larger clusters (up to 100 µm)], generally loosely packed, typically with some extruding hyphae; photobiont green, coccoid, 7–10 μm in diam.

Spot tests and chemistry: P-, K± sordid yellow, KC-, C-, UV+ bright yellowish white; zeorin and divaricatic acid.

Distribution and ecology: Cosmopolitan, but most reports are from the Northern Hemisphere and the species is rarely reported from the tropics (Flakus & Kukwa 2007; also see the notes below); newly reported here from Galapagos and known only from a single collection, in the agricultural area in the humid zone of Santa Cruz Island, close to the road, on bark of an introduced tree (Syzygium sp.).

Notes: Based on molecular evidence Lendemer (2011b) considers the reported occurrence of L. incana s.str. outside Europe as problematic. He assigns records of L. incana from North America to the newly described L. hodkinsoniana Lendemer (2011b: 1224). Without sequence data it is presently not possible to assess whether records of L. incana from tropical South America (e.g., Flakus & Kukwa 2007, Saag et al. 2009) represent a new species. Both L. hodkinsoniana and the European L. incana s.str. appear to be temperate rather than tropical species and the South American records possibly refer to yet another cryptic, still undescribed species. Without molecular studies it would be premature to describe the South American material as a new. TLC confirms that the Galapagos specimen is chemically identical both with L. incana and L. hodkinsoniana although the thallus superficially closely resembles that of L. finkii – from which the specimen is reliably distinguished only by its chemistry, namely by the negative spot test reactions and bright UV fluorescence.

Nash, T.H., Ryan, B.D., Gries, C., Bungartz, F., (eds.) 2004. Lichen Flora of the Greater Sonoran Desert Region. Vol 2.

Editorial remarks (CNALH: F. Bungartz, 2019): previous North American records of L. incana belong to L. hodkinsoniana; according to:

Lendemer, J.C. 2011. A taxonomic revision of the North American species of Lepraria s.l. that produce divaricatic acid, with notes on the type species of the genus L. incana. Mycologia 103(6): 1216-1229.