Arthonia almquistii Vain.

Meddeland. Soc. Fauna Fl. Fenn., 10: 209, 1883.
Distribution: C - Tosc (Brackel 2015, 2016).
Description: Thallus inapparent, not lichenized, lichenicolous on different species of saxicolous lichens, mainly Porpidiaceae and Agyriaceae. Apothecia arthonioid, rounded, convex, immarginate, 0.1-0.25(-0.6) mm across, black, immersed to erumpent, crowded and partly confluent, with a rough surface. Proper exciple poorly developed, dark brown, 8-10 μm wide; epithecium dark brown, 10-15 μm thick; hymenium colourless to pale brown, (30-)40-45 μm high; paraphysoids short-celled, strongly branched and anastomosing, 2-2.5 μm thick, the apical cells dark brown-pigmented, 3-4.5(-5.5) μm wide; hypothecium 40-70 μm high, I+ red, with a colourless to pale brown subhymenial layer and a brown to dark brown basal zone. Asci 8-spored, broadly clavate, semi-fissitunicate, with a large apical dome, a distinct ocular chamber, and a K/I+ bluish ring-structure, Arthonia-type. Ascospores 1-septate, hyaline, clavate, 10.5-15(-18) x (3-)4.5-5(-6) μm, with a gelatinous perispore reacting I+ red. Photobiont: absent. Spot tests: thallus K-, C-, KC-, P-. Chemistry: without lichen substances.
Note: a widespread but not common lichenicolous fungus growing on different saxicolous crustose lichens (mainly Porpidiaceae and Agyriaceae); the sample from Tuscany was on Trapelia coarctata.
Growth form: Lichenicolous fungus
Substrata: rocks, soil, terricolous mosses, and plant debris
Reproductive strategy: mainly sexual
paras crustose lichens

Commonnes-rarity: (info)

Alpine belt: absent
Subalpine belt: absent
Oromediterranean belt: absent
Montane belt: absent
Submediterranean belt: absent
Padanian area: absent
Humid submediterranean belt: extremely rare
Humid mediterranean belt: extremely rare
Dry mediterranean belt: absent

pH of the substrata:


Solar irradiation:








Altitudinal distribution:


Predictive model
Herbarium samples