Caloplaca arnoldii Teloschistaceae
Calogaya oblitterata (Caloplaca arnoldii)

Growth type crustose
Chemical results: K+ crimson

Usually coastal on well-illuminated siliceous rocks.

Forms neat patches or rosettes of orange-yellow to deep orange thallus, the marginal lobes shorter and slightly fan-shaped. Apothecia scarce, flat orange discs with a thin margin. Asci 8-spored, spores polarilocular, 8-14 x 4-7 Ám with a wide septum (about or more than 1/3 of spore length).

Similar: Caloplaca saxicola occurs on calcareous rocks

Caloplaca arnoldii

Caloplaca arnoldii
Caloplaca arnoldii
On chert, Portland, Dorset. February 2016

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