Caeruleum (lichen)

Caeruleum is a genus of lichen-forming fungi in the family Acarosporaceae. Two species are currently recognized, C. heppii and C. immersum. Caeruleum is generally similar to the related genus Acarospora.

Naming
The generic name, "Caeruleum", refers to the blue color stain of the after treatment with Lugol's iodine.

Taxonomy
The genus Caeruleum was described in 2012 by Linda in Arcadia and Kerry Knudsen, with the type species Caeruleum heppii ("Hepp's cracked lichen"). C. heppii had previously been described as a species of both Acarospora and Myriospora. An additional combination was also erected as Caeruleum immersum. C. immersum has also been assigned as a species of Acarospora and Myriospora in the past. Arcadia & Knudsen (2012) noted that future research may indicate that C. immersum represents a synonym of C. heppii.

Caeruleum is one of eleven genera within the Acarosporaceae family of fungi.