Diplotomma alboatrum Caliciaceae
Diplotomma alboatrum

Growth type crustose. Chemical results negative
On calcareous rocks and mortar, also recorded from nutrient-enriched, basic-barked trees.

Very variable. White, pale or dark grey thallus, apothecia often pruinose with thin grey margins. Spores brown, 1-3 septate becoming submuriform, (11-)15-20(-30) x (6-)8-10(-17) Ám. Microscope photographs below.
Sometimes host to Arthonia punctella and Verrucaria latericola

Similar: D. chlorophaeum. K+ yellow>red, P+ orange. Discs not pruinose.
Diplotomma hedinii, spores without longitudinal septa, frequently curved.
D. pharcidium. Corticolous, often not pruinose, spores +/- slightly curved.
Diplotomma murorum occurs on the thallus of Caloplaca teicholyta.


Diplotomma alboatrum

Diplotomma alboatrum

Diplotomma alboatrum

Microscope photographs
Diplotomma alboatrum, spores
Diplotomma alboatrum
Dorset. September 2012, February 2013, March 2014

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