Collection location: Parque de Monsanto, Lisboa, Portugal [Click for map]
I returned to the site of my first sighting of this species in order to obtain a sample for analysis.
Collema ryssoleum is a species with a wide distribution but is not common here. It is very similar to other species of Collema with pustules and folds, making it difficult to separate from those, especially Collema subnigrescens, which also lacks isidia. The main difference is the size of the spores: 25-45 × 5-8 um in C. ryssoleum vs 40-75 x 4.5-6.5 um in C. subnigrescens, with similar shapes.
I obtained the following dimensions for the spores:
(30.4) 33.4 – 43.7 (44) x (4.3) 4.33 – 5.2 (5.9) µm
Q = (6.3) 6.5 – 9.2 (9.8) ; N = 11
Me = 38.3 × 4.9 µm ; Qe = 7.9.
Its habitat rock, basaltic this case, but can occur at sites on siliceous rocks, typically seepage.
|I’d Call It That||3.0||6.55||1||(zaca)|
sum(score * weight) /
(total weight + 1)