Observation 166041: Collema subnigrescens Degel.

When: 2014-05-24

Collection location: Serra de São Mamede, Portugal [Click for map]

Who: zaca

No specimen available

According to my reference Collema subnigrescens is quite abundant in my country and is similar to C. nigrescens, which often presents isidia, and to C. ryssoleum, which also lacks isidia; Of the three species is the one with bigger apothecia, in general. Other differences are related with the form and size of the spores:
- C. nigrescens has acicular to baciliform spores, 6 to 11-septate with dimensions: 50-90 x (2.5)3-4.5 um;
- C. ryssoleum has ellipsoidal to fusiform spores, which are wider at center, 5- septate with dimensions:25-45(-50) x (4-)5-8(-10) um;
- C. subnigrescens has acicular spores with one of the ends wider than the other, often curved, 6 to 7-septate with dimensions: (35-)40-75 x (4-)4.5-6.5 um.

I think that the attached photos have sufficient material to lead to the conclusion that this specimen belongs to C. subnigrescens. Concerning the spores I got the following average dimensions: Me = 42 × 5 um ; Qe = 8.4 (N=11), in the ranges: 35.9 – 52.7 x 4.7 – 5.6 um.


Microscopy 1: Sections;
Microscopy 2: Asci and spores.

Proposed Names

87% (1)
Eye3 Eyes3
Used references: P. Carvalho, Collema, Flora Liquenológica Ibérica – Vol. 10, Sociedad Española de Liquenología, 2012.
Based on microscopic features

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Eye3 = Observer’s choice
Eyes3 = Current consensus


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Created: 2014-05-28 07:48:39 CST (+0800)
Last modified: 2014-05-29 23:39:46 CST (+0800)
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