Observation 188277: Arthonia elegans (Ach.) Almq.
When: 2014-11-02
Who: zaca
No herbarium specimen

Notes: In the British Flora (and by extension I believe the same happens here) only two species of Arthonia are cited to have apothecial sections K+ purple, violet or magenta: A. cinnabarina and A. elegans. Taken into account my previous observations and the features of these speciens, I thought that it belong to the first of that species. Moreover, despite the similarity referred for the two species, the apothecia of the first is usually (white) pruinose specially at the margin of apothecia, where the pruina is cinnabar-red, while the second is usually not pruinose or with pruina along the edges. This specimen is pruinose, having both white pruina and red pruina (mainly at margin) on apothecia. The spores of the two species are similar in shape but very different in dimensions and septation:
A. cinnabarina: (18) 20-28 × 7-9.5 um; (2) 4 to 5 (6) septa;
A. elegans: (12) 14 – 19 × 4.5-7 um; (2) 3 or 4 (5) septa.
For my specimen I obtained:
(13.4) 13.8 – 15.9 (16.3) x (4.8) 4.9 – 5.7 (6) µm; Q = (2.3) 2.5 – 3 (3.1) ; N = 25; Me = 14.9 × 5.3 µm ; Qe = 2.8; Most spores with 3 septa.
Therefore, I believe this can be classified as A. elegans, despite of having pruinose apothecia.

Images

481495
Microscopy: Asci and Spores (@1000)
481491
Part of the next photo;
481492
Specimen together with a Bacidia sp. on Quercus coccifera;
481493
Specimen together with a Bacidia sp. on Quercus coccifera;
481494
Microscopy: Asci and Spores (@1000)
481496
Microscopy: Asci and Spores (@1000)
481497
Microscopy: Asci and Spores (@1000)
481498
Microscopy: Asci and Spores (@1000);
481499
Microscopy: Asci and Spores (@1000);
481500
Microscopy: Asci and Spores (@1000);
481501
Microscopy: Apothecial sections (@100);
481502
Microscopy: Apothecial section in water (up) and after the addition of K (bottom) (@400);

Proposed Names

58% (1)
Eye3 Eyes3
Used references: British Flora: Smith et al. (Eds.), The Lichens of Great Britain and Ireland, the British Lichen Society, 2nd ed., 2009.

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Eye3 = Observer’s choice
Eyes3 = Current consensus

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Created: 2014-11-13 12:46:13 HST (-1000)
Last modified: 2014-11-13 12:53:42 HST (-1000)
Viewed: 25 times, last viewed: 2016-04-11 11:50:00 HST (-1000)
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