Observation 196846: Endocarpon Hedwig
When: 2015-01-17
Who: zaca
No herbarium specimen

Notes: Growing on siliceous rock.
To arrive to the genus Thelenella I used the key in Ref. 1, on the account of the following choices:
1 – Photobiont a green alga, or absent;
2 – Asci with (1-)2-8 spores;
3 – Thallus various; if the hyphal nature is clearly apparent, then hyphae immersed in the substratum, colourless, or narrower;
4 – Hamathecium at least partly comprising interascal filaments, these rarely absent, and then hymenial gel I- or I+ faint blue;
5 – Ascospores septate or muriform, rarely simple and then narrowly fusiform;
6 – Asci with the wall thickened above, if unthickened then growing on bark (interascal filaments various; photobiont present or absent);
7 – Ascospores broadly to narrowly ellipsoid, 2-5 times as long as wide, 1- to multiseptate or muriform;
8 – Ascomatal wall shades of brown or green-brown, but not bright green;
9 – Ascospores >3-septate, or submuriform or muriform;
10 – Ascospores with walls more or less equally and not strongly thickened;
11 – Ascospores colourless (sometimes faintly brown when old);
12 – Photobiont green, not trentepohlioid;
13 – Ascus wall and hymenial gel I-
—> Thelenella.
Let me say that some of the choices were not particularly clear to me: – 4 – (I didn’t observe interascal filaments); – 6 – (the alternative leads to the genus Psoroglaena, which seems improbable).
This genus has three species (one with two varieties) reported in Ref. 1 with the following features:
T. muscorum – var. muscorum: Asci 2–4-spored, ascospores 60–110 μm long; – var. octopora: Asci 8-spored, ascospores (50–)55–65 × 14.5–19 μm;
T. modesta: Asci 4–8-spored, ascospores (20–)25–42 × (9–)11–17 μm;
T. larbalestieri: Asci 8-spored, ascospores 44–69 × 13–15 μm.
Thanking into account that I only observed 2-spored asci, the most promising is T. muscorum var. muscorum; However, the spores are too small for that (I obtained values in the ranges 46 – 69 × 15-22 µm with average Me = 52.8 × 19.2 µm); on the other hand, the spores are too fat for T. larbalestieri, which has 8-spored asci, and too fat for T. modesta, which has 4–8-spored asci.
Let me also mention that the British Flora (Ref. 2) refers the same species in the genus Thelenella.
So, either I got the wrong genus or this is a undiscribed species.

EDITED:
I think that took the wrong key: The above reasoning should apply to CRUSTOSE pyrenocarpous (Key B in Ref.1), whereas my specimen has a thallus that can be considered squamulose. Using the appropriate key (Key A), one gets:
1 – Photobiont a green alga;
2 – Thallus squamulose or foliose, attached to substratum by rhizohyphae, rhizines or holdfasts, lower cortex often present
3 – Hymenium containing photobiont cells; ascospores muriform, 1–2 per ascus
—→ Endocarpon.
This genus has three species reported in Ref. 1 with the following features:
Endocarpon adscendens: Asci 2-spored, ascospores (29–)31.5–40(–51) × (10.5–)12.5–16(–17.5) μm;
Endocarpon pallidum: Asci 2-spored, ascospores (25–)34.5(–49.5) × (14.5–)16(–19) μm;
Endocarpon pusillum: Asci 2-spored, ascospores (29.5–)44(–58) × (14–)19(–28) μm.
Again there is a problem related with the dimensions of the spores and no conclusion can be drawn.

Images

501159
501160
501161
501162
Microscopy: Perithecial section;
501163
Microscopy: Asci and spores;
501164
Microscopy: Other perithecial sections;
501165
Microscopy: Details.

Proposed Names

3% (2)
Eye3
Used references: Ref. 1: Alan Orange, British and Other Pyrenocarpous Lichens, Version 2, August 2013 (available from http://www.museumwales.ac.uk/3103/)
Ref. 2 = British Flora: Smith et al. (eds.), The Lichens of Great Britain and Ireland, The British Lichen Society, 2nd ed., 2009.
Based on microscopic features
29% (1)
Eye3 Eyes3
Recognized by sight

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Eye3 = Observer’s choice
Eyes3 = Current consensus

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Created: 2015-01-22 06:52:42 PST (-0800)
Last modified: 2015-01-22 09:08:07 PST (-0800)
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