Lichens of southern Africa's Journal

On iNaturalist we already have a field

Lichen substrate

Substance lichen is growing on. Please use "Host" field to designate species of a living substrate.
https://www.inaturalist.org/observation_fields/189
Allowed values:
unknown 952
bark 6513
wood 713
moss 182
rock 2797
soil 365
leaves 227
artifact 151
bone 13
animal 18

also:

Fungi and Lichen: Substrate

What is the fungus or lichen growing on or in?
https://www.inaturalist.org/observation_fields/11447
Allowed values:
na 7825
soil 467
rock 49
wood and leaf litter 438
unsure 41

There are other fields (lots related to Lichens, many duplicates - see https://www.inaturalist.org/observation_fields?commit=Search&page=2&q=lichen&utf8=%E2%9C%93)

However, it seems that surely the substrate "Rock" (and indeed soil?) is probably crucial - as important as the category rock itself.

There are several "open" fields for Rock Type, but these are problematic. Under geology, we have several, but none are comprehensive (and how comprehensive do we need to be?).
https://www.inaturalist.org/observation_fields/319
https://www.inaturalist.org/observation_fields/2753
https://www.inaturalist.org/observation_fields/7443 (Protea Atlas & CREW - s Afr)

respectively these are:

• Not Applicable: 269 | 0 | 0
• Unknown: 0 | 23 | 12
• Other: 0 | 3 | 24

Sandstone: 202 | 62 | 831
Tertiary Sands: 0 | 0 | 150 Applicable to geology? But Namib Desert!
Limestone 11 | 5 | 66
Shale: 0 | 1 | 65
Granite 0 | 0 | 25
Ferricrete: - | - | 13
Silcrete: - | - | 12 How does one distinguish this from Ferricrete - merge?
Silt-clay-stone 11 | - | - What does this mean - scrap!
Quartzite 0 | 4 | 7 But is it really so easy to tell "sandstone" from "quartzite" - and what about Quartz?
Conglomerate: - | - | 9 Rather code for the constituent geology, unless not specific?
Dolerite: 0 | 0 | 7
Basalt 3 | 2 | 1
Alluvials - | 2 | - What does this mean? (either soil or sand/conglomerate) - scrap!
Dolomite 0 | - | -
Serpentine 0 | - | -

Others (not used in any projects) - these seem to be superfluous (some being metamorphosed versions of the above)
Volcanic
Schist
Gneiss
Marble
Chert
Chalk
Gypsum
Andesite
Diorite
Ultrabasics

Your thoughts??

https://archive.bgbm.org/BGBM/STAFF/Wiss/Sipman/keys/Afroxantkey3a.pdf

Compiled Key to Xanthoparmelia in Southern Africa
by H. Sipman, 25 Nov. 2017
The key is based on the keys for the genera Karoowia, Paraparmelia, Xanthoparmelia and the Neofuscelia group published by Hale (1989), Elix (201), Hale (1990) and Esslinger (1977), respectively. The species not known from Southern Africa are omitted, some rearrangements are made, and added are all additional species reported by Fryday (2015) in the Checklist for South Africa. For the added species a reference to a description is given; for the other species descriptions can be found in the above publications. The delimitation of the genus Xanthoparmelia follows Blanco et al. (2004). Genus abbreviations: K = Karoowia; N = Neofuscelia; P = Parmelia; Par = Paraparmelia; X = Xanthoparmelia. For the currently accepted name of the species, see the websites of Index Fungorum or Mycobank.

Key to main groups (coinciding largely with former genera)

1. Thallus loosely adnate, attached by central umbicilus.................................................. Xanthomaculina
   1' Thallus loosely or tightly adnate, attached by rhizines or scattered hapters ... goto 2

2. Thallus upper surface with pseudocyphellae .................................................................. Namakwa
   2' Thallus upper surface without pseudocyphellae ... goto 3

3. Thallus upper cortex with atranorin or usnic acid, colour whitish-, yellowish- or greenish grey ... goto 4
   3' Thallus upper cortex without atranorin or usnic acid; thallus colour dark brownish grey. ... goto 6

4. Thallus upper cortex with atranorin, upper surface whitish grey, K + pale yellow ........... Paraparmelia
   4' Thallus upper cortex with usnic acid, upper surface yellowish to greenish grey, K - ... goto 5

5. Thallus tightly adnate, subcrustose, often with immersed (aspicilioid) apothecia, with dull upper surface without or with thin epicortex ...... Karoowia
   5' Thallus tightly or loosely adnate, subcrustose or foliose to pulvinate, with sessile apothecia with constrated base, usually with glossy upper surface at least near the lobe tips, occasionally pruinose to scabrose. .... (Xanthoparmelia) ... goto 7

6. Thallus subfruticose, with linear, erect to spreading, not adnate lobes................ Almbornia
   6' Thallus foliose to subcrustose, with shorter, subirregular to sublinear, loosely to tightly adnate lobes .... Neofuscelia

7. Thallus upper surface dull, at the lobe tips coarse-pruinose .................... Pruinose Xanthoparmelia
   7' Thallus upper surface shiny, at least at the lobe tips, rarely thinly white-pruinose.. ... goto 8

8. Thallus sorediate........................................................................................... Sorediate Xanthoparmelia
   8' Thallus not sorediate ... goto 9

9. Thallus terricolous (on soil, humus or pebbles, attached or vagrant) .... Terricolous Xanthoparmelia
   9' Thallus saxicolous, rarely on other substrate ... goto 10

10. Thallus isidiate ... goto .11
    10' Thallus not isidiate . ... goto 12

11. Thallus with pale brown to brown lower surface, darkest at the tips .......Isidiate Xanthoparmelia pale below
    11' Thallus with black lower surface, paler at the tips ....................................... Isidiate Xanthoparmelia black below

12. Thallus with pale brown to brown lower surface, darkest at the tips ........ Nonisidiate, Nonsorediate Xanthoparmelia pale below
    12' Thallus with black lower surface, paler at the tips ......................................... Nonisidiate, Nonsorediate Xanthoparmelia black below

see article for keys for the different groupings.

A PDF copy of the book Macrolichens of East Africa is available to download at https://nhm2.uio.no/botanisk/cgi-bin/rll.pl?sq=0&db=RLL&rn=18091.

Some of the nomenclature is out of date, especially in Parmeliaceae, and the treatments of some genera (especially Xanthoparmelia!) should not be applied to southern Africa, but this book is still an important resource for southern African lichenology.