Heterodermia

Mongkolsuk, Pachara, Meesim, Sanya, Poengsungnoen, Vasun, Buaruang, Kawinnat, Schumm, Felix & Kalb, Klaus, 2015, The lichen family Physciaceae in Thailand-II. Contributions to the genus Heterodermia sensu lato, Phytotaxa 235 (1), pp. 448-450 : 448-450

Key to some common worldwide species of Heterodermia s.str.

(TLC, at least in solvent A is necessary for definitive identification)

1. Thallus without vegetative propagules .................................................................................................................................. 2

- Thallus with isidia, phyllidia or soralia.................................................................................................................................. 9

2. Medulla at least partly yellowish, orange or brownish yellow, K+ purple ............................................................................ 3

- Medulla completely white...................................................................................................................................................... 5

3. Medulla with dissectic acid......................................................................................... H. albidiflava (Kurok.) D.D. Awasthi

- Medulla without dissectic acid............................................................................................................................................... 4

4. Lobes 0.3–1.2 mm wide, apothecia 0.5–2.2 mm wide, India, Nepal, Thailand.............................. H. firmula (Nyl.) Trevis.

- Lobes 0.7–2 mm wide, apothecia 1.5–6 mm wide, North America: Texas, Mexico............ H. rugulosa (Kurok.) Wetmore

5. Medulla without depsidones, only terpenes present ..................................................... H. diademata (Taylor) D.D. Awasthi

- Medulla with both terpenes and depsidones .......................................................................................................................... 6

6. Medulla with salazinic and hypoconstictic acids ........................................................................ H. tropica (Kurok.) Sipman

- Medulla without salazinic and hypoconstictic acids .............................................................................................................. 7

7. Medulla without dissectic acid, with norstictic acid, with small lateral lobules and pseudocyphellae ................................... .................................................................................................................................... H. rubescens (Räsänen) D.D. Awasthi

- Medulla with dissectic acid, norstictic acid present or absent ............................................................................................... 8

8. Medulla K+ dark yellow; norstictic acid absent ........................................................................................... H. verdonii Elix

- Medulla K+ yellow then red; norstictic acid present ........................................... H. angustiloba (Müll. Arg.) D.D. Awasthi

9. Thallus sorediate .................................................................................................................................................................. 10

- Thallus with isidia or phyllidia ............................................................................................................................................ 13

10. Medulla without depsidones, only terpenes present.............................................................................................................11

- Medulla with depsidones...................................................................................................................................................... 12

11. Lobes linear-elongate, spores 30–37 × 14–18 µm, 16β-acetoxyhopane-6α,22-diol absent....... H. speciosa (Wulfen) Trevis

- Lobes short, often flexuose-bent, spores 23–32 × 12–14 µm, 16β-acetoxyhopane-6α,22-diol present as major terpene....... .................................................................................................................................... H. tremulans (Müll. Arg.) W.L. Culb.

12. Medulla with hypoconstictic and salazinic acids, soralia ± linear and continuous along margins of the lobes, not apical..... ..................................................................................................................................... H. albicans (Pers) Swinscow & Krog

- Medulla without hypoconstictic and salazinic acids, but with norstictic acid (major), soralia apical on main lobes and on short lateral lobes, in delimited areas, ± labriform................................................... H. pseudospeciosa (Kurok.) W.L. Culb.

13. Thallus with distinct isidia ................................................................................................................................................... 14

- Thallus with phyllidia, sometimes becoming sorediate-isidiate-granular............................................................................ 16

14. Medulla with both salazinic and hypoconstictic acids ........................................... H. antillarum (Vain.) Swinscow & Krog

- Medulla with or without salazinic acid but lacking hypoconstictic acid ............................................................................. 15

15. Medulla with salazinic acid, isidia mostly laminal ............................................................ H. granulifera (Ach.) W.L. Culb.

- Medulla without salazinic acid, with terpenes only, isidia mostly marginal......... H. isidiophora (Vain.) Swinscow & Krog

16. Medulla with dissectic acid, with or without norstictic acid................................................................................................ 17

- Medulla without dissectic acid............................................................................................................................................. 18

17. Norstictic acid present...................................................................................................... H. dissecta (Kurok.) D.D. Awasthi

- Norstictic acid absent ....................................................................................................................... H. koyana (Kurok.) Elix

18. Norstictic acid present.............................................................................................................................. H. coralloidea Elix

- Norstictic acid absent, with terpenes only............................................................................................................................ 19

19. Thallus 2–5 cm wide, lobes 0.1–0.5 mm wide, phyllidia becoming sorediate-isidiate-granular; medulla with 6α-acetoxyhopane-16β,22-diol present as major terpene....................................................................................... H. isidiophorella Elix

- Thallus 5–20 cm wide, lobes 0.7–2.5 mm wide, phyllidia not becoming sorediate-isidiate-granular; medulla with 16β-acetoxyhopane-6α,22-diol present as major terpene .................................................................... H. lepidota Swinscow & Krog