Cladonia / Erioderma / Porina / Pyrenula

Provisional illustrated key to the lichen genus Cladonia on La Réunion
by H. Sipman, 24 May 2011

NOTE: The present key is provisional. The identification of some species is uncertain and the delimitation between a few species is unclear. Ahti (pers. comm.) suggests that a few undescribed species are present on the island.

1a Podetia absent; squamules present only - - - 2
1b Podetia present; squamules present or absent - - - 5

2a (2) Squamules with bright yellowish tinge, yellow below, containing usnic acid, elongated, to 1 cm long and 1 mm wide - - - C. insignis
2b Squamules dull greenish grey, white below, lacking usnic acid, elongated or not - - - 3

3a (2) Squamules long, to over 10 mm long, often with white marginal cilia, P+ yellow (psoromic acid); rare species - - - C. ceratophylla
3b Squamules short, to about 3 mm long, without marginal cilia, P+ red (fumarprotocetraric acid); common species (juvenile stages of various species may key out here, only two more regularly podetium-less species are treated) - - - 4

4a (3) Squamules rounded without deciduous lobules - - - C. centrophora
4b Squamules crenulated with deciduous lobules - - - C. mauritiana

5a (1) Squamules absent or very scarce and inconspicuous, occasionally more numerous on fallen podetia; podetia usually densely branched - - - 6
5b Squamules present, usually conspicuous and abundant; podetia simple or scarcely to moderately branched - - - 15

6a (5) Podetia completely without cortex, with felty surface, densely branched; squamules completely absent - - - 7
6b Podetia at least partly corticate and with smooth surface, more or less branched, occasionally absent; squamules present or absent - - - 8

7a (6) Podetia pale yellowish to greenish grey, K- (usnic, perlatolic acids); trichotomies often present (when lacking, cf. C. medusina) - - - C. confusa
7b Podetia whitish grey or with brownish spots, K+ yellow (thamnolic acid); branchlets often combed, looks like C. rangiferina - - - C. gigantea

8a (6) Thallus with yellowish to greenish tinge, containing usnic acid - - - 9
8b Thallus dull grey to brown, lacking usnic acid - - - 13

9a (8) Podetia 2-4 mm wide except near the tips - - - C. candelabrum
9b Podetia mostly under 1(-2) mm wide - - - 10

10a (9) Main stems 0.8-2 mm wide, upright - - - 11
10b All parts of the podetia under 0.8 mm wide, except when bearing apothecia, often straggling - - - 12

11a (10) Podetium axils perforate; thallus squamules absent - - - C. perrieri
11b Podetium axils closed; some thallus squamules present in basal parts - - - C. pachyclados

12a (10) Podetia corticate, with smooth surface; squamatic or thamnolic acid present - - - C. peltasta
12b Podetia largely ecorticate, with partly felty surface; barbatic or perlatolic acid present - - - C. medusina

13a (8) Podetia scarcely branched, densely bundled, c. 1 cm tall; atranorin present alone (or perhaps with fatty acid) - - - C. mascarena
13b Podetia richly branched with patent branchlets, several cm tall; atranorin absent - - - 14

14a (13) Thallus K+ yellow, P+ yellow (thamnolic acid) - - - C. glaucopallida
14b Thallus K-, P- (barbatic acid) - - - C. hedbergii

15a (5) Podetia apically with disc- or cup-shaped widenings, unbranched but sometimes regenerating from the apical widening and with two or more tiers of widenings, or with secondary lateral or apical branches - - - 16
15b Podetia cylindrical with acuminate tips, often branchy - - - 28

16a (15) Apical widenings perforated, with the podetial cavity exposed - - - 29
16b Apical widenings closed - - - 17

17a (16) Podetia proliferating from the centre of disc-like widenings or from both centre and margin - - - 18
17b Podetia proliferating only from the margin of cup-like widenings or not proliferating - - - 19

18a (17) Podetia between widenings thick and cylindrical, c. 0.8-1 mm diam., widenings to 3 mm, whitish to brownish (fumarprotocetraric acid) - - - C. centrophora
18b Podetia thinner, usually around 0.5 mm, widenings to 5 mm, brownish (fumarprotocetraric acid) - - - C. andesita

19a (17) Apical podetium widenings more than three times as wide as stalk, distinctly cup- or bowl-shaped; stalk (cylindrical part of podetium) short, about 1-3(-5) times as long as cup - - - 20
19b Apical podetium widenings mostly up to twice as wide as stalk, often restricted to a small apical thickening or disk; cylindrical part of podetia dominant and usually over 10 times as long as cup - - - 23

20a (19) Thallus with yellowish tinge, containing usnic acid; apothecia red - - - 21
20b Thallus dull grey to brown, lacking usnic acid; apothecia brown - - - 22

21a (20) Podetium cups inside and often also outside with deciduous granules or scales; squamules small, up to 1 mm long, often orange below near base - - - C. coccifera
21b Podetium cups smooth; squamules large, to over 10 mm long, not orange below near base - - - C. insignis

22a (20) Podetium cups largely corticate, with smooth or somewhat scaly wall, often with longitudinal fissures; apothecia on long stalks sometimes exceeding the cup length - - - C. intermediella
22b Podetium cups largely decorticated, finely sorediate or granular, without longitudinal fissures; apothecia short-stalked - - - C. subsquamosa

23a (19) Podetia sorediate, at least near the tips - - - 24
23b Podetia not sorediate, sometimes with deciduous granules or scales - - - 26

24a (23) Soralia in diffuse patches below the cups or covering most of the podetia; apical widenings distinctly cup-shaped and often with lateral slits - - - C. borbonica
24b Soralia different; apical widenings irregular, without lateral slits - - - 25

25a (24) Podetia corticate at base, continuously sorediate above except near apical widenings, often with rounded soralia at the transition - - - C. ochrochlora
25b Podetia mostly corticate, with convex sorediate patches restricted to parts of the apical widening and the primary squamule tips - - - C. leucophylla

26a (23) Podetia K+ yellow, without deciduous granules or scales, continuously corticate but maybe somewhat warty (atranorin, fumarprotocetraric acid) - - - C. submultiformis
26b Podetia K-, with deciduous granules or scales which leave denudated patches (no atranorin, with fumarprotocetraric or psoromic acid) - - - 27

27a (26) Podetia largely corticate and spotwise with deciduous granules, mainly just below the scyphi, leaving decorticated spots (psoromic or fumarprotocetraric acid) - - - C. fruticulosa
27b Podetia largely and densely covered by deciduous granules and scales leaving much of the podetia decorticated (fumarprotocetraric acid) - - - C. mauritiana

28a (15) Podetia branching with conspicuous perforated axils exposing the podetial cavity, at least at the top of the podetia - - - 29
28b Podetia branching or not, without wide, perforated axils in the top of the podetia - - - 30

29a (16, 28) Thallus with yellowish to greenish tinge, containing usnic acid - - - C. boivinii
29b Thallus dull grey to brown, lacking usnic acid - - - C. squamosa

30a (28) Podetia regularly branching over their whole length, with furcate tips - - - 31
30b Podetia unbranched, or with few apical branches or with few secondary, lateral branches - - - 35

31a (30) Podetia with deciduous granules and scales, finally completely decorticated - - - C. subdelicatula
31b Podetia not producing propagules, most of the surface persistently corticate - - - 32

32a (31) Podetia with small squamules to near the tips, somewhat decorticate between these squamules - - - 33
32b Podetia without squamules in apical parts, corticated throughout - - - 34

33a (32) Thallus often with pale yellowish tinge, containing usnic acid - - - C. varians
33b Thallus dull grey to brown, lacking usnic acid - - - C. diplotypa

34a (32) Podetia less than 0.5 mm thick, straggling - - - C. cinereorubens
34b Podetia with upright stems up to 1 mm thick - - - C. perplexa

35a (30) Podetia producing soredia or deciduous granules or scales, finally largely decorticated, often without apothecia - - - 36
35b Podetia not producing propagules, persistently corticate, often with apothecia - - - 41

36a (35) Podetia sorediate, at least near the tips - - - 37
36b Podetia not sorediate, producing deciduous granules and scales - - - 39

37a (36) Podetia completely decorticated and surface sorediate or abraded; hymenial discs red; K+ yellow or K- (thamnolic or squamatic acid with or without barbatic acid) - - - C. macilenta
37b Podetia corticate below, sorediate above; hymenial discs brown; K+ pale yellow or K- (with or without atranorin) - - - 38

38a (37) Decorticated parts of podetia brownish, K- (atranorin absent) - - - C. ochrochlora
38b Decorticated parts of podetia white, K+ pale yellow (atranorin) - - - C. praetermissa

39a (36) Podetia producing deciduous, corticate squamules only - - - 40
39b Podetia producing small, more or less ecorticate squamules and granules - - - C. mauritiana

40a (39) Primary squamules few mm long, without cilia; denudated podetia becoming brownish, glossy and pellucid; apothecia common, red - - - C. didyma
40b Primary squamules large, to over 10 mm long, usually dominant, often with white marginal cilia; denudated podetia whitish, smooth; apothecia rare, brown - - - C. ceratophylla

41a (35) Apothecia brown; all podetia with apical apothecia, often with longitudinal slits - - - C. peziziformis
41b Apothecia red; podetia often without apothecia, without longitudinal slits - - - C. didyma

Indicated are synonyms used for Reunion records, number of studied specimens and chemistry of Reunion material, and total distribution. Names in bold indicate species of which the type specimen originates from Reunion. Locality name (Reunion) in bold means known only from Reunion. A click on the picture brings a higher resolution.

1. Cladonia andesita Vain. - 4 coll.; fumarprotocetraric acid; 1980-2400 m; mainly Neotropical-Andean, also reported from East Africa (Swinscow & Krog 1988).

Cladonia andesita (Follmann s.n.).

2. Cladonia boivinii Vain. - 6 coll.; usnic, squamatic acid; 1500-2820 m; Comores, Reunion, Madagascar (Abbayes 1947). - Differs from C. squamosa only by presence of usnic acid.

Cladonia boivinii (Follmann s.n.).

3. Cladonia borbonica Nyl. - 2 coll.; fumarprotocetraric acid; 1500-1700 m; Reunion, South and East Africa (Swinscow & Krog 1988 as C. poeciloclada), Madagascar (Ahti & Aptroot 1992).

Cladonia borbinica (Kalb 26302).

4. Cladonia candelabrum (Bory) Nyl. - 8 coll.; usnic acid alone or with squamatic and/or barbatic acid; 1980-2520 m; Reunion only (type locality).

Cladonia candelabrum (Follmann s.n.).

5. Cladonia centrophora Müll. Arg. (syn. Cladonia ceratophyllina (Nyl.) Vain. in Hue) - 15 coll.; fumarprotocetraric acid; 1210-2520 m; East and South Africa (Swinscow & Krog 1988), Madagascar, Reunion (are both conspecific?).

Cladonia centrophora, specimen with many tiers and a smooth surface (Brand 58833).	Cladonia centrophora, specimen with few tiers and party warty and decorticated surface (Follmann s.n.).

6. Cladonia ceratophylla (Swartz) Sprengel - reported by Nylander (1859: 249); widespread in the Neotropics, also reported from Reunion and India (Ahti 2000).

Cladonia ceratophylla from Aymatoi savanna, Guyana (Sipman 39947).

7. Cladonia cinereorubens Abbayes - 2 coll.; squamatic acid; 510-560 m; Madagascar (Abbayes 1947).

Cladonia cinereorubens (v. d. Boom 39947).

8. Cladonia coccifera (L.) Willd. - 1 coll.; usnic acid, zeorin; 2000 m; Northern hemisphere, tropical mountains (Ahti 2000).

Cladonia coccifera, young podetia (Schiefelbein 1691).

9. Cladonia confusa R. Sant. (syn. Cladonia leptoclada Abbayes) - 7 coll.; usnic, perlatolic acids; 1300-2520 m; pantropical mountains (Ahti 2000).

Cladonia confusa (Kalb 33797).

10. Cladonia didyma (Fée) Vain. - 17 coll.; didymic acid; didimic, thamnolic acids; thamnolic, barbatic acids; 1360-2400 m; pantropical, extending into warm-temperate zones (Ahti 2000).

Cladonia didyma (Kalb 33732).

11. Cladonia diplotypa Nyl. - not yet known from La Reunion; tropical continental Africa (Ahti 1977).

Cladonia diplotypa from Rwanda (Lambinon 72/Rw/396).

12. Cladonia fruticulosa Kremp. (syn. C. decaryana Abbayes, C. subpityrea Sandst.) - 4 coll.; psoromic acid; fumarprotocetraric acid; atranorin?; 5-2000 m; Palaeotropics (Swinscow & Krog 1988).

Cladonia fruticulosa (Kalb 25957).

13. Cladonia gigantea (Bory) H. Olivier (C. rangiferina Auct. Borbon., non (L.) F.H. Wigg.) - 3 coll.; thamnolic acid; 1600-2030 m; Reunion, Mauritius, Madagascar, Malawi (Ahti 1977).

Cladonia gigantea (Brand 58908).

14. Cladonia glaucopallida Vain. (syn. C. gorgonina Auct., non (Bory) Eschw.) - 3 coll.; thamnolic acid; 1740-1890 m; Reunion, Madagascar (Ahti 1977).

Cladonia glaucopallida (Brand 58907).

15. Cladonia hedbergii Ahti - 4 coll.; barbatic acid; 2300-2400 m; East Africa (Ahti 1977).

Cladonia hedbergii (Follmann s.n.).

16. Cladonia insignis Nyl. - 8 coll.; usnic, hypothamnolic acids; 1740-2400 m; Reunion endemic (Stenroos 1991).

Cladonia insignis (Schiefelbein 1611).

17. Cladonia intermediella Vain. - 3 coll.; fumarprotocetraric acid; 1300-2250 m; East Africa, Reunion, Mauritius (Swinscow & Krog 1988). Resembles the boreal C. pocillum and C. pyxidata closely and replaces them in tropical Africa.

Cladonia intermediella (Kalb 25179).

18. Cladonia leucophylla Ahti & Krog - 4 coll.; homosekikaic acid; 1220-2450 m; East Africa (Swinscow & Krog 1988).

Cladonia leucophylla, podetia (Schiefelbein 1668).	Cladonia leucophylla, primary thallus (v. d. Boom 39751).

19. Cladonia macilenta Hoffm. - 7 coll.; thamnolic acid; barbatic acid; barbatic, thamnolic acids; 800-1700 m; cosmopolitan (Ahti 2000).

Cladonia macilenta (Follmann s.n.).

20. Cladonia mascarena Nyl. - 3 colls.; atranorin; atranorin, rangiformic acid?; 1740-2030 m; Reunion (type).

Cladonia mascarena (Brand 58914).

21. Cladonia mauritiana Ahti & J.C. David - 14 coll.; fumarprototocetraric acid; 5-2230 m; Mauritius (David & Hawksworth 1995).

Cladonia mauritiana, simple podetia (Follmann s.n.).	Cladonia mauritiana, branched podetia (Follmann s.n.).

22. Cladonia medusina (Bory) Nyl. - 14 coll.; usnic, squamatic acid; usnic, boninic? acids; usnic, thamnolic acids; usnic, barbatic? acids; 1380-2335 m; Tanzania, Madagascar, Reunion (Swinscow & Krog 1988).

Cladonia medusina (v. d. Boom 40317).

23. Cladonia ochrochlora Flörke - 2 colls.; fumarprotocetraric acid; 2050 m; cosmopolitan (Ahti 2000)

Cladonia ochrochlora (Follmann s.n.).

24. Cladonia pachyclados (Vain.) Ahti - 5 colls.; usnic, barbatic acids; 2230 m. (identification uncertain while grayanic acid absent); East Africa, Madagascar, Reunion (Swinscow & Krog 1988). The material may be heterogeneous.

Cladonia pachyclados (Follmann s.n.).	Cladonia pachyclados (Follmann s.n.).
Cladonia pachyclados, fruiting, swollen podetia (Follmann s.n.).

25. Cladonia peltasta (Ach.) Sprengel - 23 coll.; usnic, barbatic? acids; usnic, homosekikaic? acids; usnic, perlatolic? acids; 1000-2820 m; Reunion, Comores, Madagascar (Ahti & Aptroot 1992).

Cladonia peltasta (Follmann s.n.).	Cladonia peltasta?, swollen, fertile podetia (Follmann s.n.).

26. Cladonia perplexa Abbayes - reported by Ahti & Aptroot (1992: 122); Madagascar, Reunion (Ahti & Aptroot 1992).

27. Cladonia perrieri Abbayes - 6 colls.; usnic, thamnolic acids; usnic, squamatic acids; 1940-2520 m; Madagascar (Abbayes 1947).

Cladonia perrieri (v. d. Boom 40543).

28. Cladonia peziziformis (With.) J.R. Laundon - 2 colls.; fumarprotocetraric acid; 1400-2335 m; Cosmopolitan (Ahti 2000).

Cladonia peziziformis (v. d. Boom 39962).

29. Cladonia praetermissa A.W. Archer - 1 coll.; atranorin; 1400-1450 m; palaeotropical? (Ahti & Aptroot 1992).

Cladonia praetermissa (Sérusiaux 2008-12).

30. Cladonia squamosa Hoffm. - 9 colls.; squamatic acid; 950-2335 m; cosmopolitan (Ahti 2000). - Differs from C. boivini only by absence of usnic acid.

Cladonia squamosa (v. d. Boom 40418).

31. Cladonia subdelicatula Vain. ex Asahina - 4 colls.; thamnolic acid; 510-1600 m; neotropical (Ahti 2000).

Cladonia subdelicatula (v. d. Boom 40089).

32. Cladonia submultiformis Asah. - 2 colls.; atranorin, fumarprotocetraric acid; c. 1900 m; palaeotropical? (Swinscow & Krog 1988).

Cladonia cf. submultiformis (Follmann s.n.).	Cladonia submultiformis from Mt. Kinabalu, Malaysia (Sipman & Tan 31372).

33. Cladonia subsquamosa Kremp. - 10 colls.; fumarprotocetraric acid; 1360-2335 m; pantropical (Ahti 2000).

Cladonia subsquamosa (v. d. Boom 39955).	Cladonia subsquamosa from Mt. Aymatoi, Guyana (Sipman 39838).

34. Cladonia varians Vain. ex Ahti - 6 colls.; usnic, squamatic acids; usnic, barbatic acids; usnic, thamnolic acids; usnic, squamatic, thamnolic acids; 700-2450 m; Tanzania, Madagascar, Reunion, Mauritius (Ahti & Aptroot 1992).

Cladonia varians (Sérusiaux 2008-16).	Cladonia varians (Brand 58909).

Relevant references:

Abbayes, H. des 1947: Cladonia (Lichens) nouveaux de la Région Malgache. Revue Bryologique et Lichénologique 16: 74-94.

Abbayes, H. des 1964: Deux Cladonia (Lichens) nouveaux d'Afrique Australe. Revue Bryologique et Lichénologique 33 (1-2): 235-239.

Ahti, T. 1977: The Cladonia gorgonina group and C. gigantea in East Africa. Lichenologist 9: 1-15.

Ahti, T. 1986: New species and nomenclatural combinations in the lichen genus Cladonia. Annales Botanici Fennici 23: 205-220.

Ahti, T. 2000: Cladoniaceae. Flora Neotropica Monograph 78. Organization for Flora Neotropica and New York Botanical Garden, Bronx. 362 pp.

Ahti, T. & Aptroot, A. 1992: Lichens of Madagascar: Cladoniaceae. Cryptogamie, Bryologie-Lichénologie 13 (2): 117-124.

Ahti, T., Krog, H. & Swinscow, T. D. V. 1987: New or otherwise interesting Cladonia species in East Africa. Annales Botanici Fennici 24: 85-94.

Archer, A. W. 1984: Three new Australian lichens: Cladonia celata, C. praetermissa and C. wilsonii. Muelleria 5: 271-275.

David, J. C. & Hawksworth, D. L. 1995: Lichens of Mauritius I: some new species and records. Pp. 93-111 in: Knoph, J.-G., Schrüfer, K. & Sipman, H. J. M. (eds.): Studies in Lichenology with Emphasis on Chemotaxonomy, Geography and Phytochemistry. Festschrift Christian Leuckert. Bibliotheca Lichenologica 57. J. Cramer, Berlin, Stuttgart.