Lichen determination keys - neotropical genera -

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Key to fruticose or dimorphic lichens

1a Lichens dimorphic, composed of a fruticose part and a crustose or squamulose part; fruticose thallus containing algae or not, usually producing ascocarps or basidia; crustose or squamulose thallus containing algae, not producing ascocarps or basidia (NOTE: isidia are not a fruticose thallus part)---2
1b Lichens uniformly fruticose; fruticose thallus containing algae, and ascocarps, if present---21

2a Fruticose thallus without algae, producing basidia (basidiocarp), subulate or mushroom-shaped---3
2b Fruticose thallus often with algae, producing ascocarps, often branched ("podetia")---6

3a Fruticose thallus subulate---4
3b Fruticose thallus mushroom-shaped---Omphalina

4a Algae-containing thallus crustose---5
4b Algae-containing thallus squamulose---Lepidostroma

5a Fruticose thallus 2-4 x 0.2-0.4 mm; basidia 6-8-spored---Clavulinopsis
5b Fruticose thallus usually over 1 cm long---Multiclavula

6a Primary thallus crustose; podetia mostly not branched and bearing a single apothecium---7
6b Primary thallus squamulose; podetia often branched and often without apothecia---10

7a Apothecia lateral, elongate---Icmadophila
7b Apothecia terminal, disc-like to globose---8

8a Cephalodia present on crustose thallus---Pilophorus
8b Cephalodia absent---9

9a Apothecia brown, when young with flat disc and distinct margin---Baeomyces
9b Apothecia whitish to pink, usually with convex disc and thin or disappearing margin---Dibaeis

10a Fruticose thallus branches hollow, often branched and without ascocarps; ascocarps red or brown---Cladonia
10b Fruticose thallus branches solid, usually unbranched and with terminal ascocarp; ascocarps pink---Phyllobaeis

21a (1) Thallus branches hollow---22
21b Thallus branches solid, with arachnoid or more compact central tissue---30

22a Thallus surface glossy, pale brown to brown, with usually frequent perforations or pseudocyphellae; terrestrial, occasionally on mossy tree trunks---23
22b Thallus surface dull, usually whitish, greenish or greyish; perforations usually absent or restricted to axils of ramifications---24

23a Branches 0.5-2 mm thick; true perforations present---Cladia
23b Branches 0.2-0.5 mm thick; pseudocyphellae present, rarely perforated---Oropogon

24a Thallus branches with squamules, especially at the base---Cladonia
24b Thallus without such appendages---25

25a Epiphytic or on mossy banks; pseudocyphellae or tiny perforations frequent---26
25b Terrestrial, occasionally on decaying tree stumps or among mosses on rocks or trees; pseudocyphellae or tiny perforations absent---27

26a Thallus branches thin, rarely over 0.5 mm wide, whitish---Oropogon
26b Thallus branches thick, usually over 1 mm wide, greenish grey---Ramalina

27a Thallus richly branched, the branches connected by ca. 0.1 mm long anastomoses---Carassea
27b Thallus more or less branched, without anastomoses, the branches at most sticking to eachother where touching---28

28a Thallus whitish grey, subulate, with smooth surface---Thamnolia
28b Thallus greenish grey to brown, with smooth or tomentose surface; sometimes whitish spots present, these tomentose---29

29a Thallus surface slightly arachnoid, without cortex---Cladina
29b Thallus surface at least in part smooth, with thin cortex---Cladonia

30a Thallus branches with tough central strand, which stretches and becomes visible between the fragmenting outer layer by moderate pulling---Usnea
30b Thallus branches without tough central strand, breaking completely by pulling---31

31a Epiphytic species, occasionally on dead wood---32
31b Epilithic or epigaeic species, occasionally on mossy tree bases---45

32a Thallus branches flattened, usually over two times wider than thick---33
32b Thallus branches mainly cylindrical, or with scattered flattened sections---35

33a Thallus with ca. 0.1-0.2 mm long, stiff hairs composed of bundled hyphae; apothecium disc orange, K+ darkviolet; only on the pacific coast of Peru---Seirophora
33b Thallus not hairy; apothecium disc not orange (when orange, see Teloschistes)---34

34a Thallus greenish grey, over 2 cm long when full-grown, often pendant---Ramalina
34b Thallus whitish, c. 1 cm long when full-grown, erect; surface smooth---Siphula

35a Thallus, at least in part, yellow, K+ purple---Teloschistes
34b Thallus bluish grey or greenish to whitish yellow, K----36

36a Thallus greenish grey to brown; with green algae---37
36b Thallus bluish grey to black, basal branches sometimes whitish; branches more or less cylindrical; with blue-green algae---41

37a Thallus branches with granular to tomentose surface, grey to blue-grey---38
37b Thallus branches with smooth surface, greenish grey to brown---39

38a On thick tree trunks in rain shade in humid forest; branching dendroid with flattened terminal branchlets; widespread in montane forest---Leprocaulon
38b On shrub branches or exposed cliffs; branching more irregular; dry coastal areas of Peru and Chile---Tornabea

39a Thallus branches flattened, composed of chains of apothecia; rare, small lowland plant on twigs and leaves---Polystroma
39b Thallus branches usually several cm long, cylindrical; more or less widespread---40

40a Thallus brown; branches usually under 0.5 mm wide, slender and much branched; only at high elevations---Bryoria
40b Thallus greenish grey; branches usually over 0.5 mm wide; widespread (see also couplet 51-52)---Ramalina

41a With more or less scattered tomentum; no apothecia; thallus with multilayered cortex, not gelatinous---Dendriscocaulon
41b Without tomentum; no apothecia; thallus with multilayered cortex, not gelatinous---Coccocarpia
41c Without tomentum; apothecia usually present; thallus with cortex composed of single cell layer or without cortex, gelatinous---42

42a Richly branched; main branches up to 0.1 mm wide; apothecia common (upland); cortex composed of a single cellular layer; algae Scytonema, gelatinous---Polychidium
42b Sparingly branched; main branches over 0.1 mm wide, without tomentum; apothecia common; no cellular cortex; algae Nostoc in chains, gelatinous---Lempholemma

45a (30) Algae green; on various substrates---46
45b Algae blue-green; on rock in warm lowlands (provisional, incomplete treatment)---54

46a Fruticose thallus with granular, coralloid, cylindrical or squamulose phyllocladia; with green algae---47
46b Fruticose thallus without phyllocladia; algae blue-green or green---48

47a Surface of phyllocladia smooth---Stereocaulon
47b Surface of phyllocladia tomentose---Leprocaulon

48a On soil at high elevation---49
48b On rock or mossy tree trunks---51

49a Thallus whitish yellow, with loose, long and slender branches---Alectoria
49b Thallus whitish, with dense, short and blunt branches---50

50a Thallus branches flattened, scarcely branched, never with ascocarps (cf. also Toninia, with thallus composed of rounded, sometimes elongated, warts; recognizable by dark grey colour and frequent presence of apothecia)---Siphula
50b Thallus branches coralloid; mazaedium present---Acroscyphus

51a Thallus brown; branches rounded and much branched, under 0.5 mm thick---Bryoria
51b Thallus greenish grey to grey; branches more or less flattened, over 0.5 mm thick---52

52a Forming short mats among moss at high elevations; ascocarps black with mazaedium---Bunodophoron
52b Forming little shrubs with narrow holdfast on rock; ascocarps yellow to grey and without mazaedium---53

53a Near the coast only; thallus and ascocarps grey; cortex of palissadic structure; without cartilaginous strands---Roccella
53b Widespread; thallus greenish grey, apothecial disc yellowish; cortex of strongly conglutinated, periclinal hyphae; cartilaginous strands present below the cortex---Ramalina

54a On mostly dry rock faces on land; thallus not gelatinous, white or grey; common species on granite---Peltula
54b On temporarily submersed rocks in streams; thallus gelatinous, black; rare species---55

55a Lobes flat, little branched, over 1 cm long---Jenmania
55b Lobes rounded and richly branched, forming cushions less than 1 cm thick---Ephebe

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page editor: Harrie Sipman, this page last updated 14 June 2005, imprint
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