Lichen determination keys - neotropical genera -

Key to squamulose lichens

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1a Perithecia present---2
1b Apothecia present, or fruitbodies absent---6

2a Ascospores simple or transversely septate---3
2b Ascospores muriform---4

3a Ascospores simple; no algae present in hymenium---Catapyrenium
3b Ascospores transversely septate; no algae present in hymenium (perithecia rare)---Normandina

4a Algae present in hymenium; cortical cells of thallus smooth-walled---Endocarpon
4b Algae absent in hymenium; cortical cells of thallus finely papilose (in microscopical section)---5

5a Photobiont green---Agonimia
5b Photobiont blue-green---Psoroglaena

6a (1) Squamules rounded, whitish with raised margin, ca. 1 mm diam.; fruit bodies absent (perithecia)---Normandina
6b Squamules usually elongated and greenish, without raised margin---7

7a Algae blue-green---8
7b Algae green---13

8a Thallus gelatinous, without distinct cortex and medulla, with smooth surface---see separate key for Lichinaceae
8b Thallus gelatinous, without distinct cortex and medulla, with papillose hyphae on the upper surface and sorediate below; subfruticose squamules c. 1-2 mm long---Acantholichen
8c Thallus not gelatinous, heteromerous, with distinct cortex and medulla---9

9a Thallus dark brown to black, on sunny rocks---Peltula
9b Like a, on bark---Phyllopeltula
9c Thallus blue-grey to brown, epiphytic, terrestrial or on shady rock---10

10a Thallus with distinct, often tomentose, prothallus; apothecia with or without thalline margin---Parmeliella
10b Thallus without prothallus; apothecia always with thalline margin---11

11a Apothecial margin with green algae; ascospores bicellular, brown---Solorina
11b Apothecial margin with blue-green algae; ascospores simple, hyaline---12
11c Apothecial margin without algae; ascospores simple, hyaline---Coccocarpia

12a Asci with I+ blue apical plug; thallus usually brownish; southward to Mexico?; with white spots on lobe margins---Fuscopannaria
12b Asci without I+ blue apical plug; thallus usually blue-grey; widespread and polymorphic---Pannaria

13a (7) Upper surface of squamules byssoid, lacking cortex---14
13b Upper surface of squamules more or less smooth, with cortex, sometimes pruinose---15

14a Epiphytic; thallus squamules connected into rosette-like thalli, algiferous---Crocynia
14b On algae-covered earth of banks, or on mosses on similar places; "thallus squamules" widely scattered, without algae (basidiocarps)---Cyphellostereum

15a Tomentose prothallus present---16
15b No tomentose prothallus---19

16a Squamules with an upper and lower cortex comprised of a thin layer of cubic cells---Eschatogonia
16b Squamule cortex otherwise, lower cortex usually absent---17

17a Apothecium margin concolorous with thallus, containing algae---Physcidia
17b Apothecium margin not concolorous with thallus, without algae---18

18a Ascospores generally over 25 µm, transversely many-septate---Squamacidia
18b Ascospores generally under 25 µm, simple or one-septate---Phyllopsora

19a (15) Thallus yellow to orange---20
19b Thallus pale grey to greenish grey or somewhat brownish---23

20a Thallus K+ dark violet---21
20b Thallus K- or K+ weakly reddish---22

21a Thallus lobes ascending, c. 2 mm long, convex; medulla yellow; apothecia black, globose---Xanthopsorella
21b Thallus lobes mostly applanate and restricted to thallus margin; medulla white; apothecia shades of yellow to red, usually flat---Caloplaca

22a Apothecia lecanorine, yellow; on rock---Candelina
22b Apothecia lecideine, black; on soil---Psora

23a (19) On soil---24
23b Epiphytic, occasionally on rock---29
23c On rock---37

24a Squamules whitish grey on both sides, elongate and erect; ascocarps unknown---25
24b Squamules more pale on lower side, more or less appressed to substrate; ascocarps often present (when ascocarps absent, see also under dimorphic lichens with squamulose primary thallus, couplet 15)---26

25a Cortical cells of thallus finely papillose; squamules delicate, lacerate---Agonimia
25b Cortical cells of thallus not papillose; squamules thick, crenate---Siphula

26a Ascospores simple---27
26b Ascospores transversely septate; apothecia lecideine---Toninia (s.l.)

27a Apothecia lecanorine---Psoroma
27b Apothecia lecideine---28

28a Thallus without soralia---Psora
28b Thallus with labriform soralia---Trapeliopsis

29a (23) Squamules whitish grey on both sides, erect; ascocarps unknown; on old tree trunks---30
29b Squamules greenish or brownish above, pale below---31

30a Cortical cells of thallus finely papillose; squamules delicate, lacerate---Agonimia
30b Cortical cells of thallus not papillose; squamules thick, crenate---Siphula

31a Squamules very elongated, to c. 15 x 1 mm; ascocarps unknown---Pseudohepatica
31b Squamules rounded to moderately elongate and more or less incised, mostly under 5 mm long---32

32a Thallus thin, corticate with a thin layer of cubic cells on both sides---Eschatogonia
32b Thallus without such cortex---33

33a Ascospores simple---34
33b Ascospores transversely septate---36

34a Thallus C+ red, with labriform soralia---Hypocenomyce
34b Thallus C-, without or with capitate soralia---35

35a Apothecia lecanorine---Psoroma
35b Apothecia biatorine---"Biatora" s.l.

36a Ascospores acicular---Bacidiopsora
36b Ascospores fusiform to bacillar---Psorella

37a (23) Ascospores with many in each ascus, usually under 10 µm long---Acarospora
37b Ascospores 8 in each ascus, usually over 20 µm long---Placopsis

primary / fruticose / foliose / squamulose / foliicolous / crustose / lichinaceae
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© Botanischer Garten und Botanisches Museum Berlin-Dahlem, Freie Universität Berlin
page editor: Harrie Sipman, last update: 14 June 2005, imprint
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