Preliminary key to Lecanora species likely to occur in New England

H. Thorsten Lumbsch and Irwin M. Brodo

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 This is a very first attempt to key out Lecanora species likely to occur in New England. The key is thought as an addition to the keys available for North America and the special keys for certain groups, such as the key by Brodo (1984) and cannot replace them. Comments and suggestions are welcome; they may be sent to the first author at lumbsch@uni-essen.de

1a - Thallus placodioid, effigurate to almost foliose .......................................................................... 2
1b - Thallus crustose, not effigurate or almost foliose ........................................................................ 6

2a - Thallus grayish white to yellowish brown, lacking usnic acid, containing xanthones,
        strictly maritime ....................................................................................................................... 3
2b - Thallus greenish to yellowish, containing usnic acid, not especially maritime ......................... 4

3a - Thallus consisting of scattered lobate areoles, not rosette-forming; infrequent ..........
        ...................................................................................................................... L. contractula Nyl.
3b - Thallus forming rosettes, with very narrow, parallel, peripheral lobes; known only from
        the type ......................................................................................................... L. microbola Lamb

4a - Apothecial discs pruinose, pale or brown, rare ............................................... L. weberi Ryan
4b - Apothecial discs epruinose, greenish or orange-yellow ......................................................... 5

5a - Thallus with narrow lobes, often paler or blackish at the edges; containing zeorin, lacking
        placodiolic acid ................................................................ L. muralis (Schreb.) Norman
5b - Thallus with dispersed, loosely attached, lobate areoles, uniform in color, often resembling
        a Rhizoplaca species, lacking zeorin, containing placodiolic acid ........ L. opiniconensis Brodo

6a - Thallus growing on siliceous rocks ........................................................................................ 7
6b - Thallus growing on other substrates ...................................................................................... 23

7a - Thallus sorediate ................................................................................................................... 8
7b - Thallus not sorediate ............................................................................................................. 9

8a - Thallus gray (lacking usnic acid), with discrete soralia, lacking a prothallus;
         rare ........................................................................................................... L. umbrosa Degel.
8b - Thallus yellowish green (containing usnic acid), leprose, with a white fibrous
         prothallus; common ..................................................................... L. thysanophora R.C. Harris

9a - Thallus K + yellow, containing atranorin, whitish, grayish, or yellowish green ................... 10
9b - Thallus K -, lacking atranorin, whitish or yellowish-green to green ..................................... 19

10a - Apothecial discs heavily pruinose, C + orange, containing chromones ............................. 11
10b - Apothecial discs epruinose or slightly pruinose ................................................................ 12

11a - Apothecia constricted at base to slightly stalked, discs bluish pruinose, with parathecial
          crown .................................................................................................... L. bicincta Ramond
11b - Apothecia sessile to immersed, discs whitish or grayish pruinose, lacking parathecial
          crown ................................................................................................ L. rupicola (L.) Zahlbr.

12a - Apothecia aspicilioid or biatorine (not lecanorine), black; epihymenium blue-green,
          HNO3+ deep red ........................................................................................................ 13
12b - Apothecia lecanorine, brown to almost black; epihymenium reddish brown (HNO3-)
          to olive (HNO3+ pinkish) .....................................................................,,................... 14

13a- Apothecia biatorine, thallus containing usnic acid; alpine ................................
        ....................................................................... L. marginata (Schaerer) Hertel & Rambold
13b - Apothecia aspicilioid, thallus lacking usnic acid; low elevations ...................
        .......................................................................... L. oreinoides (Körber) Hertel & Rambold

14a - Amphithecium containing small crystals; strictly maritime ................ L. xylophila Hue
14b - Amphithecium containing large crystals; mostly not maritime ...................................... 15

15a - Epihymenium red-brown to olive, with abundant crystals (POL+), crystals in epipsamma
         and pigmentation dissolving in KOH ............................................................. L. cenisia Ach.
15b - Epihymenium red-brown or dark brown to blackish, lacking crystals (POL-) or with very
         few crystals, pigmentation remaining in KOH or changing color ....................................... 16

16a - Apothecial discs dark brown to blackish, epihymenium often changing to greenish in KOH,
          with few crystals on surface ........... L. argentea Oxner & Volkova (syn. L. fuliginosa Brodo)
16b - Apothecial discs red-brown to dark brown, epihymenium red-brown, lacking crystals,
          not altered in KOH ............................................................................................................. 17

17a - Thallus continuous to rimose-areolate, containing zeorin ................. L. subimmergens Vain.
17b - Thallus granular-verrucose or dispersed areolate, not continuous to rimose ...................... 18

18a - Thallus dispersed areolate, spores 5.5-7 µm wide, containing 2'-O-methylperlatolic acid,
           lacking zeorin ........................................................................................... L. pseudistera Nyl.
18b - Thallus granular-verrucose, spores 7-9 µm wide, lacking 2'-O-methylperlatolic acid,
           containing zeorin ...................................................................................... L. perplexa Brodo

19a - Thallus whitish to grayish, C+ orange, containing xanthones, lacking usnic acid and zeorin,
        apothecia red-brown; maritime .................................................................... L. contractula Nyl.
19b - Thallus yellowish to greenish, C-, lacking xanthones, containing usnic acid and zeorin,
          apothecia yellowish green, yellowish brown or greenish brown, not red-brown; not
          maritime .............................................................................................................................. 20

20a - Thallus thick, with convex areoles; apothecial discs pale to dark yellowish brown,
          epruinose, usually with a conspicuous parathecial crown (inner ring)....L.chlorophaeodes Nyl.
              (The placodioid L. weberi ,with pruinose discs, is similar; see 4a)
20b - Thallus thick, thin, or endolithic; areoles, if present, not thick and convex; apothecial discs
          yellowish brown to greenish brown, lacking a conspicuous parathecial crown ................... 21

21a - Apothecia immersed in thallus, apothecial disc greenish brown ; thallus well-developed,
        continuous to areolate ............................................................................. L. intricata (Ach.) Ach.
21b - Apothecia sessile, apothecial disc yellowish-green .............................................................. 22

22a - Ascospores broadly ellipsoid to ellipsoid, 5-6 µm wide, apothecia lecanorine; thallus scanty,
          dispersed areolate to entirely endolithic; common .................... L. polytropa (Hoffm.) Rabenh.
22b - Ascospores narrowly ellpsoid, 3-4 µm wide, apothecia biatorine; thallus dispersed to
          continuous areolate; rare ............................................................ L. ochraceorubescens Arnold

23a - On calciferous rocks ............................................................................................................... 24
23b - On bark, soil or mosses .......................................................................................................... 26

24a - Thallus whitish, well developed .................... L. albescens (Hoffm.) Branth & Rostrup
24b - Thallus thin, almost invisible or reduced to small parts surrounding apothecia ...................... 25

25a - Apothecial margins thick, crenulate, often discontinuous ........................... L. crenulata Hook.
25b - Apothecial margin thin or thick, not crenulate or discontinuous ..........................................
             ......................................................................................... L. dispersa (Pers. ) Sommerf. s. lat.

26a - On soil or mosses ................................................................................................................... 27
26b - On bark or wood .................................................................................................................... 28

27a - Apothecial margin K- (lacking atranorin); amphithecium lacking crystals, [containing
          5,7-dichlorolichexanthone or lacking secondary metabolites] ................ L. hagenii (Ach.) Ach.
27b - Apothecial margin K+ yellow (containing atranorin); amphithecium with small
         crystals ................................................................................................. L. epibryon (Ach.) Ach.

28a - Thallus or apothecial margins yellowish to greenish, containing usnic or isousnic acids ......  29
28b - Thallus or apothecial margins whitish, grayish or brownish, lacking usnic acid ................... 39

29a - Thallus or apothecial margins sorediate ................................................................................. 30
29b - Thallus and apothecial margins esorediate ............................................................................. 34

30a - Thallus thin, with conspicuous, white, fibrous prothallus ...... L. thysanophora R.C. Harris ined.
30b - Thallus thin or thick, prothallus not visible or inconspicuous ................................................ 31

31a - Thallus esorediate, apothecial margins granular-sorediate ........ L. strobilina (Sprengel) Kieffer
31b - Thallus and apothecial margins sorediate ............................................................................... 32

32a - Thallus C-, P+ orange-red, containing fumarprotocetraric acid, soralia greenish-gray .......
           ........................................................................................... L. conizaeoides Nyl. ex Crombie
32b - Thallus C+ orange, P-, containing xanthones ......................................................................... 33

33a - Soralia bluish gray, well delimited, on wood near seashores ............ L. orae-frigidae R. Sant.
33b - Soralia yellowish green, soon covering whole thallus, on wood or bark near
          seashores ....................................................................................................... L. expallens Ach.

34a - Apothecial margins biatorine, soon becoming excluded ......................................................... 35
34b - Apothecial margins biatorine or lecanorine, persistent .......................................................... 36

35a - Ascospores 9-16 x 4-5.5 µm, apothecial discs bright yellow, pale yellow-green or
          yellow-brown, thallus thin or verruculose, yellowish gray or whitish, epiphloeodal ..........
                 .................................................. L. symmicta (Ach.) Ach. s.lat. (syn. L. symmictera Nyl.)
35b - Ascospores 5.5-10 (-12) x 2.5-4.5 (-5) µm, apothecial discs waxy yellow-brown to
          yellow-green or olive-brown to brownish black, thallus inconspicuous, greenish or
          yellowish-green, usually endophloeodal ..................................... L. subintricata (Nyl.) Th. Fr.

36a - Apothecia biatorine .......................................................................... L. symmicta (Ach.) Ach.
36b - Apothecia lecanorine ............................................................................................................ 37

37a - Apothecial discs with a bright yellow pruina, margins thick, crenulate; contains usnic
          acid .............................................................................................................. L. cupressi Tuck.
37b - Apothecial discs greenish, gray- or pink-brown or yellowish, without yellow pruina; margins
          thin; contains isousnic acid .................................................................................................. 38

38a - Apothecial margin smooth, level with the disk; spores narrowly ellipsoid, 7-14 x3-4.1 µm
           .............................................................................................................. L. piniperda Körber
38b - Apothecial margin thalline in texture, usually prominent; spores ellipsoid to broadlyellipsoid,
         7-13 x 4-7 µm ............................................................................... L. saligna (Schrader) Zahlbr.

39a - Thallus K+ distinctly yellow, containing atranorin .............................................................. 40
39b - Thallus K-, lacking atranorin ............................................................................................... 59

40a - Apothecial discs heavily whitish pruinose; apothecial sections P+ red-orange .........,......... 41
40b - Apothecial discs epruinose or slightly pruinose; apothecial sections P- or PD+ red ........... 43

41a - Apothecia 0.3-1.5 mm in diam., apothecial margins thin, pseudocortex 35-75 µm thick;
          contains protocetraric acid .................................................................... L. albella (Pers.) Ach.
41b - Apothecia 0.8-3.0 mm in diam., apothecial margins thick, pseudocortex 45-105 µm thick;
          contains virensic or protocetraric acid ........... "L. caesiorubella" Ach.:  .......................... 42

42a - Apothecial disks C+ yellow, margin (in section) K+ red (norstictic acid); contains
          protocetraric acid; coastal plain ................................. subsp. prolifera (Fink) R.C. Harris
42b - Apothecial disks C-, margin (in section) K+ yellow (lacking norstictic acid); contains
          virensic acid; boreal-montane ............................................................ subsp. caesiorubella

43a - Thallus sorediate .................................................................................................................. 44
43b - Thallus esorediate ................................................................................................................ 45

44a - Amphithecium with large crystals, thallus dark grayish yellow, on wood;
          rare ............................................................................................................. L. farinaria Borrer
44b - Amphithecium with small crystals, thallus whitish, on bark; common ........ L. impudens Degel.

45a - Amphithecium with small crystals, epihymenium egranulose ............................................... 46
45b - Amphithecium with large crystals, epihymenium granulose or egranulose ........................... 49

46a - Amphithecial cortex absent or indistinct .................................................. L. imshaugii Brodo
46b - Amphithecial cortex present, gelatinous ............................................................................... 47

47a - Amphithecial cortex distinctly delimited, small crystals confined to medulla, on driftwood
          at seashore ........................................................ L. xylophila Hue (syn. L. grantii H. Magn.)
47b - Amphithecial cortex indistinctly delimited, small crystals in medulla extending into cortex,
          usually on bark .................................................................................................................... 48

48a - Apothecia large, (0.5-)0.7-2.0(-3.0) mm in diameter, constricted at base, ascospores
          13-18 x 7-11 µm .......................................................................................L. allophana Nyl.
48b - Apothecia small, 0.3-.6(-1.2) mm in diameter, adnate, ascospores 9-13 x 6-8 µm .........
            ............................................................................................... L. glabrata (Ach.) Malme

49a - Epihymenium egranulose, pigmentation not dissolving in KOH, but sometimes
          altering color ...................................................................................................................... 50
49b - Epihymenium granulose, crystals and pigmentation dissolving in KOH .............................. 51

50a - Amphithecial cortex distinct, thallus verrucose to continuous, contains gangaleoidin,
          lacks zeorin .............................................L. argentata (Ach.) Malme [includes L. subrugosa]
50b - Amphithecial cortex thin, indistinct, thallus granulose-verrucose, lacks gangaleoidin,
          contains zeorin .............................................................................. L. perplexa Brodo

51a - Epihymenium inspersed with fine granules, granules insoluble in HNO3  ............................ 52
51b - Epihymenium with coarse granules at surface, granules soluble in HNO3 ........................... 54

52a - Amphithecial cortex basally expanded, ascospores 12-18 x 8-11 µm, apothecial disc usually
          pitch black to dark brown ................................................... L. circumborealis Brodo & Vitik.
52b - Amphithecial cortex uniform or expanded, ascospores 10-14 x 6-9 µm, apothecial disc
          variable, pale to dark brown, rarely black .............................................................................. 53

53a - Usually on conifers, lignum, willows or elder, apothecial disc dark brown to red-brown,
          margin thin, amphithecial cortex thicker (2-3x) at base, thallus mostly P+ red, rarely all or
          partly P- ............................................................................................ L. pulicaris (Pers.) Ach.
53b - On deciduous trees, apothecial disc orange-brown to red-brown, margin thick, amphithecial
          cortex relatively uniform in thickness, thallus P-, very common .... L. hybocarpa (Tuck.) Brodo

54a - Amphithecial cortex very thin and inconspicuous up to 15 µm thick, epihymenium P+ orange,
          apothecia semi-immersed, at least when young .................................. L. cinereofusca H. Magn.
54b - Amphithecial cortex more than 15 µm thick, gelatinous, epihymenium P-, apothecia sessile .... 55

55a - Apothecial disks C+ orange (xanthone), dull or lightly pruinose, margins thin;coastal plain
          (Long Island, NY) ................................................................................... L. louisianae de Lesd.
55b - Apothecial disks C-, pruinose or not; margins thick or thin; common ..................................... 56

56a - Apothecia appressed, flat, broad (up to 3 mm in diam.), margins thin, discs epruinose .........
            ..................................................................................................... L. wisconsinensis H. Magn.
56b Apothecia not appressed, small or broad, margins relatively thick, discs slightly pruinose
          or epruinose ....................................................................................................................... 57

57a - Apothecial discs dark brown to brown-black, on lignum ................................... L. cenisia Ach.
57b - Apothecial discs orange-brown to red-brown, on bark ........................................................... 58

58a - Apothecial margins smooth to slightly verrucose, thallus smooth to verruculose .........
                .......................................................................................................... L. chlarotera Nyl.
58b - Apothecial margins verrucose, thallus coarsely verrucose to granulose ........ L. rugosella Zahlbr.

59a - Asci 12-32-spored ................................................................................. L. sambuci (Pers.) Nyl.
59b - Asci 8-spored ........................................................................................................................ 60

60a - Epihymenium not granular; ascospores 10-15 x 3.5-5.3 µm ............... L. hypoptoides (Nyl.) Nyl.
60b - Epihymenium granular ............................................................................................................ 61

61a - Ascospores 6-8 x (2-) 3-3.5 (-4.5) µm, on wood, pine bark and cones ..............L. minutella Nyl.
                  (syn. L. fuscidula Degel.)
61b - Ascospores generally longer than 7 µm ................................................................................... 62

62a - Apothecial margin soon disappearing; amphithecial medulla containing few algaeconfined
          to base; ascopores ellipsoid, 6.5-10 (-12) x 3.5-5 µm ................ L. subintricata (Nyl.) Th. Fr.
62b - Apothecial margin persistent; amphithecial medulla containing abundant algae; ascospores
         (7-) 8-16 µm long ................................................................................................................. 63

63a - Apothecial margin level with disk, colored like the disk or paler, smooth; cortex usually
          indistinct or absent; ascospores narrowly ellipsoid to cylindrical, 2.5-4.1 µm wide ..........
            ......................................................................................L. piniperda Körber (var. nigrescens)
63b - Apothecial margin usually prominent, thalline in color and texture, clearly lecanorine;
          cortex well developed, gelatinous; ascospores ellipsoid, (3-) 4-7 µm wide .................
            ................................................................................................ L. hagenii (Ach.) Ach. complex
 

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About this webpage:

Written by: H Thorsten Lumbsch and Irwin M. Brodo
Edited for the internet by: Philip F. May
Original date online:  16 May 2000

Comments on content to: lumbsch@uni-essen.de
Comments HTML and web-related matters: pfmay@aol.com

Suggested citation: Lumbsch, H.T. and Brodo, I.M. 2000.  Preliminary key to Lecanora species likely to occur in New England [online].  Farlow Herbarium, Harvard University, Cambridge, Massachusetts.  Available:  http://herbaria.harvard.edu/Data/Farlow/lichens/Lecanora_New_England.html