Orvo Vitikainen

Botanical Museum, University of Helsinki, Finland

Orvo.Vitikainen@helsinki.fi

This is a modified version of the key published in Acta Bot. Fennica 152 (1994), with additions of species recognized in Europe since then.

1.    Upper surface tomentose above, at least near lobe end-------------------------- 2

B    Upper surface smooth or scabrous, not tomentose------------------------------ 19

2.    Sorediate, isidiate or phyllidiate------------------------------------------------- 3

B    Soredia and isidia absent (but flattened marginal squamules may be present)-- 6

3.    Sorediate; soralia orbicular and laminal------------------------------------------ 4

B    Isidiate – phyllidiate; soralia absent---------------------------------------------- 5

4.    Apothecia common, marginal rhizines tapered, secondary substances mostly absent          P. didactyla

–     Apothecia rare, rhizines flocculent, soralia mostly KC+ red--------- P. extenuata

5.    Isidia laminal and mainly peltate; lobes usually under 1 cm. broad; apothecia rare P. lepidophora

B    sidia (phyllidia) squamulose or corallinoid, more or less vertical, marginal and laminal; lobes often over 1 cm broad; often fertile------------------------------------------------------ P. praetextata

6.    Photobiont blue-green (Nostoc), blue-grey to brown-green when moist--------- 7

B    Photobiont green alga, thallus bright green when moist; laminal peltate cephalodia containing Nostoc present--------------------------------------------------------------------------------------- 16

7.    Lower surface distinctly veined-------------------------------------------------- 8

B    Lower surface not veined------------------------------------------------------- 15

8.    Rhizines in marginal parts slender, simple or with few branches---------------- 9

B    Rhizines conspicuously and richly branched------------------------------------ 11

9.    Coarse species with often brownish lobes over 1 cm broad; rhizines in central parts of thallus distant, soon darkened; veins brownish and flattened towards thallus centre-------- P. praetextata

B    Small to medium-sized species, lobes usually under 1 cm broad; rhizines and veins otherwise       10

10.  Rhizines long remaining pale; veins raised, long remaining pale---- P. ponojensis

B    Rhizines becoming browned; veins soon flattened, rusty brownish and diffuse in central parts; marginal parts often pruinose and phyllidiateClobulate----------------------------P. monticola

11.  Rhizines confluent; veins soon darkened towards thallus centre or smooth--- 12

B    Rhizines separate; veins conspicuously erect-tomentose also in thallus centre- 14

12.  Coarse species with lobes over 1 cm broad and down-turned lobe ends; veins and rhizines near margins whitish, rhizines stout, bush-like--------------------------------------------- P. canina

B    Small to medium-sized with lobes usually under 1 cm broad; margins upturned; rhizines soon darkened  13

13.  Upper surface with thick grey, mostly appressed tomentum; veins narrow, interstices angular; rhizines squarrosely branched, confluent------------------------------------------- P. rufescens

       (Note: P. virescens, a poorly known taxon with thickish, rigid and somewhat scabrose thallus, not tomentose centrally and with emerald green photobiont, is known from Turkey and might be found in Mediterranean Europe)

–     Upper surface browned, marginal parts with erect tomentum and partly scabrous but becoming glabrescent and glossy towards centre, often with yellow-brown cast; veins in the centre brown to black, coated with dark tomentum; interstices whitish and rounded---------------------------- P. kristinssonii

14.  Lobe margins down-turned; veins raised, narrow (under 1 mm), interstices coarse; rhizines slender, with densely squarrose but short ramifications--------------------------- P. membranacea

–     Lobe margins up-turned or flattened; veins flattened (1C1.5 mm broad); under side in parts ochraceous; interstices pitted; rhizines partly bush-like------------------------------ P. retifoveata

15.  Dense erect tomentum present at margins; bluish or brownish green when wet; under side in the centre soon darkened------------------------------------------------------------------- P. malacea

B    Tomentum erect, sparse; thallus blue-grey when wet, maculate; margins often minutely lacerate; funnel-shaped or flattened green lobelets with dense tomentum often present  Nostoc photosymbiodeme of  P. aphthosaorP. britannica

16.  Lower surface not or only diffusely veined; rhizines diffuse, short; under side of apothecia with a continuous green cortex, cephalodia flat to convex or peltate---------------------- 17

B    Lower surface with a distinct network of pale or darkened veins; rhizines separate, fasciculate; under side of apothecia with discontinuous cortex, cephalodia convex to cerebriform----------- 18

17.  Cephalodia adnate to sessile, flattened to convex-------------------- P. aphthosa

B    Cephalodia peltate, lobulate----------------------------------------- P. britannica

18.  Upper surface with erect tomentum at margins, centrally glabrose, under surface with darkening raised veins------------------------------------------------------------------------- P. leucophlebia

–     Uppers surface with erect or arachnoid tomentum also centrally, under surface with reticulate depressions------------------------------------------------------------------------------ P. latiloba

19.  With marginal linear soralia--------------------------------------------- P. collina

B    Thallus without soralia---------------------------------------------------------- 20

20.  Upper surface distinctly scabrous, matt---------------------------------------- 21

B    Upper surface smooth, usually glossy------------------------------------------- 23

21.  Lower surface distinctly veined------------------------------------------------ 22

B    Lower surface without veins; rhizines short, thick, fasciculate---------- P. lyngei

22.  Rhizines fasciculate or fibrillose, soon blackened; lower side dark in the centre P.scabrosa

B    Rhizines pale, simple or in loose bundles; lower side pale in the centre P. scabrosella

23.  Lower surface with dark fan-shaped veins and globular cephalodia attached to them; only one rhizine; photobiont green------------------------------------------------------------- P. venosa

B     Lower surface with numerous rhizines and a reticulate veining pattern or veins lacking; photobiont blue-green(Nostoc)------------------------------------------------------------------------------------- 24

24.  Veins white and raised, at least near thallus margin; rhizines pale, simple; devoid of lichen substances     P. degenii

B    Veins flattened or lacking; rhizines fasciculate, darkened; lichen substances present          25

25.  Lower surface lacking veins, dark with small whitish spots; marginal and laminal schizidia present; apothecia rare, with flat discs------------------------------------------- P. elisabethae

B    Lower surface with various veining

patterns; upper part of medulla not scaling off as schizidia------------------------- 26

26   Veins mostly under 1.5 mm broad, flattened----------------------------------- 27

B    Veins usually over 2 mm broad, elevated--------------------------------------- 28

27.  Rhizines separate, fasciculate, soon blackening, arranged in concentric lines; apothecia with flat discs; marginal parts of lower surface whitish---------------------------------P. horizontalis

B    Rhizines confluent or diffuse when young, not arranged in concentric lines; marginal parts of lower surface with a brownish hue; margins often dilacerate and lobulate; apothecia with brown saddle-shaped discs          P. polydactylon

28.  Veins flattened or diffuse, reticulate; rhizines separate------------------------ 30

B    Veins raised, not markedly reticulate, rhizines diffuse; margins often pruinose 29

29.  Upper surface usually slate blue, sometimes with brownish cast; lobes under 1.5 cm broad; venation reticulate, becoming blackened; rhizines diffuse, blackened; apothecia common, dark, tubular; phlebic acids absent------------------------------------------------------------------------ P. neckeri

B    Veins fan-shaped, pale or brownish; rhizines confluent or short, not markedly blackened; upper surface maculate; margins often inrolled; no apothecia in European material; containing phlebic acids A and B          P. frippii

30.  Upper surface glossy; venation reticulate, veins somewhat raised, darkening towards thallus centre; rhizines darkening, stout, fasciculate, often over 5 mm long-------------------------------- 31

–     Upper surface mat, often maculate; rhizines rather thin, usually under 5 mm long  32

31.  Thallus mostly greyish blue, undulate, rhizines slender, ropy-- P. neopolydactyla

–     Thallus often emerald green when moist, mostly even, rhizines bushy branched P. occidentalis

32.  Lobes 0.5C1 cm, thin, delicate, commonly lobulate or incised, grey; Azores P. dissecta

B    Lobes commonly to 1 cm broad and mainly entire, often with brownish cast- 33

33.  Lower surface with mainly ochraceous and diffuse venation; rhizines rather thin, pale; western and southern Europe-------------------------------------------------------------------- P. hymenina

B    Lower surface with narrow, flat, soon dark brown or blackish veins; rhizines slender, soon    darkening; Azores, Iberian peninsula ---------------------------------------------------------- P. melanorrhiza

 Suggested Citation:

Vitikainen O. 2010: A key to the European species of Peltigera Willd.- In: Sohrabi, M. (ed.): Myco-Lich: Online Mycology-Lichenology of Iran, http://www.myco-lich.com/ Retrieved  XX, XX 2010.

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Page Editor: Mohammad Sohrabi