Public Description of Rhizocarpon geographicum group

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Name: Rhizocarpon geographicum group
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Description status: Unreviewed
 (Latest review: 2015-03-24 11:54:28 CDT (-0400) by jason)

Taxonomic Classification:

Domain: Eukarya
Kingdom: Fungi
Phylum: Ascomycota
Class: Lecanoromycetes
Family: Rhizocarpaceae

General Description:

This is a synopsis of the yellow species of Rhizocarpon, often referred to simply as R. geographicum group sensu lato. But note that there are actually four separate groups of yellow species. It is probably unknown whether these groups are of taxonomic value, but they are definitely useful for identification purposes. This information was compiled from several sources (see below).

R. geographicum group – spores muriform, medulla I+ violet, epihymenium “indinstinct” (subtle character, compare with viridiatrum group)
a) R. geographicum – spores 20-35µm, K- P+o, hymenium clear; widespread
b) R. macrosporum – spores 30-60µm, K- P+o, hymenium ~greenish; widespread
c) R. riparium – spores 25-40µm, usually K+, hymenium ~greenish; widespread
d) R. lecanorinum – areoles crescent-shaped, surrounding apothecia; K+y; widespread
e) R. ferax – like lecanorinum but K- P+o; only known from Ireland?
f) R. saanaense – like macrosporum but larger areoles; arctic-alpine
g) R. carpaticum, R. intermediellum, R. atroflavescens – spores submuriform; arctic-alpine
h) R. tinei, R. lindsayanum, R. tavaresii, R. sublucidum, R. sphaerosporum – apparently synonymized away(?)
i) R. ridescens – sorediate(!); Romania

R. viridiatrum group – spores muriform, medulla I-, epihymenium dark
a) R. viridiatrum – initially parasitic; widespread
b) R. lusitanicum – initially parasitic; endemic to Portugal
c) R. subtile – initially parasitic; endemic to Greenland
d) R. oportense – 8 spores per ascus; endemic to your area
e) R. cookeanum – 2 spores per ascus; endemic to northwestern USA
f) R. tetrasporum – 4 spores per ascus; southern Europe

R. alpicola group – spores 1-septate, > 18µm, epihymenium indistinct
a) R. alpicola – “highest mountains of Europe”
b) R. atroalbescens – arctic
c) R. inarense – arctic
d) R. eupetraeoides – arctic

R. superficiale group – spores 1-septate, < 18µm, epihymenium dark
a) R. superficiale – widespread
b) R. parvum – arctic
c) R. dispersum – Spitzbergen
d) R. pusillum – parasitic on Sporostatia, alpine
e) R. effiguratum – parasitic on Pleopsidium
f) R. norvegicum – parasitic on Tremolecia; arctic-alpine


Runemark, H. 1956. Studies in Rhizocarpon I. Taxonomy of the yellow species in Europe. Opera Botanica 2:1.

Feuerer, T. & E. Timdal. 2004. Rhizocarpon. In: Nash, T.H, III, B.D. Ryan, P. Diederich, C. Gries and F. Bungartz (eds.). Lichen Flora of the Greater Sonoran Desert Region, Vol. 2. Lichens Unlimited, Arizona State University, Tempe, Arizona, pp. 456-466.

Fletcher, A., O.L. Gilbert, S. Clayden & A.M. Fryday. 2009. Rhizocarpon. In: Smith, C.W., A. Aptroot, B.J. Coppins, A. Fletcher, O.L. Gilbert, P.W. James and P.A. Wolseley (eds.). The Lichens of Great Britain and Ireland. The British Lichen Society.

Ryan, B. Unpublished keys. Last revised: May 1994.

Description author: Jason Hollinger (Request Authorship Credit)

Created: 2015-03-24 11:53:41 CDT (-0400) by Jason Hollinger (jason)
Last modified: 2015-03-24 11:54:28 CDT (-0400) by Jason Hollinger (jason)
Viewed: 21 times, last viewed: 2017-05-05 06:54:55 CDT (-0400)