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Parmotrema arnoldii (Du Rietz) Hale
Arnold's Powdered-ruffle
Federal Protection: No US federal protection
State Protection: No Georgia state protection
Global Rank: G3G5
State Rank: SNR
Element Locations Tracked in Biotics: No
SWAP 2015 Species of Greatest Conservation Need (SGCN): No
SWAP 2025 Species of Greatest Conservation Need (SGCN): No
2025 SGCN Priority Tier: None
Element Occurrences (EOs) in Georgia: 0
Habitat Summary for element in Georgia: Montane forests
Pale green-gray thallus of broad (1-1.5 cm wide) lobes with undersides brown at lobe edges, black in center, rhizines absent in broad zone at edges; old lobes edged with even mounded gray-green soralia; lobes with abundant, long black cilia; CHEMISTRY: medulla K-, C-, KC+ pink, PD-, UV+ blue-white (alectoronic acid); FIELD ID: in northern-tier counties, other big Parmotrema with lumpy marginal soralia & bare brown undersides to lobe tips are P. perlatum, P. margaritatum, & P. diffractaicum, sorted with K & UV tests
Also large are P. perlatum with UV-, K+ yellow, PD+ orange medulla & P. diffractaicum with CK+ orange, UV+ yellow medulla; Parmotrema reticulatum is smaller, has cracked lobe surfaces, undersides with rhizines up to edges & different chemistry; P. louisianae has identical chemistry but is also smaller & has white undersides to lobe tips; also consider rare P. stuppeum, with more even, linear soralia K+ maroon medulla (see key below)
None
Montane forests
Mostly hardwood bark; 1 record on Pinus & 1 on rock
Corticolous foliose lichenized fungus, photobiont a green alga (Trebouxia?)
None
Southern Blue Ridge; disjunct in Piedmont (Stone Mt.)
Unknown
Rare
None
Brodo, I. M. 2001. Lichens of North America. Yale University Press, New Haven, Conn.
Brodo, I. M. 2016. Keys to lichens of North America: revised and expanded. Yale University Press, New Haven, Conn.
Esslinger, T. L. 2021. A cumulative checklist for the lichen-forming, lichenicolous and allied fungi of the continental United States and Canada. Version 24. Opuscula Philolichenum 20: 100-394.
Malcolm Hodges
24 May 2022