Bryological and Lichenological Section/ABLS
Egan, Robert S. , Harms, Robert , Widhelm, Todd .
Studies on the Lichen Parmotrema rigidum from North and South America.
In 1914 Brent Lynge described Parmelia rigida (Parmotrema rigidum) based on a collection from Rio Grande do Sul in southeastern Brazil. Later, Mason Hale, William Culberson and others reported that this member of the Parmotrema perforatum group also occurred in coastal regions of the southeastern United States from Texas north to Delaware and was represented by two chemical populations, one with atranorin and alectoronic acid (K-) and another containing atranorin, alectoronic and norstictic acids (K+). During our investigations of these two chemical populations from the southeastern United States, we also examined specimens identified as P. rigidum from Brazil, Uruguay, and Paraguay, all collections lacking norstictic acid (K-). Average spore width and length from North American specimens were significantly different than measurements from South American collections. In many cases, spores from South American specimens (18-33 x 9-19 µm; mean length 22.3 µm, mean width 12.5 µm) are twice the size of the North American collections (9-15 x 5-9 µm; mean length 12.6 µm, mean width 6.5 µm). Conidia from South American specimens ranged from 7-16 µm (mean 10.6 µm), while the North American specimens measured 11-20 µm (mean 15.7 µm). Marginal cilia on South American collections are longer (mean 2.7 mm) than on specimens collected in North America (mean 1.3 mm). These differences in morphology and geography strongly suggest the South American and North American populations represent two distinct species. If measurements of the type specimen of Parmelia rigida Lynge correspond to these other South American collections, a new name will be needed for the alectoronic acid (K-) population common in the southeastern United States. The taxonomic status of the alectoronic and norstictic acid-containing population (K+) in North America is still under study.
1 - University of Nebraska at Omaha, Biology, 60th & Dodge Street, Omaha, Nebraska, 68182-0040, USA
Presentation Type: Poster
Location: Special Event Center (Cliff Lodge)
Date: Tuesday, August 3rd, 2004
Time: 12:30 PM