In Eastern North America, we found that the species so long confused with Punctelia subrudecta actually seemed to be an undescribed species, which we named after my undergraduate advisor (Dr. Martha Case of the College of William & Mary):
Punctelia jeckeri. (Lendemer 14695, NY). A & B, pruinose lobe tips with arrows highlighting position of the pruina, ×5; C, geographic distribution based on selected herbarium material at NY, shaded regions correspond to western populations mapped by Brodo et al. (2001); note that several populations in Canada are not mapped due to space constraints; D, thallus margin, ×0.5; E, soralia, ×1.
Even though the ITS sequences match up perfectly with European material, we refer to the western North American material as Punctelia jeckeri s. lat., since the conidia do not exactly match P. jeckeri as formally defined. However, we put forth the hypothesis that there may actually be two species in Europe with pruinose lobe tips, but different conidia. This hypothesis will need to be tested with rigorous sampling from throughout Europe.
The third species that we found in North America represented the 'real' Punctelia perreticulata as originally defined. P. perreticulata is the only species with a distinctly scrobiculate upper surface, and its distribution is centered in the Ozark Ecoregion.
Our paper also provides a key to the genus Punctelia in North America. Anyone who has tried to identify a species in this group should have a look. For those interested in the molecular data or the nitty-gritty of phylogenetic methods, links to the ITS sequences with full GenBank records can be found here and we have also posted the analyzed alignment file (NEXUS).
While there are surely further questions to be answered regarding the genus Punctelia, it is satisfying to have some degree of resolution in this often-misunderstood group of species!
Lendemer, J. C., and B. P. Hodkinson. 2010. A new perspective on Punctelia subrudecta in North America: previously-rejected morphological characters corroborate molecular phylogenetic evidence and provide insight into an old problem. Lichenologist 42(4): 405-421.
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