@ARTICLE{TreeBASE2Ref16238, author = {Scott LaGreca}, title = {A phylogenetic evaluation of the Ramalina americana chemotype complex (Ramalinaceae) based on rDNA ITS sequence data.}, year = {1999}, keywords = {}, doi = {}, url = {http://www.jstor.org/stable/3244250}, pmid = {}, journal = {The Bryologist}, volume = {102}, number = {4}, pages = {602--618}, abstract = {The nature and significance of morphologically indistinguishable chemical races has been an active area of lichenological research for decades. This study uses a phylogenetic analysis of rDNA sequences to investigate whether the morphologically indistinguishable chemotypes of Ramalina americana are distinct species. Cladistic analysis of ITS sequences from 19 R. americana individuals (representing eight of the nine described chemotypes) and four outgroup Ramalina species reveals that R. americana comprises at least two cryptic, phylogenetic species. One, R. americana sensu stricto, is largely acid-deficient and grows in the northern half of the range of the complex (and at high elevations in the Southern Appalachian Mountains); the other, R. culbersoniorum sp. nov., encompasses most of the chemical diversity and occurs in the southern half of the range. Kimura 2-parameter genetic-distance estimates indicate that these two species are as different from each other as each is from outgroup Ramalina species. There is no meaningful resolution within either species. Among the outgroup Ramalina species, R. intermedia appears to be sister to the northern species, while R. fastigiata, the presumed sister group to the complex, forms an unresolved trichotomy with both the northern and southern species. R. sinensis, often assumed to be closely related to the complex, is only distantly related. The results of this study agree with previous studies of other lichens in that each chemotype does not represent a distinct species, nor are they all conspecific. Rather, the complex can be divided into two species, each consisting of multiple chemical races.} }

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