Lectotypification of the threatened endemic Appalachian lichen Alectoria fallacina

Alectoria fallacina, described by the prolific 20th century lichenologist Josef Motyka, is a threatened species narrowly endemic to the Appalachian Mountains of eastern North America. The production of a unique unidentified fatty acid as the main secondary metabolite chemically separates A. fallacina from its congeners, especially the morphologically similar A. sarmentosa. Here we show that while A. fallacina and A. sarmentosa are entirely allopatric, the type collection of A. fallacina is a mixture of the two taxa and the holotype is A. sarmentosa. Detailed analyses of the original material support the conclusion that the lichen in the holotype packet was taken from another collection, and is in direct conflict with both the protologue and the current application of the name. We assert that the lichen currently assumed to be the holotype of A. fallacina was erroneously placed in the holotype packet by Motyka after the description, while the actual holotype lichen was likely retained in his personal herbarium now deposited at LBL. This highly unusual scenario is supported by other cases from the literature pertaining to the types of names published by this author. Based on the fact that the currently accepted holotype of A. fallacina directly conflicts with the protologue, that all evidence suggests it could not have been derived from the type locality, and the known working methods of both the collector of the type (Gunnar Degelius) as well as the describing author (Motyka), the holotype of A. fallacina is treated as effectively lost and the name is lectotypified with an isotype that unambiguously represents A. fallacina.

Automated summary

Alectoria fallacina, a threatened lichen species, is found in the Appalachian Mountains of eastern North America. However, the type collection of A. fallacina is a mixture of two taxa and the holotype is actually A. sarmentosa. Detailed analysis suggests that the holotype lichen was mistakenly placed in the type collection, while the actual holotype may be retained in the collector's personal herbarium. This unusual scenario is supported by similar cases from literature. Accordingly, the holotype of A. fallacina is considered lost, and a new lectotype is designated to represent the species.