Notes on Lichens: difference b/t Xanthoria and Caloplaca

To refresh my memory (and get some updates)

So basically, Xanthoria have a lower cortex and thus are considered foliose; Caloplaca lack lower cortex and are considered crustose. However, both can be lobed, especially at margins, so this is tricky. "Deeper orange" in note below, is bordering on red at times.

Even worse, looks like new genera have been created in both Xanthoria and Caloplaca (see Polycaulionia, Xanthocarpa, Calogaya). Good grief.

  1. See Sharnoff photos for reference: (Caloplaca updates) and (Xanthoria updates)
  2. From CNALH:

"Notes: The thallus morphology of this species is most similar to X. sorediata, but X. elegans never produces soredia. Xanthoria elegans could also be confused with some taxa in Caloplaca, such as C. saxicola and C. trachyphylla. They share several characters, such as ellipsoid conidia and being apotheciate and non-sorediate. Xanthoria elegans, however, always have a lower cortex, where occasional hapters that attaches the thallus to the substrate are found. Rarely, X. elegans has been confused with X. parietina, as they both are apotheciate and have large thalli diameters compared to other taxa in Xanthoria. They differ by the morphology of the lobes, however, with X. elegans having narrower lobes that are convex and more tightly adnate, and lack the marginal border of X. parietina. In addition, the upper cortex of X. elegans is usually deeper orange pigmented. "

  1. Rusavskia elegans (Link) S. Y. Kondr. & Kärnefelt is new name, redirected from: Xanthoria elegans (Link) Th. Fr.)
  2. Gets worse yet: (Am J Bot. 2003 Jul;90(7):1095-103. doi: 10.3732/ajb.90.7.1095. Phylogenetic study of Fulgensia and allied Caloplaca and Xanthoria species (Teloschistaceae...)
    "The traditional generic-level classification schemes for the family Teloschistaceae appear to be highly artificial. All three genera [Fulgensia, Xanthoria, and Caloplaca] were found to be nonmonophyletic."

Posted on December 01, 2018 04:54 PM by slwhiteco slwhiteco


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