Immersaria Aegaea, A Puzzling New Lichen Species from the Mediterranean

Immersaria athroocarpa is a widespread species in Europe and elsewhere. However, samples from the Aegean Sea islands (Greece) deviate phylogenetically and are described here as a separate, cryptic species, which lacks clear morphological characters, I. aegaea . It has also been found in Syria and is possibly widespread in the Mediterranean. Despite its cryptic nature, I. aegaea forms in ITS trees a well-supported, basal clade in Immersaria , with 22 differentiating positions. In this way it differs conspicuously from the recently described species of Immersaria from China, which are morphologically distinct and have few differentiating positions in the ITS sequence. A similar situation with strong phylogenetic and slight morphological differences is known for Aspiciliella portosantana . Possibly these differences are connected with populations that became trapped in insular habitats and turned into endemic taxa when the rest of the species evolved further.