The Pseudocyphellaria hookeri clade (Peltigerales): a species pair-photosymbiodeme speciation complex?

Le résumé fourni par la source

We present an integrative taxonomic revision of the Pseudocyphellaria hookeri group in Aotearoa | New Zealand. Molecular data of the fungal ITS barcoding marker resolve the group as monophyletic, in a strongly supported clade on a long stem branch, related to the P. crocata group. Our study confirms the three species previously assigned to this group, P. hookeri, P. durietzii, and P. montagnei, as part of this clade. In addition, a fourth species was detected and is formally described here, namely P. coralloidea sp. nov. It is characterized by a cyanobacterial photobiont and coralloid clusters of stout, robust isidia partially eroding into soralia-like structures. Given that the P. hookeri clade contains four different combinations of photobionts and reproductive structures (durietzii: green, apothecia; montagnei: green, phyllidia; hookeri: cyanobacterial, apothecia; coralloidea: cyanobacterial: isidia), we hypothesized that this clade evolved from a polymorphic ancestor representing both a photosymbiodeme and a species pair. Indeed, both cases are well documented in other taxa of Pseudocyphellaria. However, our results do not support such a conclusion, but rather indicate step-wise transitions between photobionts and/or reproductive strategy. We also found that P. durietzii and P. hookeri are not photomorphs sharing the same mycobiont, as previously suggested. All four species of the P. hookeri group are described and illustrated and their taxonomy is discussed, including a dichotomous key. We also provide information about their distribution, ecology, and conservation status. We introduce the term “soredisidia” for reproductive structures that represent a transition between genuine soralia and true isidia. This contribution is dedicated to our esteemed colleague, André Aptroot, on the occasion of his 65th birthday.

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