Rostania revised: testing generic delimitations in Collemataceae (Peltigerales, Lecanoromycetes)

Abstract

Here, we test the current generic delimitation of Rostania (Collemataceae, Peltigerales, Ascomycota) utilizing molecular phylogeny and morphological investigations. Using DNA sequence data from the mitochondrial SSU rDNA and two nuclear protein-coding genes (MCM7 and β-tubulin) and utilizing parsimony, maximum likelihood and Bayesian phylogenetic methods, Rostania is shown to be non-monophyletic in the current sense. A new generic delimitation of Rostania is thus proposed, in which the genus is monophyletic, and three species (Rostaniacoccophylla, R.paramensis, R.quadrifida) are excluded and transferred to other genera. Rostaniaoccultata is further non-monophyletic, and a more detailed investigation of species delimitations in Rostania s. str. is needed. The new combinations Leptogiumparamense and Scytiniumquadrifidum are proposed.

Species delimitation in the cyanolichen genus Rostania

“…Our study [29] further showed that R. occultata is not monophyletic in the current circumscription. To some Fig.…”

“…We produced 218 new sequences (Additional file 1) (53 mtSSU rDNA, 37 β-tub, 26 MCM7, 42 RPB2 5-7 and 34 RPB2 7-11) and added 26 relevant published sequences [26,29]. The concatenated matrix included 63 terminals.…”

“…This includes all species within Rostania s. str. as delimited by our previous study [29] and the two varieties accepted in R. occultata [28,30]. Most of the collections result from our own recent fieldwork, and are complemented by recent herbarium samples from areas we have not covered.…”

“…PCR amplifications were performed using Illustra™ Hot Start PCR beads, according to manufacturer's instructions. PCR-reactions were performed using the same settings as in previous studies [25,29,70]. We assembled and edited DNA sequences using Geneious version R8 (http://www.geneious.com) [71].…”

“…occultatum, and was found in the south of Scandinavia completely restricted to Populus as a substrate. In our earlier study [29], Rostania was shown to be monophyletic, when only three of the currently accepted species (R. ceranisca, R. multipunctata and R. occultata) were included in Rostania s. str. In this restricted sense Rostania was characterized by a crustose to subfoliose thallus, with initially immersed apothecia which only become sessile late in the development, and with a disc that is concave when young and never convex.…”