Morphological disparity in Cladoniaceae: The foliose genus Heterodeaevolved from fruticose Cladiaspecies (Lecanorales, lichenized Ascomycota)

Phylogenetic relationships of the genera Cladiaand Heterodeawere reconstructed using a combined dataset of nuclear ITS, nuclear LSU and mitochondrial SSU rDNA sequences. Based on different analyses (Bayesian approach, maximum parsimony, maximum likelihood), the ingroup (Cladia+ Heterodea) is strongly supported as monophyletic. Pilophorus strumaticushas a well supported sister–group relationship to the ingroup and together they form a sister group with a well–supported clade, which includes Metus conglomeratusand Pycnothelia papillaria. The Shimodaira–Hasegawa test and the ELW test significantly rejected monophyly of Cladiaexcluding Heterodea. Within Cladiathree main clades can be distinguished which share morphological and chemical characters. The position of the foliose genus Heterodeawithin the fruticose Cladiais supported by anatomical and chemical characters. The species of clade II that includes two Cladiaspecies and Heterodeashare a similar type of upper cortex and two–layered medulla with an inner or lower medulla consisting of dark pigmented, thick–walled hyphae. Our phylogenetic estimate and the anatomical studies indicate that the foliose thallus of Heterodeaoriginated from pseudopodetia of Cladia. It is discussed that the species currently classified in Cladiaand Heterodeaneed to be placed in the same genus.