Cetraria steppae Savicz is conspecific with Cetraria aculeata (Schreb.) Fr. according to morphology, secondary chemistry and ecology

Abstract

AbstractEurasian Cetraria steppae and the more widely distributed C. aculeata are two lichen species traditionally distinguished by Eastern European and Spanish lichenologists on the basis of their morphological and ecological characteristics. Other specialists, however, consider them puzzling. This paper aims to evaluate the taxonomic status of these members of the C. aculeata group and thereby to clarify their conservation status in Ukraine. Morphological, chemical and ecological features of specimens originating from populations in different regions of Ukraine were tested and compared with the main characteristics commonly used for the species delimitation. Neither morphological nor chemical traits were found to correlate with ecological characteristics on a small geographical scale. Variation in the norstictic acid content detected in 256 individuals from 13 populations in Ukraine showed no correlation with the morphological characteristics that are currently used for species delimitation. These morphological features appear to vary continuously and did not support subdivision among the specimens studied. We hypothesize that C. steppae and C. aculeata are conspecific, and provide a formal synonymy. Specimens with norstictic acid are regarded as a different chemotype. Possible evolutionary and adaptive roles of norstictic acid in C. aculeata s. lat. are discussed. Based on current and historical data, we consider C. aculeata s. lat. as vulnerable in Ukraine, according to the IUCN criteria for regional Red List assessment.