The Ramalina intermedia Complex in North America

Abstract

Ramalina intermedia has a North American distribution ranging from New Brunswick south along the eastern seaboard, inland throughout Quebec and Ontario, and has been reported from the Northwest Territories and Alberta. This species is abundant in the Great Lakes region, and has been collected in mountainous areas of Colorado, New Mexico, and Arizona. This species has a single chemical race in North America containing sekikaic, homosekikaic, and usnic acids and variably possessing atranorin and an unknown. Fertile thalli are reported from North America. A new species, Ramalina petrina, is described from the Appalachian Mountains. This small sorediate species is characterized by conspicuous terminal soralia borne on recurved lobe tips. Ramalina petrina is PD+ and contains protocetraric acid, usnic acid, and atranorin. Ramalina intermedia is one of the most widespread, yet most often misidentified small sorediate species of Ramalina in North America. Although it is common and abundant in much of its range and is well represented in herbaria, the species has been poorly understood. It is the purpose of this study to clarify the chemical ecology and distribution of this species in North America. The distribution of R. intermedia is sympatric, in part, with R. farinacea, R. pollinaria, and R. roesleri. All three are species with which it has been confused. Examination of herbarium specimens and field collections has shown that R. intermedia consistently contains sekikaic and homosekikaic acids. The identity of homosekikaic acid in R. intermedia was determined by Chicita Culberson (pers. comm.). Surveys of thallus chemistry were carried out by thin-layer chromatography with Merck Silica Gel F254 pre-coated glass plates using a benzene:dioxane: acetic acid (90/25/4, v/v/v) solvent system as described by Culberson and Kristinsson (1970). Microextraction was effected upon thallus fragments using warm acetone. The plates were developed with 10% H2SO4 and heat. All of the 140 thalli tested by thin layer chromatography contained sekikaic, homosekikaic, and usnic acids. Atranorin and an unknown (Rf class 3 in this solvent system) were found in a few plants. Usnic and homosekikaic acids appeared to vary greatly in concentrations, occasionally present only in trace amounts. Taylor (1968) reported no medullary acids in individuals of R. intermedia from Ohio. We have been unable to confirm the existence of this strain in our studies. Ramalina intermedia has a much broader ecological amplitude and range of substrate This content downloaded from 164.67.185.210 on Fri, 18 Jul 2014 18:06:56 PM All use subject to JSTOR Terms and Conditions 618 THE BRYOLOGIST [Volume 77