35 Opuscula Philolichenum, 9: 35-38. 2011. Punctelia eganii, a new species in the P. rudecta group with a novel secondary compound for the genus BRENDAN P. HODKINSON 1 & JAMES C. LENDEMER 2 ABSTRACT. – Punctelia eganii, a lichen species from southeastern North America, is described as new to science. This species is known from a single locality in Alabama, U.S.A, and is morphologically identical to P. rudecta, differing in the production of lichexanthone, a secondary compound previously unknown in the genus. The use of secondary chemistry in the species-level taxonomy of Punctelia is discussed. INTRODUCTION The genus Punctelia Krog represents a distinctive group of parmelioid species distinguished by having small pseudocyphellae (‘punctae’) in the upper cortex (Krog 1982). The genus has recently been shown to exhibit a greater degree of alpha-diversity in eastern North America than previously reported (Lendemer & Hodkinson 2010, Wilhelm & Ladd 1987). Species in the genus are distinguished by a combination of characters including underside color, secondary chemistry, presence/absence of scrobiculae on the upper surface, and diaspore-type (Lendemer & Hodkinson 2010). A population that is morphologically identical to P. rudecta (Ach.) Krog, but has an alternative secondary chemistry was recently discovered and is described here as P. eganii. This represents the first reported occurence of lichexanthone in the genus Punctelia. MATERIALS AND METHODS Specimens were studied dry using a Bausch & Lomb StereoZoom 7 dissecting microscope and subjected to chemical analysis using standard spot tests (reagents are abbreviated following Brodo et al. (2001)) and Thin Layer Chromatography (TLC). TLC was carried out by R.S. Egan at OMA following Culberson & Kristinsson (1970). Images were captured using an Olympus DP20 digital camera with Microsuite Special Edition. The illustration was prepared using Adobe Photoshop. Due to the limited material available, measurements are expressed simply as ranges of observed values. THE NEW SPECIES Punctelia eganii Hodkinson & Lendemer sp. nov. Mycobank #561203. PLATE 1 (PAGE 36). Sicut Punctelia rudecta sed lichexanthonum continens. TYPE: U.S.A. ALABAMA. MONROE CO.: Haines Island Park, forest trail near boat ramp, public recreation area operated by the U.S. Army Corps of Engineers, 20 mi N of Monroeville, along the Alabama River, 50 ft. elev., beech-Magnolia forest, 31.vii.2003, on bark, R.S. Egan 16197-A (NY, holotype). 1 BRENDAN P. HODKINSON – Department of Biology, Box 90338, Duke University, Durham, NC 27708, U.S.A. – e–mail: brendan.hodkinson@duke.edu 2 JAMES C. LENDEMER – The New York Botanical Garden, Institute of Systematic Botany, Bronx, NY 10458, U.S.A. – e–mail: jlendemer@nybg.org