Ionaspis alba (Ascomycotina, Hymeneliaceae), a New Lichen Species from Eastern North America

Abstract

Ionaspis alba sp. nov., described from the Appalachian-Great Lakes region, is a lichenized ascomycete superficially resembling I. odora and sharing morphological characteristics with Hymenelia lacustris. It is characterized by olive-gray to brownish-gray thalli, small whitish to lightbrownish apothecial disks, thin subhymenium, small ascospores, short conidia, trebouxioid photobiont, and the lack ofan epihymenial pigment and epipsamma. It is a xerophilous and sciophilous species of small boulders in temperate deciduous forests of eastern North America. In a study on generic redelimitation of the Ionaspis-Hymenelia complex (Lutzoni 1990; Lutzoni & Brodo 1995), a distinctive xerophilous and sciophilous lichen-forming ascomycete was discovered growing on small boulders in deciduous forests of the Appalachian-Great Lakes region. No other species of Ionaspis or Hymenelia is known in this habitat or to have a distribution restricted to this region. A statistical analysis of anatomical and morphological data recorded from North American material of these two genera corroborates the unique characteristics of this lichen suggested by the ecology and phytogeography (Lutzoni & Brodo 1995) and justifies its recognition as a new species. In the following description of the new species, the numerical codes included in parentheses and adjacent to color descriptions represent colors recorded using the U.S. National Bureau of Standards (Kelly & Judd 1976) and a chart of centroid colors (Kelly 1965). Measurements are usually given by five numbers [ex. (1.5-)4.0-8.5-13.5(-27.0)]. The numbers in parentheses are the most extreme measures recorded. The two numbers that are not in parentheses and not underlined are the lower and upper limit of the standard deviation applied to the average. The underlined number is the overall av-