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A new lichenicolous fungus, Opegrapha sphaerophoricola Isbrand & Alstrup, is described from Sphaerophorus globosus in North America. Opegrapha is a genus comprising lichenized as well as lichenicolous fungi. The family Opegraphaceae has recently been investigated for the Mediterranean area (Torrente & Egea 1989), but many of the lichenized species in Northern Europe are still insufficiently known and a revision is highly needed. The lichenicolous species are much better known, and a key to these was published by Clauzade et al. (1989). One additional new species on Stereocaulon has recently been described (Alstrup & Hawksworth 1990). However, some lichenicolous fungi presently placed in the genus Leciographa may have to be incorporated in Opegrapha. The known lichenicolous species of Opegrapha are found on a variety of lichen genera, e.g., Brigantiaea, Clathroporina, Dermatocarpon, Lecanora, Parmelia, Pertusaria, Phaeorrhiza, Thelotrema, Staurothele, and Xanthoria. The genus has a worldwide distribution. The new species described here was collected by the first author during a holiday, which also included sporadic collecting of lichens in diverse habitats in British Columbia and adjacent parts of the United States. OPEGRAPHA SPHAEROPHORICOLA Isbrand & Alstrup sp. nov. (FIG. 1-4) Fungus in lichene parasiticus. Ascomata nunc dispersa, nunc aggregata, plus minusve connata, tumuliformia, valde convexa, e verticibus visa rotundata, non ramificata, sessilia vel basibus immersa, nigra, ad circiter 1 mm diam. Epithecium 5-10 Atm altum, fusco-nigrum; hymenium 6070 Atm altum, achroum, hyalinum; hypothecium fusconigrum, 50-60 Atm altum, pseudoparenchymaticum, e cellulis compositum rotundatis vel angulatis, 6-8 tm diam. Excipulum sensim in hypothecium transiens, initio hymenium paene tegens, post dilatatum. Paraphyses ramificatae, anastomosantes, 2 tm crassae. Asci clavati vel anguste clavati, fovea interna apicali rostriformi in tholum impressa, 50-65 x 13-16 Am magni, octospori. Ascosporae anguste ellipsoides, ad apices rotundatae, ternis septis divisae, initio achroae, hyalinae, aetate provecta substantia obscura extra irregulariter deposita pictae, 19-22.5 x 5.5-6 Am magnae. Nullae partes jodo coloratae, nec recentes nec 10% KOH tractatae. HOLOTYPUS: CANADA. BRITISH COLUMBIA. Vancouver Island, Kennedy River, ca. 5 km from the outlet to Kennedy Lake, between road no. 4 and the river, on Sphaerophorus globosus growing on Alnus sp. close to the river, 3 May 1989, S. Isbrand (c). Lichenicolous fungus. Ascomata dispersed to aggregated-stromatic, rounded, not branched, strongly convex, sessile or immersed at base, base not constricted, black, to about 1 mm diam.; epithecium 5-10 im high, brown-black; hymenium 60-70 im high, hyaline, hypothecium brown-black, 50-60 im high, pseudoparenchymatic, cells rounded to angular, 6-8 im diam.; exciple contiguous with hypothecium, when young almost covering the hymenium, later expanding; paraphyses branched and anastomosing, 2 im thick; asci clavate to narrowly clavate, with a tholus with an internal apical beak

A total of 218 taxa of lichens, including one lichenicolous fungus, is reported from Tuxedni Wilderness area in western lower Cook Inlet, Alaska. Lecanora epanora, Micarea denigrata, and Trapeliopsis flexuosa, are new to Alaska. Xanthoria alaskana Thomson sp. nov. is described. Compared with lichen distribution in British Columbia, the lichen flora of the Tuxedni area falls into five distributional categories, the majority of species occurring in coastal, wet interior, and alpine and subalpine ecological-geographic subdivisions. The most important northern hemisphere distributional categories are wide-ranging circumpolar arctic-alpine and boreal, western North American, and amphi-Beringian.

Four lichens-Parmelia bolliana Mull. Arg., Physcia stellaris (L.) Nyl., Xanthoria fallax (Hepp) Am., and Physconia grisea (Lam.) Poelt--listed in order of decreasing mesophytism, were fumigated for 4 hr at 0.01, 0.1, 1.0, and 2.5 ppm sulfur dioxide to determine the effects on photosynthesis, respiration, and chlorophyll content. The lichens had been collected from Populus deltoides Marsh or Tilia americana L. in northeastern South Dakota near a lignite-fired power generator. Photosynthesis decreased after fumigation at 1.0 and 2.5 ppm, but significant decreases occurred only after fumigation at 2.5 ppm. Expressed on the basis of per unit weight chlorophyll content, photosynthesis of Physconia grisea was most sensitive followed by that of Xanthoria fallax, Physcia stellaris and Parmelia bolliana. Expressed on the basis of per unit dry weight of lichen sample, photosynthesis of Physconia grisea was most sensitive followed by Xanthoria fal- lax, Physcia stellaris, and Parmelia bolliana. In both cases, the more xerophytic species were more sensitive. Chlorophyll content in these species was not mea- surably altered by fumigation. Comparison of chlorophyll a and b absorption spec- tra peaks for fumigated and control samples indicated that no phaeophytinisation occurred. Insignificant and inconsistent differences in chlorophyll a/b ratios were observed. Respiration of Physcia stellaris and Parmelia bolliana decreased signif- icantly following fumigation with 2.5 ppm S02; both species were more sensitive than Xanthoria fallax. Physconia grisea was not tested for respiratory responses. The effects of S02 fumigation on measured metabolic rates differed with the species. Photosynthetic rates of the xerophytic Xanthoria fallax and Physconia grisea were more sensitive than the more mesophytic Parmelia bolliana and Phy- scia stellaris. In contrast, respiratory sensitivities to S02fumigation were greater for P. bolliana and P. stellaris. It is well known that lichens are sensitive to air pollution, particularly to sulfur dioxide. Field studies from a variety of locations have reported evidence of the phytotoxicity of sulfur dioxide. Hawksworth's (1971) review of the literature is comprehensive; studies done since 1971 have left his basic conclusions unchanged. Experimental studies to examine the basis of lichen sensitivity have produced inter- esting results, which in some cases are not altogether consistent with field observations. Summaries of experimental studies have been presented by Gilbert (1973) and Nieboer et al. (1976). Experimentally, lichens have been exposed to both low and high concentrations of sulfur dioxide. In studying the effects of exposure on photosynthesis, Pearson & Skye (1965) used concentrations ranging from 102 ppm to 105 ppm. Puckett et al. (1973) used

DISTRIBUTION. X. parietina, a very common lichen in Europe, has a unique pattern of distribution along both coasts of North America and the lower Gulf of Mexico (fig. 5). It is strictly oceanic and does not extend inland more than a few miles (excepting one locality on the Connecticut River in Vermont). The species name parietina in North America has unfortunately been assigned in the literature to other species of Xanthoria, including X. candelaria, X. fallax and X. polycarpa.