Petrova O. The lichen genus Usnea in eastern Gennoscandia. III Shrubby species. Ann. Bot. Fennici. 1999, 36, p. 235-256.

ANN. BOT. FENNICI 36 (1999) • Usnea in East Fennoscandia. III. 245 or fusiform at bases, apices often recurved. An- nular cracks normally sparse, ± constricted, some- times with thin, everted medullary rings. Base usually constricted to fusiform, pale to slightly blackened. Cortex somewhat shiny, thin, 4– 5 –7% ( n = 12). Medulla loosely arachnoid, thick, 32– 36 –39% ( n = 12). Central axis thin, 13– 18 –23% ( n = 12). Papillae absent or occasionally low and sparse, very rarely tall and numerous. Fibrils usu- ally abundant. Soralia mostly near the apices, tu- berculate to distinctly excavate (especially when eroded in old herbariummaterial), relatively large, often becoming confluent, developing from plane cortex or from tubercles; soredia ± granulose. Isi- dia absent, but isidia-like spinules are occasion- ally present on soralia. Chemistry . Strain 1 ( n = 46): usnic + protoce- traric + fumarprotocetraric acids ± convirensic acid ± confumarprotocetraric acid ± squamatic acid (1 specimen) (K– or K+ brownish, PD+ red- orange); strain 2 ( n = 2): usnic + salazinic + nor- stictic ± stictic (trace) ± connorstictic (trace) + protocetraric (trace) acids + unknown fatty acid A6/B3 (K+ orange or red, PD+ yellow). Remarks . Usnea glabrata is the only repre- sentative of the U. fragilescens agg. in East Fenno- scandia. The aggregate is charactarized by the shiny, normally thin cortex, lax medulla and thin central axis and by the branches that are often fairly swollen and fusiform to constricted at the bases (Clerc 1987a, Halonen et al. 1998). The chemistry is very variable, however. Most of the species in the aggregate are distinctly oceanic or have oceanic tendencies in their distributions. Us- nea glabrata normally has at most low and sparse papillae, but strain 2 specimens have tall and abun- dant papillae. Furthermore, one thallus is excep- tionally tall (ca. 10 cm), part of the thalli has an- nular cracks with everted medullary tissues, and the chemistry is unusual. They resemble in chem- istry some thalli of the type material of U. barbata var. pilina and U. sorediifera . It is possible that the strain 2 specimens are hybrids of U. glabrata and another species. Ecology . The species has been collected from Alnus ( n = 24), Picea ( n = 10), Betula ( n = 4), Salix ( n = 4), Populus ( n = 2) and Sorbus ( n = 1) (in total 45 specimens). The species is likely to be most common in moderately open and humid mixed forests, and it often occurs along shores of water-courses and in inhabited areas. Distribution. Finland: 5–8, 11, 12, 15–17, 19; Russia: 2–5. World distribution: circumpolar in boreal and temperate regions with continental ten- dencies (Myllys 1994). Usnea glabrata mainly occurs in southeastern regions of East Fennoscan- dia being very rare elsewhere (map by Myllys 1994: 128). There is only one U. glabrata collec- tion from East Fennoscandia from last decades (Oulun Pohjanmaa, Kuivaniemi, Taipale, 1989 Halonen , OULU) and the species is regarded as vulnerable in Finland and in the Republic of Kare- lia (Kotiranta et al. 1998). Usnea glabrata has a conspicuous morphology, but it may easily be- come overlooked in the field because of its small size, however, and there are relatively sparse new Usnea collections fromPohjois-Savo and Pohjois- Karjala which form the main distribution area of the species in Finland. Specimens examined .—East Fennoscandian herbarium specimens were listed byMyllys (1994). The following ones are additions. Finland . Pohjois-Savo: Tuusniemi, Laukansa- lo, 1924 Räsänen (H), strain 2; Kuopio, Rauhalahti, 1950 Nauha (OULU), strain 1. Pohjois-Karjala: Värtsilä, 1949 Huuskonen (H), strain 1. Perä-Pohjanmaa: Tervola, Koivu, 1936 Ahlner (S), strain 1. Koillismaa: Kuusamo, Joukamo- järvi, Taivalperä, 1936 Ahlner (S), strain 1. Russia . Repub- lic of Karelia. Karelia ladogensis: Kurkijoki, Otsanlahti, 1932 Räsänen (H), strain 2; Kurkijoki, Riekkala, 1933 Räsä- nen (S), strain 1. 4. Usnea glabrescens (Nyl. ex Vain.) Vain. ex Räsänen Luonnon Ystävä 23: 9. 1919. — Usnea barbata (L.) F. H. Wigg. var. glabrescens Nyl. ex Vain., Meddeland. Soc. Fau- na Fl. Fenn. 2: 46. 1878. — Type: Russia. Leningrad Re- gion, Karelia australis, Vyborg (Viipuri), Vysotsk (Uuras), ad corticem betulae, 1875 Vainio (TUR-V 708!, holotype). Chemistry: usnic, salazinic (trace) and norstictic acids. Usnea extensa Vain., Ann. Acad. Sci. Fenn., Ser. A4, 27 A(6): 68. 1928. — Type: Russia. Sibiria, Tyumen Re- gion, Leuschi (Levusch) by the Konda River, 1880 Vainio (TUR-V 558!, lectotype, here designated; TUR-V, four iso- lectotypes). Chemistry: usnic, salazinic and norstictic acids (TLC by P. Clerc). Usnea glabrescens var. glabrella Motyka, Wydaw. Muz. S l a sk. Katowice, Dzia l 3, 2: 24. 1930. — Usnea gla- brescens subsp. glabrella Motyka, Usnea 1: 301. 1936. — Usnea glabrella (Motyka) Räsänen, Ann. Mus. Nat. Hung. 33: 117. 1940. —Type: Ukraine (Poland). CarpathianMts., Chernohory (Czarnohora), Mt. Pozyzewska, ad Picea , 1929