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. 241 zinic acid ........................................ 4. U. glabrescens 7. Mature soralia mostly deeply excavate, ± confluent; fibrils usually abundant; mature thallus normally rela- tively small, usually without salazinic acid ................ ..................................................... 2. U. fulvoreagens 8. Mature soralia tuberculate to slightly excavate; longi- tudinal cracks rare at the basal part; squamatic and/or thamnolic acids present (K–, PD–, or K+ yellow, PD+ yellow-orange) ............................. 7. U. subfloridana 8. Mature soralia usually plane to slightly excavate and often elongated; longitudinal cracks common at the basal part; barbatic and/or salazinic acids or very rarely usnic acid alone present (K–, PD–, or K+ yellow, or- ange or red, PD+ yellow or orange) ........................... ......................................................... 9. U. wasmuthii 1. Usnea diplotypus Vain. Meddeland. Soc. Fauna Fl. Fenn. 48: 172. 1925 (‘1924’). — Type: Finland, Varsinais-Suomi, Turku, Pahaniemi, in latere abrupto rupis graniticae, 1923 Vainio (TUR-V 530!, lectotype, here designated; TUR-V 534a!, isolectotype). Chemistry: usnic and salazinic acids and unknown fatty acid A4/B5/C5 (Clerc 1987a). Thallus erect, more rarely subpendent, to ca. 7(–12) cm long, richly branched. Branching main- ly anisotomic-dichotomous. Branches slender, to ca. 1(–1.5) mm in diam., occasionally with foveo- les or depressions. Annular cracks sometimes slightly constricted, rarely with white medullary rings. Base slightly to distinctly blackened. Cor- tex relatively thin, 7– 9 –10% ( n = 9). Medulla nor- mally lax and relatively thick, 17– 22 –26% ( n = 9). Central axis relatively thick, 33– 40 –47% ( n = 9). Papillae mostly cylindric and numerous. Fibrils usually abundant and often present also near api- cal parts. Soralia ( see Clerc 1987b: 101) minute, usually tuberculate, developing mainly from tu- bercles; soredia usually farinose. Isidia generally numerous and often relatively tall. Chemistry . Strain 1 ( n = 11): usnic + salazinic ± protocetraric acids (trace) ± unknown fatty acid (K+ yellow, orange or red, PD+ yellow or orange); strain 2 ( n = 3): usnic + salazinic + barbatic acids (K+ yellow or orange, PD+ orange). Remarks . Usnea diplotypus is a species close to U. substerilis (Clerc 1987a) and U. lapponica , and they probably belong to the U. rigida agg. (Halonen et al. 1998) in which U. rigida s. lato is the primary, regularly fertile counterpart. The aggregate is characterized by the relatively thin cortex, usually lax and fairly thick medulla, pale to distinctly blackened base and branches which are not clearly tapering and are often ± foveolate. The chemistry of the aggregate is quite variable, but strains with salazinic acid are very common. Furthermore, distributions of the species in the aggregate have continental tendencies. All the East Fennoscandian U. diplotypus specimens are shrub- by to subpendent, but the species is often pendent in Central Europe. Those populations also may have a different chemistry, including a strain with alectorialic acid (Clerc 1987a). Many of the Usnea diplotypus specimens have previously been determined as U. subfloridana (incl. U. comosa and U. similis ), but the latter spe- cies has a mainly isotomic-dichotomous branch- ing pattern, often enlarged soralia, usually shorter papillae and it contains squamatic and/or tham- nolic acids. U. substerilis , which is also an isidiate species, differs by its ± enlarged soralia andminute isidia that are normally present only on young soralia. Ecology . The species has been collected from Picea ( n = 4), Betula ( n = 3), Alnus ( n = 2), Salix ( n = 1), Sorbus ( n = 1) and rocks ( n = 1) (in total 12 specimens). Usnea diplotypus grows in mesic forests and often in inhabited sites. As pointed out by Clerc (1987a: 493), the species is not pri- marily saxicolous as believed by Räsänen (1951) and Carlin and Swahn (1977). Distribution . Finland: 2, 3, 5, 11, 12, 14–16. Russia: 1, 8, 10. World distribution: Europe, with continental tendencies, and Pacific coast of North America (Clerc 1987a, Halonen et al. 1998). Us- nea diplotypus is apparently rare and southern in East Fennoscandia, but it is easily confused with modifications of some other species and thus it may have been overlooked. Selected specimens examined . — Finland . Varsinais- Suomi: Naantali, Luonnonmaa, Käkölä, 1961 Klingstedt (H), strain 1. Uusimaa: Espoo, 1926 Mannermaa (OULU), strain 1. Satakunta: Kankaanpää, 1935 Laurila (H), strain 1. Pohjois-Savo: Kuopio, Levänen, 1941 Räsänen (H), strain 1. Pohjois-Karjala: Kaavi, Peuramäki, 1941 Räsänen (H), strain 2. Oulun Pohjanmaa: Kiiminki, Takalankylä, 1973 Ulvinen (OULU), strain 2. Perä-Pohjanmaa: Kemi, Niemelä, 1864 Brenner (H), strain 1. Russia . Leningrad Region. Kare- lia australis: Yashino (Vahviala), Hämeenvaara, 1938 Fa- gerström (H), strain 1. Republic of Karelia. Karelia pomorica occidentalis: between Syargozero (Särkijärvi) and Padany (Paadene), 1942 Huuskonen (H), strain 1. Regio kuusamoën- sis: Paanajärvi National Park, Niskakoski, 1938 Laurila (H), strain 1.