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

242 Halonen • ANN. BOT. FENNICI 36 (1999) 2. Usnea fulvoreagens (Räsänen) Räsänen Lich. Fenn. Exs. no. 13 (Schedae: 5). 1935. — Usnea glabrescens (Nyl. ex Vain.) Vain ex. Räsänen var. fulvorea- gens Räsänen, Ann. Acad. Sci. Fenn. Ser. A4, 34(4): 20. 1931. — Type: Estonia. Virumaa, Vägeva, 1924 Kari (TUR!, syntype). Chemistry: usnic and thamnolic acids. — The collection (two thalli) represents Usnea subfloridana . — Other syntypes: Estonia. Saaremaa, Kuressaare, an Lärche, and Kihelkonna, an Picea excelsa , 1929 Räsänen (not found). — Proposed conserved type: Russia. Republic of Karelia, Kurkijoki, Lapinlahti, 1923 Räsänen (H!). Chem- istry: usnic, norstictic, stictic, cryptostictic and constictic acids ( see also Clerc 1987a: 494). Usnea fulvoreagens f. incolorascens Räsänen, Ann. Bot. Soc. Zool. Bot. Fenn. Vanamo 12(1): 50. 1939. — Type: Russia. Republic of Karelia, Karelia ladogensis, Kurkijoki, Lapinlahti, ad corticem alni, 1932 Räsänen (H!, lectotype, here designated). Chemistry: usnic and constictic (trace) acids. — Syntypes: Russia. Republic of Karelia, Karelia ladogensis, Kurkijoki, Majalampi, ad corticem alni, 1932 Räsänen (H!), andMaasilta, ad corticem alni, 1933 Räsänen (S!). Chemistry: usnic and constictic acids in both syntypes. Thallus (Fig. 2) erect, rarely subpendent, to ca. 10(–15) cm long, sparsely to more often richly branched, branches occasionally very densely ar- ranged. Branching mostly isotomic-dichotomous. Branches normally slender, up to ca. 1.3(–1.8) mm in diam., apices quite often recurved. Annular cracks ± abundant, often with thick medullary rings (Fig. 3). Base distinctly blackened. Cortex usually relatively thick, 8– 11 –15% ( n = 28). Me- dulla lax to dense, generally relatively thin, 8– 14 –20% ( n = 28). Central axis relatively thick to thick, 38– 50 –58% ( n = 28). Papillae usually cy- lindric, abundant on main branches. Fibrils nu- merous to very dense, rarely sparse. Soralia deeply excavate when mature with torn cortex around them, often confluent; soredia farinose. Isidia ab- sent. Chemistry . Strain 1 ( n = 97): usnic acid + vari- ous combinations of compounds of the stictic acid group ± protocetraric acid (trace) (K+ yellow, orange or red, PD+ yellow or orange, or K–, PD– when only low amounts of compounds); strain 2 ( n = 7): usnic + salazinic + norstictic acids ± other compounds of the stictic acid group ± protocetraric acid (trace) (K+ yellow, orange or red, PD+ yel- low or orange); strain 3 ( n = 5): usnic + diffractaic ± norstictic ± connorstictic acids (K+ yellow, or- ange or red, PD+ yellow or orange, or K–, PD– when the stictic acid group is absent); strain 4 ( n = 1): usnic + unknown substance A2/B2 + traces of unknown substances (K+ yellowish, PD–). Norstictic acid is present in most specimens of strain 1. There are also many specimens which solely contain very low amounts of constictic acid, in addition to usnic acid ( Usnea fulvoreagens f. incolorascens according to Räsänen, since it does Fig. 2. Shrubby thallus of Usnea fulvoreagens (Rä- sänen)Räsänenwithdense branches and fibrils. From 1929 Räsänen (H). Scale = 1 cm.