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

240 Halonen • ANN. BOT. FENNICI 36 (1999) (1998), and Stevens (1999). Chemotypes may be more or less artificial, since compounds may oc- casionally occur in very low amounts and there- fore be overlooked in TLC studies. TAXONOMY Descriptions given in the key and under the spe- cies refer to the variation present in the East Fenno- scandian material. Norstictic and salazinic acids give K+ yellow and PD+ yellow reactions in low concentrations, but turn slowly to orange or red at higher concentrations (the CK reagent gives re- actions similar to the K reagent with norstictic and salazinic acids). The provincial distribution of each species in Finland and Russian Fennoscan- dia is given using the traditional biogeographic provinces (Fig. 1). Key to the shrubby Usnea species in East Fennoscandia 1. Papillae absent (very rarely present); cortex thin and medulla normally thick and lax ............................... 2 1. Papillae present (may be absent in juvenile thallus); cortex and medulla various ...................................... 3 2. Soralia minute; isidia numerous; fatty acids normally present (usually K–, PD–); common ........ 5. U. hirta 2. Soralia large; isidia absent; protocetraric acid group normally present (K– or K+ brownish, PD+ red-orange); rare ...................................................... 3. U. glabrata 3. Branches mainly anisotomic-dichotomous; never with stictic acid group, squamatic or thamnolic acids present ................................................................................. 4 3. Branches mainly isotomic-dichotomous; stictic acid group, squamatic or thamnolic acid may be present (ex- cept in U. wasmuthii ) ............................................... 6 4. Mature soralia deeply excavate; isidia absent ........... .......................................................... 6. U. lapponica 4. Mature soralia tuberculate to slightly excavate; isidia normally present at least on young soralia .............. 5 5. Mature soralia enlarged, plane to slightly excavate; isidia short, often sparse and may be present only on young soralia .................................... 8. U. substerilis 5. Mature soralia punctiform, with numerous tall isidia .. ......................................................... 1. U. diplotypus 6. Isidia very rare; stictic acid group normally present .. ................................................................................. 7 6. Isidia present at least on young soralia; never with stictic acid group ................................................................ 8 7. Mature soralia mostly plane to slightly excavate, dis- crete; fibrils usually sparse at least near apical parts; mature thallus normally relatively tall, usually with sala- Table 2. Main secondary medullary metabolities in the shrubby species of Usnea in East Fennoscandia. + = present in all specimens examined, ± = present in some specimens, – = not present, a = accessory substance, not important for taxonomy and often present in small amounts, * = the strain may represent a hybrid. BAR = barbatic acid, CNSTI = connorstictic a., Cph-1 = convirensic a., Cph-2 = confumarprotocetraric a., CPSO = 2’- O -demethylpsoromic a., CRSTI = cryptostictic a., CSTI = constictic a., DBAR = 4- O -demethylbarbatic a., DIF = diffractaic a., FAT = fatty acids (the murolic acid complex in U. hirta and usually caperatic acid in U. lapponica ), FUM = fumarprotocetraric a., NSTI = norstictic a., PRO = protocetraric a., PSO = psoromic a., SAL = salazinic a., SQU = squamatic a., STI = stictic a., THA = thamnolic a. ———————————————————————————————————————————————————————————————————————— DIF BAR DBAR SQU THA Cph-1 Cph-2 FUM PRO NSTI CNSTI STI CSTI CRSTI SAL PSO CPSO FAT ———————————————————————————————————————————————————————————————————————— Usnea diplotypus – ± a – – – – – a – – – – – + – – a Usnea fulvoreagens ± – – – – – – – a ± a ± a a ± – – – Usnea glabrata – – – a – a a a ± ± a – – – ± – – a Usnea glabrescens – – – – – – – – a ± a ± a a ± – – – Usnea hirta – – – – – – – – – ± – – – – – – – ± Usnea lapponica – – – – – – – – a – – – – – ± ± a ± Usnea subfloridana – – – ± ± – – – – – – – – – – – – – Usnea substerilis – ± a – – – – – a ± * – – – – ± – – a Usnea wasmuthii – ± a – – – – – a – – – – – ± – – – ————————————————————————————————————————————————————————————————————————