Taxonomic Study of the Lichen Genus Lobaria in South Korea

Lobaria (Schreb.) Hoffm is a common foliose lichen genus found on the Korean Peninsula, yet until now, no revision study has been done on this genus. After careful examination of specimens deposited in the Korean Lichen Research Institute (KoLRI), nine distinct species of Lobaria were confirmed. Morphological characteristics such as the presence or absence of isidia, or whether or not the surface was ridged or smooth, and chemical characteristics such as the result of the medulla reaction were of significant importance in the differentiation of species. Here, we provided detailed descriptions together with a key to all the known Korean species.


Description of the species.
Lobaria adscripturiens (Nyl.) Hue, (1900). Diagnostic characteristics: Thallus is medium to large, 8~10 cm broad; color of the thallus is light brown, olivebrown or occasionally yellow-brown, becoming dark brown on the margins; lobes are 0.4~0.9 cm wide, deeply and irregularly laciniate, margin of the lobes is obtuse, waveshaped; upper surface somewhat ridged, soredia and isidia are absent; lower surface is concolorous with the upper surface, covered with brown or dark-brown tomentum, dark rhizines are present on the lower surface. Photobiont is green algae.
Apothecia are disc-shaped, up to 3 mm in diameter, disc color is dark-brown, spores are acicular, 3-septate, 50 × 6~7 µm. Chemistry: Thallus K−, medulla K−, KC+ red, P−; containing congyrophoric acid and gyrophoric acid. Habitat and distribution: The species is found growing on bark or rock with mosses at altitudes of 1,000~1,500 m. It is reported throughout East Asia and is common in South Korea ( Fig. 2A). Remarks: This species closely resembles L. quercizans but lacks gryphoric acid, and it has a rougher thallus. It could also be confused with L. japonica, but while it contains gyrophoric acid, L. japonica does not. Lobaria discolor (Bory) Hue, (1901). Diagnostic characteristics: Thallus is medium to large, 6~8 cm in diameter, color is greenish gray to olive brown, dark brown at the margin; lobes are rounded and ascending, margin crenulate, slightly wave-shaped, 1~2 cm wide; upper surface is smooth, without soredia, isidia or lobules; lower surface is light brown to yellow-brown, covered with sparse dark-brown tomentum, brown rhizines are present near the center of the lower surface. Photobiont is green algae.
Apothecia are rare, cup-shaped, tan to reddish-brown, adnate and constricted at the base, 3~4 mm in diameter, spores are fusiform (Fig. 1G) at maturity, 35~40 × 9 µm. Chemistry: Thallus K+ yellow; medulla K−, KC+ red; containing gyrophoric acid. Habitat and distribution: The species is found growing on bark around 1,000~1,500 m elevation. Reported to exist in Indonesia [14] and common in South Korea (Fig. 2B). Remarks: Morphologically and chemically, L. discolor is similar to L. quercizans due to absence of isidia and lobules, plain surface and cortex, K+ yellow, medulla K−, KC+ red. The spore of L. discolor is fusiform while L. quercizans has acicular spores. Lobaria isidiosa (Müll. Arg.) Vain., (1913). Diagnostic characteristics: Thallus is medium to large, 10~15 cm broad, color is blue-green when wet, becomes brown or dark brown after dried; lobes are irregularly or delicately branched, truncated at the tips; upper surface has clear reticular ridge, soredia are absent, isidia and lobules are present; flat or cylindrical isidia either single or clustered together along the ridge (Fig. 1B), lobules are irregular and covered with pruinose; lower surface is grayishbrown, covered with dark brown tomentum, growing between naked and gray swellings, brown rhizines are present. Blue-green algae are the photobiont.
Apothecia are on the ridge of the lobes, discs are brown, 2~3 mm in diameter, spores are fusiform, 3-septate, 25~ 30 × 10~12 µm. Chemistry: Thallus K−; medulla K+ red, P+ orange, KC−; containing gyrophoric, constictic, norstictic, stictic and thelephoric acids. Habitat and distribution: Grows on tree bark or on moss growing over rocks at an elevation of 700~1,700 m. It has been reported throughout Eastern Asia but is rare in South Korea (Fig. 2C). Remarks: The species is similar to L. retigera with flat or cylindrical isidia along the ridged portions, but it has the K+ red medulla reaction which contains norstictic and stictic acids. Lobaria japonica (Zahlbr.) Asahina, (1933). Diagnostic characteristics: Thallus is medium to large, 6~15 cm wide, color is dull yellow-brown or olive brown; lobes are irregularly or delicately branched, elongate, rather narrow, 4~12 mm broad, truncated at the top; upper surface is plan and smooth without reticular ridges, sometimes with minor wrinkles; soredia, isidia and lobules are absent on the upper surface; lower surface is lightly brown to brown and covered with dark brown tomentum, mainly in the center part; rhizines are black. Green algae are the photobiont.
Apothecia are common, diffuse on the upper surface, cup-shaped, tan to reddish-brown, adnate and constricted at the base, up to 5 mm in diameter; spores are 4-cell, linear or acicular at maturity, 50~60 × 5 µm. Chemistry: Thallus K−; medulla KC−; no lichen substances detected by TLC. Habitat and distribution: On the bark of trees; it has been reported in Japan and Sakhalin [14]. In South Korea, it is rare (Fig. 2D). Lobaria linita (Ach.) Rabenh., (1845). Diagnostic characteristics: Thallus is 5~15 cm broad, color is greenish to yellowish brown; lobes are irregular and wide, truncate at the tip, 0.5~2.5 cm wide; upper surface is more or less ridged, without soredia, isidia or lobules; lower surface is light yellow-brown, ridged, covered with rare brown rhizines, tomentum are growing between naked and gray swellings. Green algae are the photobiont. Apothecia grow on the ridged part of the surface, discs are 1~4 mm in diameter, constricted at the base, brown to reddish brown; spores are 3-septate at maturity, fusiform, 25~30 × 6 µm. Chemistry: Thallus K−; medulla K−, KC−; containing Tenuiorin and methyl gyrophorate. Habitat and distribution: Grows on rocks or base of trees, usually together with moss at altitudes greater than 1,000 m. It has been widely reported in circumpolar regions but in South Korea, it is rare (Fig. 2E). Remarks: This species might be mistaken for L. retigera due to the ridge on the upper surface but L. linita contains tenuiorin and no isidia, whereas L. retigera lacks tenuiorin and has isidia or lobules.

Lobaria meridionalis Vain., (1913).
Diagnostic characteristics: Thallus is medium to large, 5~8 cm broad, color is grayish green; lobes are deeply and irregularly laciniate, marginal part is obtuse, 0.4~0.9 cm wide; upper surface slightly ridged without soredia, isidia and lobules present, isidia are cylindrical on the ridge and marginal parts (Fig. 1A); lobules are irregular or spoonshaped, growing on the margin of thallus, pruinose on the tip; lower surface is yellow-brown to brown, covered with tomentum which are yellow brown, rhizines are sparse and blackish. Green algae are the photobiont.
Apothecia growing on the ridge and margin, 2~4 mm in diameter, constricted at the base, discs are reddish brown to brown; spores are 3-septate, fusiform, 20~30 × 7~8 µm. Chemistry: Thallus K−; medulla K+ yellow or red, P+ yellow, KC−; contains norstictic, stictic, constictic and cryptostictic acids. Habitat and distribution: On the bark of trees at altitudes greater than 1,000 m. It has been reported throughout Eastern Asia but is uncommon in South Korea (Fig. 2F). Lobaria quercizans Michx., Flora Boreali-Americana 2: 324 (1803). Diagnostic characteristics: Thallus is medium to large, 6~15 cm wide, color is dull gray-brown or brown; lobes are irregularly elongate and narrow, 4~6 mm broad, truncated at the top; upper surface is plain and smooth without reticular ridges, soredia, isidia or lobules are absent; lower surface is light brown to brown, covered with tomentum that are dark brown, mainly in the center part; dark brown rhizines are also present. Green algae are the photobiont.
Apothecia are common, adnate and constricted at the base, 1~3 mm in diameter, cups are reddish-brown; spores are 4-cell and long, linear or acicular at maturity, 35~50 × 5 µm. (Fig. 1E and 1F). Chemistry: Thallus K+ yellow; medulla KC+ red; containing gyrophoric acid, traces of atranorin. Habitat and distribution: On the bark of deciduous trees at altitudes of 600~1,600 m. Reported throughout Eastern Asia and North America [14]. In South Korea it is not common (Fig. 2G). Remarks: Morphologically L. quercizans is similar to L. japonica but is distinguished by containing gyrophoric acid. It also might be confused with L. discolor but it has acicular spores while L. discolor has fusiform spores. Lobaria retigera (Bory) Trevis., Lichenotheca Veneta: no. 75 (1869). Diagnostic characteristics: Thallus is medium to large, 5~12 cm in diameter, color is brown to dark bluish brown; lobes are irregular, 5~10 mm wide; upper surface is ridged, isidia and lobules present, soredia absent; isidia are on the ridge or margin of the lobes, lobulate or cylindrical (Fig.  1C); lower surface is lightly yellow-brown, covered with tomentum and sparse brown rhizines. Blue-green algae are the photobiont.
Apothecia are mostly on the ridge, constricted at the base, discs are brown, 2~4 mm in diameter, and spores are 3-septate, fusiform, 30~40 × 5~7 µm. Chemistry: Thallus K−; medulla K−, P−, KC−; containing triterpenoids and thelephoric acid. Habitat and distribution: Growing on mosses over rocks or on the base of trees at altitudes of 600~1,500 m. It has been reported in Japan, Australia, South Africa and Alaska [14]. It is common in South Korea (Fig. 2H).  (Fig. 1D); lobules are irregular and pruinose on the tip; lower surface is yellowbrown to dark-brown, tomentum are present together with brown rhizines. Green algae are the photobiont.
Apothecia are rare, mostly on ridges and 1~2 cm wide, discs are reddish brown; spores are 3-septate, fusiform, 25~30 × 5~7 µm. Chemistry: Thallus K−, medulla P−, K−, KC+ rose; containing gyrophoric and thelephoric acids. Habitat and distribution: Grows on the bark of trees at altitudes of 700~1,600 m; Reported in Japan and Formosa [14] but in South Korea it is uncommon and generally found in the Northeastern part of the country (Fig. 2I). Remarks: L. spathulata closely resembles L. meridionalis, which has well developed irregular lobules and contains cyanobacteria as phycobionts. However, L. spathulata has flat or lobule-like isidia and contains gyrophoric and thelephoric acids whereas L. meridionalis has cylindrical isidia and contains norstictic acid. Six species were previously recorded on the Korean peninsula [10,11] but not found in our study. They are listed here: Lobaria kurokawae Yoshim., J Hattori Bot Lab 34: 297 (1971). This species was recorded by Huneck et al. [8] in North