Synonym: Letharia togashii Asah., J. Jap. Bot. 27: 295. 1952.
The species was described as a Letharia (Asahina 1952) and later transferred to the genus Lethariella according to morphological-anatomical and chemical characters (Krog 1976). It is the only species of the subgenus Nipponica; the latter is characterized by the solid and elastic axis, like in Usnea, but with soft, reticulately ridged cortex. The genus Letharia is morphologically separated from Lethariella mainly by the lacerate axis. The yellow-coloured thallus due to vulpinic acid is distinct in Letharia; this substance is also present in the medulla of Lethariella togashii but due to the low concentration not always recognizable as yellow pigment (Obermayer 1997; Ohmura 2011).
Global distribution of Lethariella togashii is limited to only six locations in Japan and Russian Far East. In Japan, it has been recorded in Hokkaido (2 locations, extant) and in central Honshu, around Mt. Fuji, but in this area the species has not been found after 1950s, and is considered extinct at present. It is also known from Russia: Sakhalin, Kunashir Isl. and adjacent region in Habarovsk krai (Sikhote-Alin Mts), all 3 locations are extant. The species is treated as a relict from the last glacial period and its distribution area in Japan has declined (Kashidawani & Inoue 2000; Y. Ohmura, pers. comm.). It is also under threat in Russian locations by the destruction of habitats (montane coniferous forests), possibly due to human activities – forest fires and tree cutting (Russia’s Boreal Forests 2007).
A criterion: population reduction during last 100 years has been estimated ca 17% as 1 location (Japan, central Honshu) out of 6 is considered extinct. It qualifies NT according to A2(c).
B criterion: AOO is calculated 20 km2 (considering 5 extant localities and IUCN suggestion that AOO of 1 location = 4 km2). Using B2(a,b) the species qualifies EN because of AOO is max. 40 km2 even assuming undiscovered populations (twice as many as currently recorded), and because of the exclusively fragmented nature of the species range (no one known locality can be treated as a stronghold for this taxon).
C and D criteria: not applicable as relevant numbers of individuals are not available; E criterium: not applicable as no quantitative analyses have been carried out.
Decision: Lethariella togashii is assessed EN according to the criterium B2ab.
The species is known from Japan (Honshu and Hokkaido) and the Far East of Russia (islands Sakhalin and Kunashir, and Sikhote-Alin in Habarovsk region), altogether from 6 localities.
1. Japan, central Honshu, Prov. Kai (Yamanashi Prefecture), Minamitsuru-gun distr., leg. M. Togashi 11.08.1952 (type; distributed in Lichenes Rariores Et Critici Exsiccati 66); by Lake Yamanaka, Mt. Fuji, leg. M. Togashi 14.07.1953 (H; distributed in Lichenes Japoniae Exsiccati 26).
2. Japan, Hokkaido, Prov. Kushiro, Mt. O-akan (Akan), leg. Y. Ohmura 10.08.2009 (Ohmura 2011).
3. Japan, Hokkaido, Nemura (List of endangered lichen species. Lethariella togashii. 2003. http://www.kahaku.go.jp/research/db/botany/chii-e/05/zchii019.htm).
4. Russia, Far East, island Sakhalin (Skirina 2006).
5. Russia, Far East, Habarovsk krai, Sikhote-Aline (Skirina 2006).
6. Russia, Far East, Kurile Isl., Kunashir, leg. A. Ezhkin 2014.
Lethariella togashii is a very rare species but no detailed assessments of population size and its decline exist. One subpopulation out of six (ca 17%) is considered extinct. Further decline by the destruction of habitats (montane coniferous forests) due to human activities, forest fires and tree cutting, is possible.
Population Trend: Deteriorating
On bark of coniferous trees (e.g. Abies, Picea) in coniferous stands in lower elevations (700-1000 m) of mountain forests.
Destruction of habitats (montane coniferous forests), possible due to either human activities or natural causes – forestry (tree cutting) and forest fires.
Ecological studies to find out more about the aut- and synecology of the species, which would contribute to the future knowledge about possible threats and relevant conservation measures.
Asahina, Y. 1952. Lichenologische Notizen §85–87. Journal of Japanese Botany 27: 293–296.
Kashiwadani, H. & Inoue, M. 2000. Lichens. In: Environment Agency. Threatened Wildlife of Japan – Red Data Book 2nd ed.Vol. 9, Bryophytes, Algae, Lichens, Fungi, pp. 259–312. Japan Wildlife Research Center, Tokyo.
Krog, H. 1976. Lethariella and Protousnea, two new lichen genera in Parmeliaceae. Norwegian Journal of Botany 23: 83–106.
List of endangered lichen species. Lethariella togashii. 2003. http://www.kahaku.go.jp/research/db/botany/chii-e/05/zchii019.htm
Obermayer, W. 1997. Studies on Lethariella with special emphasis on the chemistry of the subgenus Chlarea (Lichenological results of the Sino-German Joint Expedition to south-eastern and eastern Tibet 1994. IV). In: Türk, R. & Zorer, R. (eds) Bibliotheca Lichenologica 68: 45–66. J. Cramer in der Gebr. Borntraeger Verlagsbuchhandlung, Berlin-Stuttgart.
Russia’s Boreal Forests 2007. WWF for a living planet. http://www.wwf.ru/about/what_we_do/forests/eng
Skirina, I. F. 2006. Lethariella togashii (Parmeliaceae), a rare new species to the lichen flora of Russia from the southern Far East. Botanicheskii Zhurnal (St. Petersburg) 91: 1114–1116.
Ohmura, Y. 2011. Notes on eight threatened species of lichens in Japan. Bulletin of the National Museum of Nature and Science, Series B, 37: 55-61.