Buellia asterella Poelt & Sulzer, Nova Hedwigia 25: 182-184 (1974).
Thallus white, upper surface mealy to finely granulose, rosette-forming, lobes contiguous, 0.2 to 0.5 mm wide. Upper cortex to 75 µm thick, no cellular structures recognizable, consisting of a layer of Ca-oxalate crystals, dead hyphae and dead algal cell walls (determined as CZJ+ violet), in polarized light yellow. Algal layer ca. 80 µm high, pale green, more or less continuous. Medulla completely filled with Ca-oxalate crystals, white-bluish in polarized light; thallus underside with rhizines in places.
Apothecia always present, round to slightly oval, black, mostly not pruinose, 0.1-1 mm diam (but mostly less than 1mm) broadly to narrowly adnate. Disc flat to slightly convex (older apothecia), margin visible in young, flat discs, white pruinose, disappearing in older, convex discs. Exciple to 60 µm wide, more or less radiating, not very well developed, lacking crystals, mostly uniformly brown, sometimes lighter within, crystals deposited on the outside. Hypothecium to 100 µm tall, light to medium brown, lacking crystals. Hymenium hyaline, rarely >70 µm; epihymenium 10-15 µm tall, yellow-brown (green-brown in fresh material). Paraphyses 2.5-3.5 µm [wide], terminal cells with brown pigment caps 3.5-5 µm wide. Ascus with eight spores, of which only four achieve maturity.
Ascospores 2-celled, sometimes lightly curved, not or only slightly constricted at the septum, with a thin halo as the outermost layer, light brown to brown to transparent; outer wall visible as a sharply demarcated line; torus unclear; epispore finely structured, possibly microfoveate, spores (10-)10.9-13.6-16.3(-19) x (4.5-)5.3-6.5-7.7(-8.5) µm (n = 142).
Pycnidia: very rare, oval, completely immersed, openings as small dark points on the thallus surface, resembling young apothecial starts; conidia bacilliform, 5-8 x 1-2 µm.
Chemistry: atranorin, norstictic acid. In 64 samples atr + norst was found, in 13 only atranorin and in 4 no secondary metabolites. One sample contained atranorin and stictic acid.
Description translated from: Trinkaus & Mayrhofer (2000).
Buellia asterella used to occur in isolated patches of dry grassland from Italy to England and southern Norway. It appears to have had its centre of occurrence in the central German Mittelgebirge. Today it is thought to be extinct at all but three or four localities globally. The only British site was last confirmed in 1991 and two of the four German sites documented in the last 30 years were visited in 2015 and the species could not be found. The immediate causes for its disappearance appear to be outright loss of grassland habitat to agricultural and urban development, eutrophication (through fertilizer drift, the sites being surrounding by rapeseed fields), shrub and grass encroachment and trampling of sites where suitable habitat would otherwise still exist.
Criterion A. We assume for this species a generation time of 30 years, estimating the time for population reduction record - and application of criterion A - as ca. 100 years. According to criterion A1ac the species could be listed as VU (there are possibly two current, though unconfirmed sites from Germany and 3 from Norway in this century and there were eight more c. 20 years ago); according to A2bc, A3c it could be listed as EN given the fast decline in the species occurrences and anticipated complete loss of all populations within the next generation cycle; and according to A4c it is CR because of the past loss and expected loss of all known sites due to ongoing effects that are only partly understood.
Criterion B. The strong decline in geographic range through loss of verifiable occurrences qualifies Buellia asterella for consideration as EN according to B2ab (AOO=44 sq. km).
Criterion C. does not apply.
Criterion D. Does not apply.
Final recommendation: Buellia asterella has been assessed as CR according to A4c at the global level.
An endemic of western European low elevation dry grasslands; Italy to the British Isles and Norway. The majority of all sites found over time were in the German lowlands and “Mittelgebirge”.
A recent literature report of B. asterella from India (Rai & Upreti 2014) is clearly in error. The specimen from 3300 m alt. is depicted in Fig. 2.4 of that work and clearly belongs to Phaeorhiza sareptana var. sphaerocarpa (H. Mayrhofer, Graz, pers. comm. 26 Jan 2015).
Because of the extinction of numerous localities in the 20th century only few localities left; French, Italian and Swiss records before 1960.
The last record from Lakenheath Warren seems to be 05/07/1994, Peter Lambley, TL752804. Any later sightings should find their way to the BLS Database.
The last record for Thetford Heath seems to be 1986, Vince Giavarini, but with GR just as TL78. Previous to that the most recent record is by Peter James, Peter Lambley & Chris Hitch, 09/05/1983, TL840790 - said not to be re-found here in 1991.
The last record for Deadman’s Grave seems to be 09/12/1982, Peter Lambley & G.P. Radley, TL776742.
There is also a report from Weeting Heath SSSI, of 1972, Peter Lambley, TL758879, “a few thalli in one small area”.
Outside of Breckland there is the 19th Sussex record: Chene Gap, Peacehaven,TQ40, by J. Hemmings in 1868. There are also (?earlier) specimens labelled Rottingdean, and later given the GR of TQ30, but the sites are close and could well have been all the same place! Francis Rose, Simon Davey and myself looked carefully along the coast there in the 1970s & 80s, but there is little intact habitat left, being mostly ‘developed’ for housing, caravan parks and recreational uses.
“the status is very bad, it is known from a handful localities in two small areas. It is extinct in one area, in the other area some localities are destroyed by cattle trampling. In the Norwegian red list database, we estimate 4.5 current localities, 27 specimens, i.e. category CR based on criteria C1+2a(i) and D1.” (E. Timdal, pers. comm., e-mail to T. Spribille dated 09 Jan 2015)
Status of Buellia asterella in Norway:
(from Reidar Haugan & Einar Timdal, pers. comm. to T. Spribille 2015-01-28)
The species occurs in two areas in the «steppe» area of the Gudbrandsdal valley in Southeast Norway.
The first area, in Dovre municiality, «NE of the Dovre railway station, 1948» (loc. 1) has been searched for in vain by Haugan and Timdal but no suitable site is known. The locality is probably overgrown by shrubs/trees or destroyed.
The second area, the S-facing slope north of lake Vågåvatn in Vågå municipality («Nordherad») consists of seven population sites within a radius of 2 km (loc. 2-8). Sites 2-7 are in the old cultural landscape near farms, site 8 in natural vegetation at 930 m.
2. Vistehorten nature reserve. Strongly degraded by trampling of goats. Buellia asterella is probably much reduced but may still exist (latest observed in 2010).
3. Rock outcrops east of the Vistehorten nature reserve. The site is still intact. A few specimens of B. asterella observed by Haugan in 2005. Latest observation in 2010.
4. Rock outcrops below the farm Ulvsbu, Sandehorten nature reserve. Our latest visit was in 2002. The species was still present, but very sparingly. Present situation unknown.
5. Sande (1958), 6. Fellese (1981), 7. Vistdal (1948). Haugan and Timdal have searched in vain for suitable habitats near these farms. Buellia asterella is probably not here anymore.
8. The brook Svarthamarbekken. Recently discovered (2013) site in steep slope. Population size unknown.
“Je n’ai pas trouvé personnellement cette espèce en France et n’ai donc que les données de la littérature (que vous avez certainement). Pas d’observation récente. ” (C. Roux, pers. comm., e-mail to T. Spribille 27 Jan 2015)
Most historical collections are documented by Trinkaus & Mayrhofer (2000). Note that the species was so abundant at localities in the 19th century that exsiccates (mass collections) could be or were made at Krögelstein (1866), Allach, now a suburb of Munich (in 1888 and 1894), and at Lechfeld near Augsburg (date unknown).
An effort has been made to reach out to amateurs and professionals in Germany with information on possible recent occurrences of the species in that country. The species has been documented twice from Thuringia: “Meinunger L., Haussknechtia Beiheft 16, 2011: p. 19, cites 2 collections from Thuringia: (1) “Zechstein-Orlasenke: 5335/141 Brandenstein, auf Kalksand, 16.10.1967, leg. R. Marstaller, ... det. J. Poelt (Poelt & Sulzer 1974), (2) “5335/122 Felsenberg S Öpitz, mit Solorinella asteriscus, 15.1.2011, leg. L. Meinunger (a habit photo of this collection is shown on p. 134).
Schöller H., Cezanne, R., Eichler, M., Rote Liste der Flechten Hessens, 1996: p. 21, lists B. asterella as Red List Status 1 (threatened with extinction).” (C. Printzen, pers. comm. to T. Spribille, Jan. 2015).
Three sites were recorded in northern Hessen between 1986 and 2005 (Dietmar Teuber, pers. comm. to T. Spribille, 28 Jan 2015).
Note that the recent Meinunger record is only 2.2 km distant from the other most recent central European record, by R. Marstaller in 1967 (T. Spribille, pers. obs., Feb. 2015).
The species appears to be extinct from the Tiesberg dry grassland near Iversheim (North Rhine-Westfalia) (F. Bungartz, pers. comm., 29 Jan 2015).
no records are known other than the historical record cited by Trinkaus & Mayrhofer (2000).
The Swiss locality “Tardisbrücke”, near Landquart (canton of Grisons) could not be confirmed so far. The river of Rhine has been channelized in this part and the old bridge was replaced by a larger one to suit the modern traffic in 1892 (C. Scheidegger, pers. comm., 2015). However, the species was abundant enough at this locality in the 19th century that it was twice collected for mass distribution to herbaria (exsiccates by Hepp and Rabenhorst, thought to be B. epigaea at the time).
Population Trend: Deteriorating
Buellia asterella grows on limestone, dolomite or gypsum soils in dry grasslands (see photo), primarily temperate dry grasslands of central Europe. It is not a component of Eurosiberian dry grasslands that extend to the east or the Pannonian basin.
Buellia asterella appears to be very vulnerable to the impact of habitat changes and destruction. Many of the previous sites such as Allach near Munich, and sites on dolomite in Franconia, northern Bavaria, have been completely converted either to suburban developments or to agriculture. Fragmentary sites in northern Hessen that are contained in nature reserves are embedded in heavily utilized agricultural landscapes dedicated especially to rapeseed cultivation and are subjected to fertilizer drift. Furthermore, potential habitats such as gypsum grasslands are popular sites to visit for recreation and the dry gypsum domes on which appropriate Fulgensia-dominated lichen communities develop are often heavily trampled by tourists.
The species occurs in or near habitats which are often resampled by phytosociologists who collect species for ecological plots (e.g. a site in Hessen is an annual excursion site for the University of Göttingen); collecting of this species and all other members of its lichen community should be strictly forbidden.
Buellia asterella is red-listed in Germany, Switzerland and the United Kingdom of Great Britain and Ireland, as well as France.
Kålås, J.A., Viken, Å., Henriksen, S. og Skjelseth, S. (red.). (2010) Norsk rødliste for arter 2010. Artsdatabanken, Norge.
Poelt, J. & Sulzer, M. (1974) Die Erdflechte Buellia epigaea, eine Sammelart. Nova Hedwigia 25: 173-194.
Rai, H. & Upreti, D.K. (2014). Terricolous lichens in India. Vol. 2: Morphotaxonomic studies. Springer.
Trinkaus, U. & Mayrhofer, H. 2000. Revision der Buellia epigaea-Gruppe (lichenisierte Ascomyceten, Physciaceae). I. Die Arten der Nordhemisphäre. - Nova Hedwigia 71(3-4): 271-314.