Candelariella aggregata M.Westb. Bryologist 110: 393. 2007.

Holoype.

U.S.A. Colorado: Larimer Co., Trail Ridge, 0.5 mi SE of Ranger Station, NW of Tombstone Ridge, 11500-11700 ft alt., 30 June 1962, R. A. Anderson 2229 (COLO!, isotype BRY!).

Candelariella aggregata was recently reported from Europe for the first time from the Murmansk Region in Russia (Urbanavichus and Urbanavichene 2008) and also from Switzerland (Spinelli 2011). It is a terricolous species growing in arctic-alpine areas as well as in dry, steppe-like habitats in North America, Asia and Europe (Westberg 2007b, Westberg and Sohrabi manuscript). It is recognized by its yellow granular to areolate thallus, numerous and often crowded apothecia with a thin margin (Fig. 1). The asci are 8-spored with narrowly ellipsoid spores (14 –)15–18(– 21) × 5.0-6.0 µm . Compared to e.g., Candelariella aurella (Hoffm.) Zahlbr it also has a proper exciple that does not form a distinct stipe below the hymenium and the structure of the exciple is paraplechtenchymatous with thin cell-walls (Westberg 2007b). Candelariella aggregata appears to be common in the continental parts of Switzerland in steppe-like habitats at low altitudes or on well lit calcareous walls on south-facing slopes at higher altitudes.

There is a large variation in thallus morphology, apothecia and in spore size in 8-spored terricolous material in Switzerland. Possibly several species are involved and this group is clearly in need of revision. The name Candelariella unilocularis (Elenkin) Nimis has been used for a terricolous species with a well-developed thallus and long spores but this name is a synonym of Candelariella aurella (Khodosovtsev 2005, Westberg and Sohrabi in press). Material of the long-spored species from the Swiss Alps will be described in a forthcoming paper (Otte and Westberg, in prep.).

Specimens examined.

Graubünden: Ardez, alt. 1491 m, 11 Oct 2007, Vust (G 00298392, G 00298400); sous l’église de Feldis, alt. 1470 m, 6 June 1999, Clerc (G 00298388); Fetan, Mot da l’Hom, alt 2380 m, 24 July 1956, Frey (G 00298391); National Park, Piz Pisoc, 29 July 1934, Frey (G 00298390); Tarasp, alt. 1440 m, 10 Aug 1995, Vust (G 00298398); Tarasp, alt. 1420 m, 12 June 1998, Vust (G 00298389); Valais: Bagnes, LaLy, alt. 2350 m, 24 July 2008, Vust (G 00298397, 00298399); Charrat, alt. 518 m, 2 Oct 2007, Vust (G 00298394); Guttet/Leuk, alt. 1000 m, 18 Oct 1997, Vust (G 00298403); Loèche, alt. 855 m, 7 Aug 1997, Vust (G 00298395); Mauvoisin, alt. 2740 m, 15 Aug 1998, Vust (G 00298413); Mazembroz, alt. 600 m, 28 April 1999, Vust (G 00298402); Rarogne, Heidnischbiel, alt. 759 m, 16 Oct 2007, Vust (G 00122115); Saillon, colline du château, alt. 504 m, 20 Sept 2007, Vust (G 00298396); Saillon, W part of the Saillon hill, alt. c. 500 m, 19 Nov 2010, Westberg 10-178, 10-182 (S F177773, F177825); Vex, les Crêtes, alt. 1083 m, 5 Aug 1996, Vust (G 00298404); Zeneggen, alt. 1315 m, 15 Oct 2007, Vust (G 00298393, G 00298401); Zeneggen, Eich, 1010-1030 m, 19 Nov 2010, Westberg 10-193 (S F178469).