Bacidina indigens (Vain.) S. Ekman & J. Gerasimova, 2017

Gerasimova, Julia V. & Ekman, Stefan, 2017, Taxonomy and nomenclature of seven names in Bacidia (Ramalinaceae, Lecanorales) described from Russia, Phytotaxa 316 (3), pp. 292-296 : 294

Bacidina indigens (Vain.) S. Ekman & J. Gerasimova , comb. nov.

MycoBank no.: MB819011 Lecidea indigens Vain. (1909: 104) . Bacidia indigens (Vain.) Zahlbr. (1926b: 208) . Type:— RUSSIA. Chukotka Peninsula: “Sibiria:

Pitlekai, 67° 7’ lat. bor., 173° 24’ long. occid. (Greenw.)”, 1879, E. Almquist s. n. (lectotype, designated here: S L31730!; isolectotype

TUR-V 20776!). Bacidia viridescens auct., non (A. Massal.) Th. Fr. [“(A. Massal.) Norman”, “(A. Massal.) Hellb.”].

The name Lecidea indigens and its combination in Bacidia have so far only been applied to the type material, which was collected on sandy soil on the Chukotka peninsula (although the protologue indicates that it was also observed on weathered bones). The type material of Bacidia indigens is characterized by an esorediate thallus consisting of coalescing granules (pale bluish to bluish grey according to Vainio 1909), flat to moderately convex, brown-black, mostly 0.4–0.8 mm wide apothecia possessing a concolorous, thin margin level with the disk. The proper exciple is paraplechtenchymatous and has red-brown and olivaceous brown pigmentation above, gradually fading to yellowbrown below. The hypothecium is pale yellowish brown (K-), and the hymenium is olivaceous green above, 50–55 μm tall and with abundant paraphyses with clavate apices. Ascospores are acicular, almost straight to more or less helical, 25–40 × (1.5–)2.0 μm, thinly septate (4–5 according to Vainio 1909).

Bacidina indigens turns out to be the earliest available name for the taxon currently known as Bacidia viridescens auct., which is based on Raphiospora viridescens ( Massalongo 1853) . The holotype of the latter name in herbarium VER belongs to the taxon known as Bacidia bagliettoana (A. Massal. & De Not.) Jatta. A full description of this taxon (under the name Bacidia viridescens ) was provided by Coppins & Aptroot (2009). Bacidina indigens is similar to B. egenula (Nyl.) Vězda , which was pointed out by Vainio (1909). The latter has a brown, K+ greenish hypothecium and a finely granular thallus.