Rusavskia, S.Y.Kondr. & Kärnefelt, 2003

Vondrák, Jan, Frolov, Ivan, Davydov, Evgeny A., Yakovchenko, Lidia, Malíček, Jiří, Svoboda, Stanislav & Kubásek, Jiří, 2019, The lichen family Teloschistaceae in the Altai-Sayan region (Central Asia), Phytotaxa 396 (1), pp. 448-450 : 448-450

Rusavskia (including Zeroviella ) ( Figs 11 , 12A–C )

At least 5 species recorded in the region occurring on various inorganic substrates, but rarely also on bark, organic soil or bryophytes. Thallus is foliose or crustose with marginal lobes. Vegetative dispores are present in two species (blastidia in R. sorediata , lobules in R. dasanensis ). Apothecia are known in all species, but sometimes not developed. Taxonomy is not settled and our species delimitation is provisional, reflecting ITS tree topology ( Fig. 11 ) and phenotypic variability. Literature: Arup et al. (2013), Khodosovtsev et al. (2004), Kondratyuk & Kärnefelt (2003), Kondratyuk et al. (2013b, 2015).

Rusavskia dasanensis : 24 localities at altitudes 250–3140 m in arid (rarely humid) habitats. Substrate: sun-lit limestone and siliceous rocks. Hardly distinguished from R. papillifera , R. digitata , and R. domogledensis . ITS sequences from Altai specimens are close to available R. dasanensisis sequences. The Mediterranean R. papillifera belongs to a different clade. Lichens from Altai-Sayan region are morphologically variable; with flat thallus outgrowths (characteristic for R. papillifera ) or with coralloid isidia ( R. dasanensis ). Identities of European R. digitata , and R. domogledensis are not clear.

Rusavskia elegans sensu lato (specimens with small thalli), Fig. 12A right: 34 localities at altitudes 220–2900 m in all ecological categories. Substrate: limestone and siliceous rocks.

Rusavskia elegans sensu lato (specimens with large thalli), Fig. 12A left: 4 localities at altitudes 1400–1800 m mostly in arid or humid alpine habitats. Substrate: siliceous or calcareous rocks exposed to sun.

Rusavskia sorediata : 4 localities at altitudes 220–1800 m in all ecological categories except arid alpine. Substrate: base-rich siliceous and calcareous rocks.

Rusavskia sp. 1 , Fig. 12B : 8 localities at altitudes 250–1400 m in arid, rarely humid, non-alpine habitats. Substrate: limestone. Easily distinguished from other Rusavskia in the region by flat yellow lobes resembling species of Xanthoria . It is common on limestone in forest-steppe zone at northern slopes of Altai.

Rusavskia sp. 2 , Fig. 12C : Single specimen recorded at altitude 1570 m in arid non-alpine habitat (Vondrák 18161). Substrate: siliceous rock (schist). In the ITS tree ( Fig. 11 ), its sequence MG954150 groups with R. elegans , but it is distinguished by lobes tightly appressed to substrate, and cortex and algal layer modified into algal and fungal stacks (see Vondrák & Kubásek 2013).

Figures

FIGURE 11. Bayesian phylogenetic reconstruction of Rusavskia using the ITS DNA locus. Sequences from the Altai-Sayan region are indicated by arrows.

FIGURE 12. Rusavskia (A–C) and variability in Variospora sororicida (D–E). A, Rusavskia elegans (Vondrák 18104), large and small morphotypes included, both are distinct in ITS; B, Rusavskia sp. 1 (Vondrák 18102) with Xanthoria-like flat lobes; C, Rusavskia sp. 2 (Vondrák 18161) with appressed lobes to substrate; D, Variospora sororicida (Vondrák 18071) with strongly reduced thallus on Pyrenodesmia; E, V. sororicida (Vondrák 18680) with few distinct areoles, on Pyrenodesmia; F, V. sororicida with numerous areoles, not obviously lichenicolous (Vondrák 18223).All bars, 1 mm.