Umbilicaria rhizinata Krzewicka 2010

Umbilicaria rhizinata (Frey & Poelt) Krzewicka (2010: 491) Mycobank no. 548351

Umbilicaria decussata (Vill.) Zahlbr. var. rhizinata Frey & Poelt (Poelt 1977: 419).

Type:— NEPAL. Mahalangur: Himal Khumbu, Moränen des Lobuche-Gletschers bei Lobuche, elev. 4950–5000 m, September 1962, J. Poelt L247a (lectotype M–0035585!; isolectotype M–0035586!).

Umbilicaria aprina Nyl. var. halei Llano (1956: 183), syn. nov. Type:— CANADA. N.W.T.: Baffin Island, head of Clyde Fiord, on exposed gneiss boulders, 26 August 1950, M. E. Hale 450 (holotype MIN–664956!, Fig. 1).

The holotype specimen of U. aprina var. halei has a similar morphology to the Himalayan U. rhizinata: small size, dark grey granulate upper surface, lower surface covered with black patches of thalloconidia in the central part only, and scarce dichotomous pale rhizinomorphs (Fig. 1). Thalloconidia are sphaerical to ellipsoid, brown to dark brown 3- or 4-celled when mature, but often also 2- or rarely 1-celled (Fig. 2). The sizes were (12.6–)15.0–16.2–17.5(–18.7) × (10.7–)12.6–13.7–14.9(–16.5) μm for (3-)4-celled (n=25), (11.6–)12.8–13.7–14.9(–16.5) × (8.0–)8.7–9.7–10.7(–11.7) μm for 2-celled (n=25), and (8.1–)9.3–10.3–11.4(–12.0) × (7.6–)8.5–9.5–10.6(–11.4) μm for 1-celled thalloconidia (n=25). The wall was 1.3–1.8(2.8) μm. The average size for all types of thalloconidia is 10.9–13.6–16.4 × 8.8–11.0– 13.2 μm which agrees well with the data presented by Krzewicka (2010) for U. rhizinata. All the remaining characters of U. aprina var. halei also perfectly fit the circumscription of U. rhizinata, except, none of the three specimens of the U. aprina var. halei holotype has a distinct reticulate pattern at the centre. They are coarsely pruinose with crystals positioned centrally near the umbo, but lack a reticulate pattern. Additionally, examined specimens from the Altai Mts. are only occasionally reticulate at the centre. This can be explained by the smaller size of both the holotype and the Altaian specimens (0.8–1.3 cm v. 1–2(–3) cm of U. rhizinata). As has been shown in phylogenies (Davydov et al. 2017), U. rhizinata is closely related to U. aprina, and only distantly related to U. decussata, which consistently possesses this reticulate pattern. Therefore, this character should be used with care as a diagnosis for U. rhizinata. Thus, it is proposed that U. aprina var. halei be reduced to synonymy with U. rhizinata.

Umbilicaria rhizinata resembles immature U. aprina, but differs in its 3–4 celled thalloconidia. Due to the different conception of U. aprina var. halei by Wei & Jiang (1993) who did not pay attention to thalloconidium septation, material cited by them should be re-identified. Based on the information on the apothecia of U. aprina var. halei given in Wei & Jiang (1993) their material probably belongs to U. aprina. Umbilicaria rhizinata was previously known from Nepal and Stanovoye Nagor’e Highlands (South Siberia, Russia) in Asia, Tanzania in Africa, and Bolivia in South America (Poelt 1977, Krzewicka 2010, Davydov et al. 2019a). Further populations in the Altai Mts. both in Russia and China are recorded here. So, we have at least one verified locality for China – in Xinjiang.

Selected specimens examined. RUSSIA. Altai Territory: Altai Mts., Korgonsky range, headwaters of Sentelek River, 51°03’ N, 83°43’ E, elev. 1900–2200 m, mountain tundra, 19 August 1996. E. A. Davydov 5350 (ALTB); Republic of Altai: Katunsky range, Ak-Kem River, stone fields and rocks, 49°59’15.6’’ N, 86°35’09.3’’ E, elev. 2686 m, 9 August 2009. E. A. Davydov 6879 (ALTB).— CHINA. Xinjiang: South Altai range, 49°01’41’’ N, 86°50’38’’ E, elev. 2300–2600 m, 17 July 2007. Davydov 6542 (ALTB).