Differing from S.narinioana in the presence of laminal isidia and in the absence of apothecia, as well as the less densely arranged cyphellae.

Bolivia. Dept. La Paz; Prov. Nor Yungas, Parque Nacional y Área Natural de Manejo Integrado Cotapata, near Urpuma colony, 16°13'20"S, 67°52'34"W, elev. 1989 m, Yungas montane forest, 30 June 2010, A. Flakus 17220 & P. Rodriguez-Flakus (holotype KRAM, isotype LPB).

Primary photobiont cyanobacterial (Nostoc). Stipe absent. Thallus orbicular to irregular, up to 5 cm diam., sparsely branched, with 0–2 branches per 5 cm radius, branching pleurotomous; lobes suborbicular to flabellate, interspaced to adjacent, plane to undulate, with their apices rounded and revolute and their margins entire to sinuous, not thickened; lobe internodes (1–)2–4(–7) mm long, (3–)5–6(–10) mm broad; thallus subcoriaceous. Upper surface smooth to pitted or rugose towards the centre, brownish-yellow with darker apices in the herbarium, shiny; surface glabrous, without papillae and pruina, but with irregular, scattered, yellow maculae; marginal cilia absent. Apothecia absent. Vegetative propagules present, abundant, in the form of isidia, predominantly laminal, aggregate, richly branched from the beginning, isidial branches cylindrical to coralloid, vertical, up to 0.6 mm long and 0.05 mm broad, darker than the thallus, grey, shiny; in cross-section, round or rarely slightly flattened. Lower surface with somewhat elevated, diffuse ridges, yellow to brown towards the centre; primary tomentum dense to the margin, thick but thinner towards the margin, spongy to fasciculate, soft, golden to chocolate; secondary tomentum present, arachnoid. Rhizines absent. Cyphellae sparse, 1–10 per cm² towards the thallus centre and 1–20 per cm² towards the margin, scattered, angular to irregular, urceolate with wide pore, prominent, remaining below the level of the primary tomentum, with the margin raised and involute, cream-coloured, with or without tomentum; pore 0.25–0.75 mm diam.; basal membrane ± smooth, white, K–, C–, KC–, Pd–. Medulla compact, cream, K–, C–, KC–, Pd–. No substances detected by TLC.

Upper cortex paraplectenchymatous, 15–40 μm thick, consisting of 2–3 cell layers with cells 7–18 μm diam. (with smaller cells in outside parts of the cortex), their walls 0.6–2 μm thick and their lumina rounded to isodiametric, 6–17 μm diam. Photobiont layer 25–70 μm thick, its cells 4–20 μm diam. Medulla 30–70 μm thick, its hyphae 2.5–6 μm broad, without crystals. Lower cortex paraplectenchymatous, 30–50 μm thick, with 3 cell layers; cells 6–20 μm diam., their walls 2–4 μm thick. Hairs of lower primary tomentum 150–400 μm long, in fascicles of more than 20, hyphae simple, septate with interlocked apices. Cyphella cavity up to 130 μm deep; cells of basal membrane without papillae or with single papillae. Apothecia not observed.

Stictaaymara is known only from the type locality in the Department La Paz, at an altitude of 1989 m.

The name refers the Aymara people in the Andes and Altiplano regions of South America who coined the term Yungas.

Although this new taxon is known from a single collection only, we decided to describe it formally, as the material is well-developed and phylogenetically distinctive, shown by two sequences generated from different pieces of the specimen. Stictaaymara forms a sister clade with the also newly-described S.narinioana from Colombia (see below). Both taxa produce isidia, but in S.narinioana, they are concentrated along the thallus margins and horizontally orientated, while in S.aymara, they are laminal and upright. Moreover, sparse, submarginal apothecia, absent in S.aymara, were observed in S.narinioana. Cilia are absent in both taxa, but in S.narinioana, the white tomentum projects beyond the edge of the lobes and resembles cilia. The two species also differ in the abundance of cyphellae, which are more densely arranged in S.narinioana.

The presence of isidia is also characteristic for S.isidiokunthii B. Moncada & Lücking and S.weigelii, amongst other similar species (Moncada 2012). However, isidia in these species are mainly marginal and differ in colour. In S.aymara the isidia are grey, in S.isidiokunthii, greenish-brown to brown and in S.weigelii, blackish-brown. Moreover, the latter taxa are characterised by thalli larger than S.aymara, up to 10–15 cm in diam. Differences were also observed in the structure and colour of the lower surface. In S.isidiokunthii, it is uneven, beige to dark brown, while in S.weigelii, it is smooth to undulate, beige to red-brown (Moncada 2012; Moncada and Lücking 2012; Ossowska 2021). Additionally, S.isidiokunthii also produces laminal apothecia (Moncada and Lücking 2012). The medulla of both S.isidiokunthii and S.weigelii reacts with K, while in S.aymara, it is K negative.

The small size of the thalli, the presence of isidia and the absence of apothecia is also characteristic of S.viviana A. Suárez & Lücking. However, this taxon has a dark brown, scrobiculate to faveolate upper surface with cream-coloured maculae. Furthermore, the lower part is rugose to undulating, rather than ridged-veined as in S.aymara. The medulla of S.viviana is K+ orange-yellow and the cyphellae are K+ yellow. The latter species is known from Colombia and Costa Rica (Moncada 2012; Suárez and Lücking 2013; Moncada et al., unpub.). Stictaaymara and S.viviana are phylogenetically only distantly related (Fig. 1; Suppl. material 3: Fig. S1).