Differing from other Sticta species in having a stipe, up to 1 cm long, a palmate thallus with abundant, submarginal to laminal apothecia, with the primary tomentum absent in the marginal parts of the thallus and a secondary tomentum present.

Bolivia. Dept. La Paz; Prov. Nur 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 17263 & P. Rodriguez-Flakus (holotype KRAM, isotype LPB).

Primary photobiont cyanobacterial (Nostoc). Stipe present, up to 1 cm long. Thallus palmate, up to 10 cm diam., moderately branched, with 3–5 branches per 5 cm radius, branching anisotomous to pleurotomous; lobes suborbicular to flabellate, interspaced to adjacent, involute, with their apices rounded and plane and their margins entire to sinuous, not thickened; lobe internodes (4–)6–15(–20) mm long, (6–)10–10(–20) mm broad; thallus coriaceous. Upper surface smooth to shallowly rugose in some parts, brown-grey, darker in the margins, shiny; surface glabrous, without papillae and pruina, without maculae; marginal cilia abundant, agglutinated to fasciculated, dark brown with pale tips, up to 0.5 mm long. Apothecia abundant, principally submarginal to laminal, dispersed, subpedicellate, sessile, up to 1.5 mm diam.; disc reddish-brown, shiny (in young apothecia) to matt (in older); margin entire to weakly crenate, excipulum hairs few to dense. Vegetative propagules absent. Lower surface folded to distinctly ridged and forming a reticulate pattern especially towards the margins, yellowish-brown to brown towards the centre; primary tomentum scarce, absent in the marginal part of the thallus, fasciculate, soft, golden brown; secondary tomentum present, arachnoid, up to 25 μm. Rhizines absent. Cyphellae 1–20 per cm² towards the thallus centre and 21–40 per cm² towards the margin, scattered, irregular to elongate or rounded, urceolate with narrow to wide pore, prominent, on the same level as the primary tomentum or below, with the margin raised and involute to raised and involute-circinate, brown coloured, with or without tomentum; pore (0.25–)0.5–1(–2) mm diam.; basal membrane smooth, white, K+ yellowish, C–, KC–, Pd–. Medulla loose, white, K± yellowish, C–, KC–, Pd–. No substances detected by TLC.

Upper cortex paraplectenchymatous, 20–50 μm thick, differentiated into two cellular layers, the upper layer consisting of 1–2 layers of cells, with cells 5–6 μm diam., their walls 1–2 μm thick and their lumina rounded to isodiametric, 4–6 μm diam.; the lower layer of cortex 2–3 layers of cells, with cells 8–15 μm diam., their walls 1–2.5 μm thick and their lumina rounded to isodiametric, 3–5 μm diam. Photobiont layer 20–60 μm thick, its cells 6–12 μm diam. Medulla 100–220 μm thick, its hyphae 3–5.5 μm broad, without crystals. Lower cortex paraplectenchymatous, 20–50 μm thick, with 2–4 cell layers; cells 8–17 μm diam., their walls 2–4 μm thick. Hairs of lower primary tomentum up to 220 μm long and 3–5 μm broad, in groups to rarely simple, in fascicles up to 15, hyphae unbranched, septate, with free apices forming a brush-like head. Cyphella cavity up to 120 μm deep; membrane of cells densely packed, cells of basal membrane with 2–4 papillae. Apothecia biatorine, ca. 500 μm high, without distinct stipe; excipulum up to 120 μm broad, without or with projecting hairs, simple to fasciculate. Hymenium 100–120 μm high, hyaline, but K+ yellow; epihymenium ca. 10 μm high, orange-brown, K+ orange intensifying, without gelatinous upper layer. Asci 6–8-spored, ascospores fusiform, 2–4-septate, 31–37 × 8–9 μm.

Stictacatharinae is known only from the type locality in Yungas forest in the Department La Paz.

The new species is named to honour our late friend and teacher, Polish botanist Dr Katarzyna Żółkoś, for her contributions to the conservation of nature.

Stictacatharinae is the only species amongst those newly described here that is characterised by the presence of a stipe supporting the thallus. Morphologically, this taxon is similar to S.aff.caliginosa D. J. Galloway and the cyanomorph of S.neopulmonarioides B. Moncada & Coca, which share the stipe and the palmate thallus. However, in S.aff.caliginosa and S.neopulmonarioides, no apothecia are known, whereas vegetative propagules in the form of isidia or phyllidia and lobules are present (Galloway 1997; Moncada 2012; Moncada et al. 2013a). In addition, these taxa differ in the shape of the lobes and the presence of marginal cilia. In S.aff.caliginosa, the lobes are ligulate to flabellate, with their apices rounded to obtuse and with cilia being sparse to absent (Moncada 2012). In contrast, S.neopulmonarioides has flabellate lobes with irregular apices, without cilia (Moncada et al. 2013a). Stictaneopulmonarioides is widely distributed in Colombia, while S.aff.caliginosa is a rare taxon in that country (Moncada 2012; Moncada et al. 2013a, 2014b).

The new species is closely related to S.fuliginoides (Fig. 1; Suppl. material 3: Fig. S1), a morphologically disparate taxon with broad lobes producing laminal isidia (Magain and Sérusiaux 2015). It is also phylogenetically quite distinctive from the latter, with a total of 16 substitutions and nine indels in the ITS (Suppl. material 2: File S1), warranting its formal description, based on a single collection only.