Differing from S. humboldtii in the absence of true cilia, the presence of submarginal apothecia with entire to crenate margins, completely to partly covered by white hairs, spongy to fasciculate primary tomentum, and scabrid basal membrane of cyphellae, white to yellow (then K+ purple), or partly brown.

Figure 2. 

Morphology of Sticta flakusiorum (holotype) A upper surface B lower surface C, D hirsute upper surface with apothecium and lower surface with tomentum and cyphellae E apothecia with entire to crenate margins, covered by white hairs F primary tomentum spongy to fasciculate and cyphellae with scabrid basal membrane. Scale bars: 1 mm (A–F).

Bolivia. • Dept. La Paz; Prov. Bautista Saavedra, Área Natural de Manejo Integrado Nacional APOLOBAMBA, between La Curva and Charazani, 15°08'09"S, 69°02'03"W, 3780 m, open area with shrubs, Ceja de Monte Superior (Altimontano), on shrub, 15 Nov. 2014, M. Kukwa 14677 (holotype UGDA L-65223, isotype LPB).

Stipe absent. Thallus orbicular, up to 5 cm diam., moderately branched, with 3–5 branches per 5 cm radius, branching pleurotomous to polytomous; lobes suborbicular to flabellate, interspaced to adjacent, involute, with their apices rounded, revolute, and undulate and their margins sinuous, slightly thickened; lobe internodes 2–20 mm long, 3–15 mm broad; thallus coriaceous. Upper surface pitted to rugose, yellowish brown to chocolate brown, darker near the apices in the herbarium, shiny; lobes entirely hirsute or rarely with some parts lacking tomentum, covered by white hairs, without papillae and maculae; true cilia absent, but lower tomentum partly projecting beyond the margins and resembling cilia, fasciculated to agglutinated, white to pale brown, up to 0.5 mm. Apothecia submarginal and laminal, subaggregated, sessile to shortly stipitate, with pronounced invagination on the lower side, up to 2.0 mm diam.; disc brown to chestnut-brown; margin entire to crenate, completely to partly covered by white hairs, up to 1 mm long, simple to agglutinated, margin brown to dark brown. Vegetative propagules absent. Lower surface ribbed, brown; primary tomentum dense and usually thick to sparse to the margin, spongy to fasciculate, soft, white to brown; secondary tomentum present, arachnoid. Rhizines absent. Cyphellae 1–20 per cm² towards the thallus center and 41–60 per cm² towards the margin, scattered, elongate to irregular, urceolate with wide pore to cupuliform, erumpent to sessile, remaining below the level of the primary tomentum, with the margin raised and involute to erect, cream to brown colored, with tomentum up to the pore; pore up to 1.5 mm diam.; basal membrane scabrid, white to yellow, or partly brown, when yellow K+ purple and C+ red-orange, KC–, P–. Medulla compact, white to yellow, or partly brown, when yellow K+ purple and C+ red-orange, KC–, P–. No substances detected by TLC.

Upper cortex paraplectenchymatous, up to 35 μm thick, uniform, up of 5 layers of cells, their walls up to 1.5 μm thick and their lumina rounded to isodiametric, up to 5–15 × 5–10 μm diam. Photobiont layer up to 150 μm thick, its cells up to 10 μm diam. Medulla up to 120 μm thick, its hyphae up to 5.0 μm broad. Lower cortex paraplectenchymatous, up to 50 μm thick, with up to 7 cell layers; cells up to 10 μm diam. Upper primary tomentum up to 100 μm long, simple or in fascicles formed of up to 7 hyphae, hyphae simple. Upper secondary tomentum not seen on upper surface. Lower primary tomentum up to 200 μm long, composed of fascicles formed of 10–15 hyphae, hyphae mostly simple, apically free, and flexuous. Lower secondary tomentum 30 μm long, of single, simple to branched hairs, moniliform. Cyphellae cavity up to 220 μm deep; cells of basal membrane without or rarely with up to 2 papillae. Apothecia biatorine, up to 500 μm high, with indistinct stipe, about 20 μm high; excipulum up to 400 μm broad, with projecting hairs, up to 1 µm long. Hymenium up to 300 μm high; epihymenium up to 5 μm high, orange-brown, pigment present in the gel and in the walls upper cells of paraphyses, with very gelatinous upper layer. Asci 4–8-spored, ascospores fusiform, 1–3-septate, 25–35 × 6–8 μm.

Sticta flakusiorum is an epiphytic species found in an open area with shrubs at an altitude of 3780 m in the Department La Paz, Bolivia.

The species is named in honor of two lichenologists, Adam Flakus and Pamela Rodriguez-Flakus, for their contributions to the taxonomy of lichens and lichenicolous fungi of Bolivia.

The new species, S. flakusiorum, forms part of the S. humboldtii morphodeme, which also includes S. pseudohumboldtii B. Moncada & Lücking and S. parahumboldtii B. Moncada & Lücking (Moncada et al. 2013b). However, unlike in the other species, the upper surface of S. flakusiorum is rather hirsute, while in S. humboldtii and the other species, the hairs are very dense and resemble the primary tomentum present on the lower surface (Moncada 2012). In addition, S. parahumboldtii has marginal soredia and lacks apothecia (Moncada et al. 2013b). Furthermore, all species differ in the color of the lower surface and tomentum. In the new species, the lower surface is brown, and the primary tomentum is white to cream. Other species have a cream-colored lower surface, and the primary tomentum is cream in S. parahumboldtii, cream-white in S. pseudohumboldtii, and cream to grey-brown in S. humboldtii (Moncada 2012; Moncada et al. 2013b). All species belong to clade I on the Sticta phylogeny (see Fig. 1), but the new species is more closely related to S. viviana. Sticta humboldtii and S. parahumboldtii are related to ‘S. arachnosylvatica’, while S. pseudohumboldtii is close to S. arachnofuliginosa B. Moncada & Lücking (Widhelm et al. 2018). Among the species of this morphodeme, S. humboldtii has been reported more frequently than other species (Moncada 2012; Moncada et al. 2013b), including records from Peru (Ramos 2014). However, only the Colombian records are supported by molecular data (Moncada et al. 2013b, 2014a), and therefore its presence in Peru needs to be verified. Sticta pseudohumboldtii and S. parahumboldtii are known so far only from Colombia (Moncada 2012; Moncada et al. 2013b, 2014a, b).

In the phylogenetic tree, S. flakusiorum forms a lineage sister to a clade of a potentially new species, referred to as Sticta sp. 36 (see above). This taxon is distinguished by its thallus with smooth upper surface, sparse and laminal apothecia, and abundant, marginal phyllidia. Furthermore, the primary tomentum is greyish gold, whereas in S. flakusiorum it is white to brown. The specimens of S. sp. 36 are fragmentary; thus, we have decided not to describe it at this moment. Sticta sp. 36 was found in Peru in Puno (Lampa, Santa Lucia).

The hirsute upper surface is also characteristic of ‘S. arachnosylvatica’, S. minutula B. Moncada, A. Suárez & Lücking and S. hirta (Nyl.) Trevis (Moncada 2012; Moncada et al. 2014a, 2020), but these taxa differ from S. flakusiorum in the structure of the lobes, the presence of vegetative propagules, as well as the color of the lower surface and the structure of primary tomentum. In particular, the lobe margins in all these species are entire to crenate, whereas in S. flakusiorum they are sinusoidal; in addition, ‘S. arachnosylvatica’ and S. minutula have isidia. The lower surface of ‘S. arachnosylvatica’ is cream-white with primary tomentum dense to the margin (Moncada 2012), and in S. minutula the lower surface is cream-white with primary tomentum scarce over the whole area. Additionally, the latter taxon is distinguished by its sparse cyphellae (Moncada 2012). Sticta hirta has a creamy lower surface with irregular tomentum, sparse towards the margins, and it is fasciculate to spongy (Moncada 2012). All three species, ‘S. arachnosylvatica,’ S. minutula, and S. hirta, have been molecularly confirmed only from Colombia (Moncada 2012; Moncada et al. 2014a, 2020) but have not been reported from Bolivia and Peru.

Differing from S. weigelii in lobes with sinuous margins, in the presence of marginal phyllidia, and the scarce, submarginal apothecia, as well as the primary tomentum being light brown to brown, dense, and sparse towards the margins.

Figure 3. 

Morphology of Sticta kukwae (A, B, E holotype C LG3223, D LG3221, F LG3227) A upper surface B lower surface C, D lobes with sinuous margins and marginal phyllidia E lower tomentum with cyphellae and rhizines. Scale bars: 1 mm (A–F).

Bolivia. • Dept. La Paz; Prov. Franz Tamayo, Área Natural de Manejo Integrado Nacional APOLOBAMBA, between la Cumbre and Pelechuco, close to Aguas Blancas, 14°49'12"S, 69°07'05"W, elev. 4070 m, open high Andean vegetation, Altoandino, saxicolous, 15 Nov. 2014, M. Kukwa 14729a (holotype UGDA L-65224, isotype LPB).

Stipe absent. Thallus suborbicular to irregular, up to 10 cm diam., moderately branched, with 3–5 branches per 5 cm radius, branching anisotomous to polytomous; lobes ligulate to flabellate, undulate, with their apices rounded, revolute, and their margins sinuous, not thickened; lobe internodes 5–9 mm long, 4–9 mm broad; thallus coriaceous. Upper surface smooth to shallowly pitted, yellowish brown to brown when dry, shiny; surface glabrous, few lobes with papillae but without maculae; true cilia absent. Only two apothecia found, submarginal, with slightly pronounced invagination on lower side, up to 1.5 mm diam.; disc brown; margin smooth, brown to dark brown. Phyllidia present, marginal and laminal, simple, branched, palmate to corymbose, vertical to obliquely arranged, globular at first, then spatulate to squamiform, usually darker than the thallus. Lower surface uneven, light brown; primary tomentum dense and thick to the margin, sometimes absent at the very edge, fasciculate to spongy, soft, white to brown, sometimes brown with brighter apices; secondary tomentum present, arachnoid. Rhizines present, only on few lobes, whitish to brown, simple to branched, densely distributed. Cyphellae 1–20 per cm² towards the thallus center and 1–20 per cm² towards the margin, dispersed, rounded to irregular, urceolate with wide pore, erumpent to sessile, remaining below the level of the primary tomentum, with the margin elevated and involute, white to beige colored, with tomentum; pore up to 0.5 mm diam.; basal membrane scabrid, white, K+ yellowish, C–, KC–, P–. Medulla compact, white, K–, C–, KC–, P–. No substances detected by TLC.

Upper cortex paraplectenchymatous, up to 65 μm thick, uniform, consisting of up to 7 cell layers with cells 5–10 μm diam., their walls up to 1.5 μm thick. Photobiont layer up to 130 μm thick, its cells up to 15 μm diam. Medulla up to 120 μm thick, its hyphae 4 μm broad, without crystals. Lower cortex paraplectenchymatous, up to 60 thick, with 7 cell layers; cells up to 10 μm diam., their walls up to 2.5 μm thick. Lower primary tomentum up to 400 μm long, with cells resembling secondary tomentum and probably representing thalloconidia, simple or in fascicles formed of up to 20 hyphae, hyphae simple. Lower secondary tomentum 70 mm long, simple to branched, moniliform. Cyphellae cavity up to 150 μm deep; cells of basal membrane without or with single papillae. Apothecia lecanorine (with algal layer below cortex), up to 250 μm high, without distinct stipe; excipulum 150 μm broad, without projecting hairs. Hymenium up to 75 μm high; epihymenium 5 μm high, orange-brown with gelatinous upper layer. Asci immature. Ascospores not observed.

Sticta kukwae is known from Bolivia and Peru. In Bolivia, it was found saxicolous and was collected at a single locality in the Área Natural de Manejo Integrado Nacional Apolobamba in the Department La Paz, at an altitude of 4070 m. In Peru, it was also saxicolous and found in four localities in Puno, in a vegetation type of Roquedal, Matorral de Puna, at an altitude of 3850 m.

Named in honor of the lichenologist Martin Kukwa for his contribution to the taxonomy of lichens and lichenicolous fungi in Bolivia.

Peru. • Puno - Carabaya, Ollachea - Macusani (20 km of Macusani), in a vegetation type of Roquedal, Matorral de Puna, on rocks on the ground/close to the ground, 23 May 2012, N. Magain (LG3225, LG3227, LG3221 & LG3223).

Sticta kukwae is another species in the S. weigelii morphodeme, along with the recently described S. andina B. Moncada, Lücking & Sérus., S. scabrosa, and S. waikamoi Moncada & Lücking. It differs from these species in the type of vegetative propagules and the presence of lobes with strongly sinuous margins, which have not been observed in the other species. Sticta weigelii s.str. and S. waikamoi produce isidia, and S. andina has isidia and phyllidia. Sticta scabrosa, as S. kukwae, produces phyllidia, but in this taxon, they are the same color as the thallus, whereas in the new species, they are blackish-brown. Both species can produce sparse apothecia, but in S. kukwae their margins are crenate and dark brown, whereas in S. scabrosa they are entire to very rarely shallowly crenate and in the same color as the thallus (Moncada et al. 2021b; Ossowska et al. 2022b). Sticta andina may also have apothecia, but they are abundant and with verrucose to crenate margins (Moncada et al. 2021a, b; Ossowska et al. 2022b). Another difference is found in the color of the lower surface, as S. andina has dark lower surface, in S. scabrosa it is yellow-brown, while in S. weigelii the color ranges from beige to dark brown, and in S. waikamoi it is dark brown (Moncada et al. 2020, 2021a, b; Ossowska et al. 2022b). The newly described species has a light brown lower surface. Sticta andina and S. scabrosa have a wide distribution (Moncada et al. 2021a, b; Kaasalainen et al. 2023). In contrast, S. weigelii was previously assumed to be widespread (Galloway 1994, 1997, 2006). However, recent research has shown that its distribution is probably limited to the Neotropics (Moncada et al. 2021b; Mercado-Díaz et al. 2023). All three taxa are also known from Bolivia (Ossowska 2021; Ossowska et al. 2022b). Sticta waikamoi is known from the Hawaiian islands (Moncada et al. 2020, 2021a). Only S. weigelii has been reported from Peru (Ramos 2014), but without molecular evidence.

In the phylogenetic tree (Fig. 1), the new species is closely related to S. umbilicariiformis. However, it has many marginal pustules, which can sometimes make it appear sorediate; thalli is often quite large, and lobes are thick with wavy to foveolate margins. Additionally, the lower surface is cream-colored to brown and thickly tomentose. Sticta umbilicariiformis has been documented in East Africa, with a high probability of its occurrence in other regions as well (Magain and Sérusiaux 2015; Kaasalainen et al. 2023).

The presence of lobes with sinuous margins is also a characteristic feature in the recently distinguished S. monlueckiorum Ossowska, Flakus & Rodr.-Flakus from Bolivia. In S. monlueckiorum, the thallus is larger (up to 10 cm) and moderately branched, while the apothecia are laminal with hirsute margins and without vegetative propagules (Crous et al. 2023), whereas S. flakusiorum has a hirsute upper surface with abundant, submarginal apothecia and without vegetative propagules. All three taxa differ also in the color of the lower surface and the density of the cyphellae. In S. monlueckiorum, the lower surface is beige to yellowish, and the cyphellae have a density of 41–60 per cm² towards the center and more than 100 towards the margins (Crous et al. 2023). In S. flakusiorum, the lower surface is brown, and the cyphellae are 1–20 per cm² towards the center and 41–60 per cm² towards the margins, and in S. kukwae, 1–20 per cm² towards the thallus center and margins.

The hyphae of primary tomentum of Sticta kukwae produce peculiar structures that resemble budding conidia forming chains. Similar structures were found in the isidiate S. atlantica Magain & Sérus., S. fuliginoides Magain & Sérus., and S. fuliginosa by Magain and Sérusiaux (2015), who stated in the case of S. fuliginosa they can act as conidia. These cells in the mentioned species are very similar to cells of secondary tomentum in several Sticta species, and possibly both can play a role of conidia. Such spores thus can be named thalloconidia, which are on the other hand known mainly in several species of the genus Umbilicaria Hoffm. (Hestmark 1990, 1991, 1992), but also in some crustose lichens (e.g., Miriquidica nephaea (Sommerf.) P.F. Cannon, Protoparmelia leproloma (R. Sant.) Rambold & Poelt, Protoparmeliopsis peltata (DC.) Arup, Zhao Xin & Lumbsch, Rhizoplaca melanophthalma (DC.) Leuckert & Poelt, Sporastatia karakorina (Obermayer & Poelt) Davydov & Yakovch.) (Poelt and Obermayer 1990). However, the ultrastructural study of their development must be performed prior to the final change in the conception of their role.