Sticta flakusiorum Ossowska, B. Moncada & Lucking 2025, sp. nov.
Creators: name: Ossowska, Emilia Anna
name: Moncada, Bibiana
name: Lücking, Robert
name: Sérusiaux, Emmanuel
name: Magain, Nicolas
Publisher: name: Zenodo
Year: 2025
Subjects: Biodiversity
Taxonomy
Fungi
Ascomycota
Lecanoromycetes
Peltigerales
Peltigeraceae
Sticta
Sticta flakusiorum

description: Sticta flakusiorum Ossowska, B. Moncada & Lücking sp. nov.
Fig. 2
Diagnosis.
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.
Type.
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).
Description.
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 cm 2 towards the thallus center and 41–60 per cm 2 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.
Habitat and distribution.
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.
Etymology.
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.
Notes.
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. 2013 b). 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. 2013 b). 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. 2013 b). 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. 2013 b), including records from Peru (Ramos 2014). However, only the Colombian records are supported by molecular data (Moncada et al. 2013 b, 2014 a), 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. 2013 b, 2014 a, 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. 2014 a, 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. 2014 a, 2020) but have not been reported from Bolivia and Peru.
description: Published as part of Ossowska, Emilia Anna, Moncada, Bibiana, Lücking, Robert, Sérusiaux, Emmanuel & Magain, Nicolas, 2025, Sticta flakusiorum and S. kukwae — two additional new species from the Neotropics (Peltigerales, Peltigeraceae), pp. 259-276 in MycoKeys 114 on pages 259-276, DOI: 10.3897/mycokeys.114.139681