Sticta isidiolobulata Ossowska, B. Moncada, Luecking & Kukwa, 2024

Ossowska, Emilia Anna, Moncada, Bibiana, Luecking, Robert, Flakus, Adam, Rodriguez-Flakus, Pamela, Olszewska, Sandra & Kukwa, Martin, 2024, Additional new species and new records of the genus Sticta (lichenised Ascomycota, lobarioid Peltigeraceae) from Bolivia, MycoKeys 105, pp. 21-47 : 21

Sticta isidiolobulata Ossowska, B. Moncada, Luecking & Kukwa sp. nov.

Fig. 2

Diagnosis.

Differing from S. impressula in the presence of isidia developing into spathulate lobules and apothecia with entire to weakly-crenate margins and the presence of sparse, secondary tomentum.

Type.

Bolivia. Dept. Cochabamba; Prov. Carrasco, Parque Nacional Carrasco, between Meruvia and Monte Punku, 17°34'43"S, 65°15'25"W, elev. 3082 m, Podocarpus forest, Ceja de Monte Inferior (Altimontano), corticolous, 26 Nov. 2014, M. Kukwa 15054 (holotype UGDA, isotype LPB) .

Description.

Primary photobiont cyanobacterial ( Nostoc ). Stipe absent. Thallus irregular to suborbicular, subcoriaceous, up to 15 cm diam., moderately branched, with 3-5 branches per 5 cm radius, branching polytomous to anisotomic; lobes ligulate to flabellate, adjacent, plane to involute, with their apices rounded and involute and their margins entire to crenate and not thickened; lobe internodes (2-)3-5(-7) mm long, (3-)6-8(-10) mm broad. Upper surface pitted to rugose-foveolate towards the centre, beige brown with slightly darker apices when dry, shiny; surface glabrous, without papillae and pruina, with orbicular to irregular, scattered, pale beige maculae; marginal cilia absent, but extension of the lower tomentum visible. Apothecia abundant, mostly laminal or submarginal, dispersed or rarely grouped in four, subpedicellate to pedicellate, without pronounced invagination on lower side, up to 2.5 mm diam.; disc orange-brown or yellow (in young apothecia), shiny, concave in young apothecia, convex in older; margin entire to weakly crenate, light brown, not visible from surface view in mature apothecia. Vegetative propagules in the form of flattened and branched isidia developing especially on margins into spathulate lobules, aggregate, branched, horizontal, up to 0.25 mm long and 0.5 mm broad, darker than the thallus, brown grey, shiny. Lower surface undulate and veined, beige to light brown towards the centre; primary tomentum dense, but absent towards the margin, thick, but thinner towards the margin, spongy to fasciculate, soft, beige to brown in older parts; secondary tomentum present, pubescent, sparse. Rhizines absent. Cyphellae 1-20 per cm2 towards the thallus centre and 21-40 per cm2 towards the margin, scattered, rounded or elongated, urceolate with wide pore to cupuliform, prominent, remaining below the level of the primary tomentum, with the margin erect to raised and involute, cream to brown coloured, with tomentum; pore (0.25-)0.5-0.7 mm diam.; basal membrane scabrid, white. Medulla compact, white. Pycnidia present, immersed.

Upper cortex paraplectenchymatous, 30-75 μm thick, differentiated into two cellular layers with the upper layer consisting of 1-2 cell layers, cells 4.5-12 × 4.5-7 μm, their walls 1-3.5 μm thick and their lumina rounded to elongated, 4-11 × 3-6 μm. Photobiont layer 25-55 μm thick, its cells 5-10 μm diam. Medulla 50-150 μm thick, its hyphae 2-4 μm broad, without crystals. Lower cortex paraplectenchymatous, 30-60 μm thick, of 2-4 cell layers; cells 6-15 × 6-12 μm diam., their walls 1-3 μm thick. Hairs of lower primary tomentum up to 400 μm long, in fascicles more than 20, hyphae unbranched, septate with free apices; hairs of secondary tomentum 10-18 μm long, 5-6 μm broad, consisting of two 2-4 cells. Cyphellae cavity up to 250 μm deep; cells of basal membrane with many small papillae (up to 0.5 μm high). Apothecia biatorine, up to 500 μm high, without or with distinct stipe; excipulum up to 130 μm broad, without hairs. Hymenium up to 130 μm high; epihymenium 2.5-5 μm high, yellowish, without gelatinous upper layer; epihymenium pale brown-orange. Asci 4-8-spored, ascospores fusiform, 1(-3)-septate, 25-35 × 6-8 μm.

Secondary chemistry.

No lichen substances detected by TLC. All parts of thallus and apothecia K-, C-, KC-, P-.

Habitat and distribution.

Sticta isidiolobulata is known only from the type locality in the Parque Nacional Carrasco in the Cochabamba Department. It was found on tree bark in Podocarpus forest.

Etymology.

The epithet refers to the presence of isidia that develop into spathulate lobules, especially at the lobe margins.

Notes.

Sticta isidiolobulata is another morph within the S. impressula morphodeme, like S. pseudoimpressula and the undescribed ' S. isidioimpressula ' ( Moncada 2012; Ossowska et al. 2022a). However, the new species is the only one in this group characterised by the presence of both vegetative propagules and apothecia, isidia developing into spathulate lobules, without true cilia and with beige to brown primary tomentum, which is dense, but absent at the margins. Sticta pseudoimpressula lacks vegetative propagules, the tomentum is greyish-brown to black and dense at the margins ( Ossowska et al. 2022a). In contrast, ' S. isidioimpressula ' produces laminal, white to grey, cylindrical isidia, instead of marginal, greyish-green and spathulate lobules observed in S. isidiolobulata . Furthermore, the primary tomentum in S. isidioimpressula is dense and sparse towards the margins and without secondary tomentum ( Moncada 2012).

The presence of propagules in the form of isidia and lobules is also characteristic of S. macrofuliginosa B. Moncada & Lücking from Colombia ( Moncada et al. 2015) and S. parvilobata Merc.- Díaz from Puerto Rico ( Mercado-Díaz et al. 2020). However, in S. macrofuliginosa , isidia are cylindrical, whereas in S. parvilobata , they are granular to globular. In contrast, the lobules in both species are lobuliform. These taxa also differ from S. isidiolobulata in the upper surface of the thallus, which is scrobiculate to foveolate with sparse laminal apothecia in the Colombian species and smooth to scrobiculate without apothecia in the Puerto Rican species. In addition, the primary tomentum is dense to the lobe margins and spongy in S. macrofuliginosa and sparse, but sometimes dense and hirsute to fasciculate in S. parvilobata ( Moncada 2012; Moncada et al. 2015; Mercado-Díaz et al. 2020).

The new species is related to the Colombian ' S. pseudosylvatica ' (Fig. 1 ), which still awaits formal validation. Both taxa differ in the structure of the upper surface, which is smooth to ribbed in ' S. pseudosylvatica ' and pitted to rugose in S. isidiolobulata . Furthermore, ' S. pseudosylvatica ' has abundant, laminal isidia and primary tomentum is dense to the margins ( Moncada 2012). The abundance of cyphellae also varies between them and, in ' S. pseudosylvatica ', they occur in amounts of 21-40 per cm2 towards the centre and 61-100 per cm2 towards the margins, while in the new species, there are 1-20 per cm2 and 21-40 per cm2, respectively ( Moncada 2012).

Figures

Figure 1. Best-scoring Maximum Likelihood tree of the Sticta target clade containing the new species from Bolivia (red) and the species new to Bolivia and phylogenetically confirmed from Bolivia (blue), based on the fungal ITS barcoding marker. Supported clades are thickened. For complete tree with individual support values, see Suppl. material 2.

Figure 2. Morphology of Sticta isidiolobulata (holotype) A upper surface B lower surface C lower tomentum with cyphellae D, E Isidia developing into spathulate lobules and apothecia F section of apothecium. Scale bars: 1 mm (A-D, F, G); 0.5 mm (E); 50 μm (F).