Sticta bicellulata Ossowska, Kukwa, B. Moncada & Luecking, 2022

Ossowska, Emilia Anna, Moncada, Bibiana, Kukwa, Martin, Flakus, Adam, Rodriguez-Flakus, Pamela, Olszewska, Sandra & Luecking, Robert, 2022, New species of Sticta (lichenised Ascomycota, lobarioid Peltigeraceae) from Bolivia suggest a high level of endemism in the Central Andes, MycoKeys 92, pp. 131-160 : 131

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

Fig. 4

Diagnosis.

Differing from S. pseudoimpressula in the predominantly bicellular spores and the absence of secondary tomentum and the K+ violet (instead of carmine-red) reaction of the apothecial atraquinone.

Type.

Bolivia. Dept. La Paz; Prov. Franz Tamayo, Parque Nacional y Área Natural de Manejo Integrado Madidi, near Keara Bajo , 14°41'59"S, 69°04'34"W, elev. 3290 m, open area with shrubs and scattered trees, Ceja de Monte Inferior (Altimontano), on shrubs, 17 Nov 2014, M. Kukwa 14859 (holotype UGDA, isotype LPB) .

Description.

Primary photobiont cyanobacterial ( Nostoc ). Stipe absent. Thallus irregular to suborbicular, up to 10 cm diam., moderately branched, with 3-5 branches per 5 cm radius, branching polytomous; lobes laciniate to flabellate, adjacent, involute to weakly canaliculate, with obtuse to truncate, plane to revolute apices and their margins entire, slightly thickened; lobe internodes (3-)6-8(-20) mm long, (4-)7-10(-13) mm broad; thallus coriaceous. Upper surface pitted to shallowly scrobiculate to rugose, light brown with darker apices in the herbarium, shiny, with the marginal line in the same colour; surface glabrous, without papillae and pruina, without maculae; marginal cilia present, about 0.5 mm, abundant to scarce, white to golden brown, agglutinated. Apothecia scarce, laminal, dispersed, subpedicellate, with pronounced invagination on lower side, up to 2.5 mm diam.; disc orange-brown (in young apothecia) to brown or greenish (in older apothecia) due to the presence of pruina, along the margin with an orange pigment; margin hirsute, with white to golden brown hairs. Vegetative propagules absent. Lower surface uneven, beige to light brown; primary tomentum dense to the margin, thick, but thinner towards the margin, spongy, soft, white to dark brown often with brown tips; secondary tomentum absent. Rhizines absent. Cyphellae 1-10 per cm2 towards the thallus centre and 21-40 per cm2 towards the margin, abundant, scattered, rounded to irregular, urceolate with wide pore, prominent, remaining below the level of the primary tomentum, with the margin raised and involute, white to brown coloured, without or with tomentum at the base; pore (0.25-)0.5-1(-1.5) mm diam.; basal membrane pruinose in the appearance, white, K- to K+ yellow, C-, KC-, Pd-. Medulla compact, white with yellow spots, K+ pale yellow, C-, KC-, Pd-. Apothecial margin (ring around disc) and epihymenium K+ violet. No substances detected by TLC in the thallus, unidentified anthraquinone in the apothecia.

Upper cortex paraplectenchymatous, 35-50 μm thick, consisting of 3-4 layers of cells 5-16 μm diam. (with smaller cells in outside parts of the cortex), their walls 1.5-3.5 μm thick and their lumina rounded to isodiametric, 4-15 μm diam. Photobiont layer 40-80 μm thick, its cells 5-10 μm diam. Medulla 35-50 μm thick, its hyphae 5 μm broad, without crystals. Lower cortex paraplectenchymatous, 25-35 μm thick, with 2-3 cell layers; cells 7-13 μm diam., their walls 2.5-5 μm thick. Hairs of lower primary tomentum 100-250 μm long, in fascicles of more than 20 when mature, simple to rarely branched hyphae, 5-6 μm broad, septate with free apices. Cyphella cavity up to 100 μm deep; cells of basal membrane loosely packed consisting of cells, without papillae or very rarely, with one papillae. Apothecia biatorine, up to 100-250 μm high, without a peduncle; excipulum 80-100 μm broad, laterally with projecting hairs, hairs simple, up to 110 μm long or in groups up to 300 μm long, hairs 4-6 μm broad, thick-walled, septate. Hymenium 100-112 μm high; epihymenium 12.5-20 μm high, orange-brown, with orange granules crystals, with thin gelatinous upper layer. Asci 6-8-spored, ascospores broadly fusiform, 1(-3)-septate, 30-41 × 9-12 μm.

Habitat and distribution.

The species is known from the Parque Nacional y Área Natural de Manejo Integrado Madidi, a protected area in the Department La Paz. It was found epiphytic at an elevation of 3290 m.

Etymology.

The epithet refers to the predominance of bicellular spores.

Additional material examined.

Bolivia. Dept. La Paz; Prov. Franz Tamayo, Parque Nacional y Área Natural de Manejo Integrado Madidi, near Keara Bajo , 14°41'59"S, 69°04'34"W, elev. 3290 m, open area with shrubs and scattered trees, Ceja de Monte Inferior (Altimontano), on shrubs, 17 Nov 2014, M. Kukwa 14863 (LPB, UGDA) .

Notes.

Sticta bicellulata is similar to S. pseudoimpressula (another species described below), but the main discriminating character in S. bicellulata is the septation of the ascospores, which are predominantly bicellular (only very few are 3-septate whereas in S. pseudoimpressula , only young ascospores are bicellular. Both taxa have irregular to suborbicular thalli, with laciniate to flabellate lobes, but the lobe apices in S. bicellulata are obtuse to truncate vs. orbicular in S. pseudoimpressula . Furthermore, S. bicellulata has a paler upper surface than S. pseudoimpressula . In both species, marginal cilia are present, but in S. bicellulata , they are agglutinated, white to golden brown vs. fasciculated, light brown to golden brown in S. pseudoimpressula . Apothecia in S. bicellulata are sparse in contrast to the abundant apothecia in S. pseudoimpressula . They also differ in the colour of the disc, which in both species is covered by a pruina. The margin and epihymenium react with K in both taxa, but in S. bicellulata the reaction is K+ violet and in S. pseudoimpressula K+ carmine-red, suggesting the presence of different anthraquinones. The lower surface in both species is uneven, but in S. bicellulata , the tomentum is thick, becoming thinner towards the margin and a secondary tomentum is absent. Conversely, in S. pseudoimpressula , the primary tomentum is consistently thick and long, with a secondary tomentum present and with rhizines. The cyphellae in these two taxa are similar in shape, but in S. bicellulata , their margins are raised and involuted.

Remarkably, the taxa form a sister group relationship, denoting the presence of apothecial anthraquinones as a synapormorphy, although apparently, the two species diverged to the point that the anthraquinones are of a different nature, as indicated by their different K+ reaction. This character appears to be rare in Sticta , but may also have been overlooked, as it is only obvious in a close-up of the apothecium.

The clade formed by Sticta bicellulata and S. pseudoimpressula is closely related to S. sylvatica and S. peltigerella (Fig. 1 ; Suppl. material 3: Fig. S1). The latter two produce numerous isidia distributed over the entire surface of the thalli ( Moncada 2012). Sticta sylvatica is widespread, occurring in Europe, North and South America ( Hodkinson et al. 2014), whereas S. peltigerella appears to be a Colombian endemic ( Moncada 2012).

Figures

Figure 1. Best-scoring Maximum Likelihood tree of the Sticta clades I-III containing the new species from Bolivia (blue) and Colombia (orange), based on the fungal ITS barcoding marker. Supported clades are thickened. For a complete tree with individual support values, see Suppl. material 3: Fig. S 1.

Figure 4. Morphology of Sticta bicellulata (holotype) A enlarged part of thallus showing pitted to rugose upper surface and laminal apothecia B lower surface C enlarged part of lower surface of the thallus D apothecia with hirsute margins and cilia at the lobe margins E tomentum and cyphellae F ascus with 1 - septate ascospores. Scale bars: 1 mm (A-E); 10 μm (F).