Sticta rubropruinosa Moncada & Lücking, 2012

Moncada, Bibiana & Lücking, Robert, 2012, Ten new species of Sticta and counting: Colombia as a hot spot for unrecognized diversification in a conspicuous macrolichen genus, Phytotaxa 74 (1), pp. 1-29 : 20-21

Sticta rubropruinosa Moncada & Lücking , spec. nov. ( Fig. 8 )

MycoBank #801850

Differing from Sticta granatensis and similar species in the red, K+ green pruina on the thallus and cyphellae, visible as minute, scattered dots.

Holotype: — COLOMBIA. Antioquia: Mun. Frontino, Nutibara, cuenca alta del Rio Cuevas ; 1780 m; 23 Sep 1987, Sanchez et al. 1621 ( COL).

Primary photobiont green ( Dictyochloropsis ). Stipe absent. Thallus irregular, up to 20 cm diam., moderately branched, with 3–5 branches per 5 cm radius, branching polytomous to pleurotomous; lobes flabellate, horizontal to subpendulous, interspaced to adjacent, plane, their apices obtuse to truncated, plane, their margins entire, not thickened; lobe internodes (5–)6–12(–20) mm long, (2–)6–7(–10) mm broad; thallus subcoriaceous. Upper surface foveolate to apically faveolate, grass green when fresh, red-brown and apically darker in the herbarium, shiny; surface glabrous, without papillae, with scattered, tiny, often indistinct red spots, and with irregular, yellowish white maculae; marginal cilia abundant, agglutinate to squarrose, brown to blackish, up to 0.7 mm long. Apothecia not observed. Vegetative propagules absent. Lower surface uneven, cream-colored to yellowish; primary tomentum dense but sparse towards the margin, thick, thinner towards the margin, spongy to arachnoid, soft, golden brown; secondary tomentum absent. Rhizines absent. Cyphellae 41–60 per cm 2 towards the thallus center and margin, scattered, rounded, urceolate with wide pore, immersed to erumpent, remaining below the level of the primary tomentum, with the margin revolute, cream-colored to yellowish, with scattered red dots, without tomentum; pore (0.2–)0.5–1.2(–2) mm diam.; basal membrane pubescent and partially red-pruinose, otherwise cream-colored, K + emerald-green where red-pruinose (isohypocrelline), C –, KC–, P –. Medulla compact, pale yellow, K –, C –, KC–, P –. No substances detected by TLC.

Upper cortex paraplectenchymatous, 25–35 µm thick, forming two different layers: upper layer consisting of 1–2 cell layers with cells 4–6 µ m diam., their walls 2.5–3.5 µ m thick and their lumina rounded to isodiametric, 1.2–2.5 µm diam.; lower layer consisting of 2–3 cell layers; cells 4–11 µm diam., their walls 1–1.5 µm thick and their lumina rounded to isodiametric, 3–9 µm diam. Photobiont layer 20–25 µm thick, its cells 5–7 µm diam. Medulla 70–115 µm thick, its hyphae 2.5 µm broad, without crystals. Lower cortex paraplectenchymatous, 18–35 µm thick, with 2–3 cell layers; cells 6–14 µm diam., their walls 1.5–3.5 µm thick. Hairs of lower primary tomentum 30–800 µm long, in fascicles of 6–12, branched hyphae, septate with their apices intertwined. Cyphellae cavity 90–110 µm deep; cells of basal membrane without papillae.

Distribution and Ecology: —South American Andes ( Colombia), known only from the type found at 1780 m altitude in subandine forest of the western slope of the Cordillera Occidental, in a moderately exposed microhabitat. The species grows on bark and was found associated with bryophytes of the genera Omphalantus and Calypogeia Raddi (1818) .

Etymology: —The name refers to the scattered red pruina on the thallus and cyphellae.

Remarks: — Sticta rubropruinosa is one of a number of species with a thallus morphology resembling that of Lobaria pulmonaria (L.) Hoffm., i.e. with green lobes with faveolate surface. It is most similar to S. granatensis Nyl. ( Nylander 1874) , but differs from these and other species with this morphology by the scattered, red dots on the thallus surface and margin of the cyphellae, consisting of the pigment isohypocrelline, identified by its K+ emerald-green to yellow-green reaction under the microscope. Unfortunately, the pigment concentration in the thallus was found to be too low to show up in TLC. Isohypocrelline latter is comparatively rare in lichens and thus far only known from the families Graphidaceae and Trypetheliaceae ( Mathey et al. 1994; Staiger 2002). This is the first time that this pigment is reported for the Peltigerales or any of the known macrolichen genera in the Lecanoromycetes.

Figures

FIGURE 8. Sticta rubropruinosa (holotype collection). A. Upper side of thallus. B. Lower side of thallus. C. Upper surface enlarged. D. Detail of upper surface showing red patches. E–G. Detail of lower tomentum and cyphellae towards thallus center and towards lobe apices. G. Cyphella enlarged showing margin with red spots and K+ emerald-green reaction. H. Microscopic section through thallus and cyphella, showing red pruina on upper surface. Scale in A and B = 10 mm, in C–F = 1 mm, in G = 0.5 mm, in H = 50 µm.