Sticta arbuscula 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 : 7-9

Sticta arbuscula Moncada & Lücking , spec. nov. ( Fig. 2 )

MycoBank #801844

Differing from Sticta fuliginosa in the mostly marginal, arbuscular isidia and the scabrous to pubescent upper lobe surface.

Holotype: — COLOMBIA. Cundinamarca: Mun. La Calera, Parque Nacional Natural Chingaza, Monterredondo ; 4° 44' N 73° 51' O, 3430 m; 13 Apr 2011, Moncada 4627 ( UDBC; isotype: F).

Primary photobiont cyanobacterial ( Nostoc ). Stipe absent. Thallus orbicular to irregular in outline, up to 10 cm diam., sparsely branched, with 0–2 branches per 5 cm radius, branching anisotomous; lobes suborbicular, horizontal to ascending, adjacent to imbricate, plane to involute, with their apices rounded to irregular in outline, involute, and their margins entire to crenate, not thickened; lobe internodes (4–)5–15(–20) mm long, (3–)4–8(–12) mm broad; thallus subcoriaceous, fragile. Upper surface smooth to weakly foveolate, dark green when fresh, brownish grey with pale brown margin in the herbarium, matt; surface pubescent to scabrous, without papillae and pruina, but with irregular, scattered, white maculae; marginal cilia absent. Apothecia sparse, predominantly submarginal, dispersed, subpedicellate, with pronounced invagination on lower side, up to 2 mm diam.; disc orange-red, shiny; margin entire to weakly crenate, cream-colored. Isidia abundant, predominantly marginal but also laminal, aggregate, branched, arbuscular with conspicuous basal stalk, vertically to obliquely oriented, up to 1 mm long and 0.2 mm broad, darker than the thallus to blacking brown, shiny, cylindrical; basal stalk cylindrical, with cyphellae. Lower surface smooth to uneven, creamcolored; primary tomentum irregular, absent towards the margin, thick, fasciculate to spongy, soft, pale to dark brown-grey; secondary tomentum pubescent, pale. Rhizines absent. Cyphellae 1–20 per cm 2 towards the thallus center and 21–40 per cm 2 towards the margin, scattered, round to irregular in outline, cupuliform to urceolate with wide pore, immersed to prominent, remaining below the level of the primary tomentum, with the margin thin to weakly involute, white to cream-colored, covered with secondary tomentum; pore up to (0.5–)0.8–2.5(–3.5) mm diam.; basal membrane pubescent, white, K – to K + pale yellow, C –, KC+ pale yellow, P –. Medulla lax to compact, white, K + pale yellow to ochraceous, C –, KC+ pale yellow, P –. No substances detected by TLC.

Upper cortex paraplectenchymatous, 20–30 µm thick, uniform, consisting of 2–3 cell layers with cells 6–11 µm diam., their walls 1.5–3.5 µm thick and their lumina rounded to isodiametric, 4–8 µm diam. Photobiont layer 35–55 µm thick, its cells 12–18 µm diam. Medulla 55–125 µm thick, its hyphae 2.5 µm broad, without crystals. Lower cortex paraplectenchymatous, 20–40 µm thick, with 3–4 cell layers; cells 6.5–14 µ m diam., their walls 1.2–1.5 µ m thick. Hairs of upper tomentum 2.5–5 µ m long, of single, unbranched, moniliform hyphae with free apices. Hairs of lower primary tomentum 1220–1370 µm long, in fascicles of more than 20, branched hyphae with free, moniliform apices. Hairs of lower secondary tomentum 10–28 µm long, of single, branched, moniliform hyphae with free apices. Cyphellae cavity 75–140 µm deep; cells of basal membrane with numerous papillae. Apothecia biatorine, 560–680 µm high, without stipe; excipulum 100–125 µm broad. Hymenium 125–150 µm high; epihymenium 2.5–5 µm high, orange, without gelatinous upper layer. Ascospores not observed.

Distribution and Ecology: —South American Andes ( Colombia and Ecuador). Sticta arbuscula has been found between 3000 and 3700 m altitude, in subandine high altitude forests and in the páramo region, usually in exposed microhabitats on bark (twigs and stems of shrubs and treelets). The species is usually associated with bryophytes of the genera Plagiochila , Metzgeria , Jubula Dumort. ( Dumortier 1822) , and Omphalanthus Lindenb. & Nees ( Gottsche et al. 1845), as well as Lejeuneaceae .

Etymology: —The epithet refers to the conspicuous, arbuscular isidia, that is, branched isidia with a distinct, persistent basal stalk.

Remarks: — Sticta arbuscula is superficially similar to S. fuliginosa due to the broad, rounded, sparsely branched, isidiate lobes, but differs in the isidia being arbuscular, predominantly marginal, large and conspicuous, and also in the pubescent to scabrous upper surface. Also, the number of papillae found on the cells of the basal membrane of the cyphellae is higher than in S. fuliginosa ( Suárez & Lücking 2012) . Marginal isidia are also found in S. weigelii (Ach.) Vain. ( Vainio 1890) and its relatives ( McDonald et al. 2003; Galloway 2006); however, these species have larger, more robust thalli with irregular to linear lobes and the isidia are not arbuscular. Also, the lower tomentum in these species is usually dark.

Additional specimens examined (paratypes): — COLOMBIA. Antioquia: Mun. Medellín ,

Corregimiento San Félix; 6° 21' N, 75° 41' E; 3000 m; 8 Jul 1986, Sipman et al. 34230 ( B, HUA). Cauca :

Mun. Puracé, Costado Oriental, road from La Plata to Puracé , 2 km east of San Juan hot springs; 3000 m; 4 Oct 1984, Aguirre & Sipman 5866 ( B, COL) . Parque Nacional Natural Puracé, Pilimbalá, Laguna de San Rafael ; 3300 m; 6 Oct 1984, Aguirre & Sipman 5977 ( B, COL) . Pilimbalá, Volcán Puracé ; 3390 m; 19 Mar 2000, Moncada & Dávila 582 ( UDBC) ; ibid.; 3560 m; 19 Mar 2000, Moncada & Dávila 606 ( UDBC) . ibid.; 3700 m; 19 Mar 2000, Moncada & Dávila 613 ( UDBC) . Cundinamarca: Mun. Choachí, El Verjón, PE Matarredonda ; 4º 33' N, 74º 00' E; 3220 m; 23 Jan 2011, Moncada 4595 ( UDBC) . Mun. Guasca, Páramo de Guasca ; 3350 m; 18 Aug 2011, Moncada 4736, 4749, 4750 ( UDBC) ; ibid.; 3200 m; 18 Aug 2011, Lücking 33324 ( F, UDBC) . Zona de Amortiguación Parque Nacional Natural Chingaza, Vía del Ángulo towards Rincón del Oso ; 3600 m; 7 Nov 2011, Moncada 4922, 4983 ( UDBC) .

ECUADOR. Napo: Páramo de Papallacta ; 3300 m, Moncada 13b ( F) .

Figures

FIGURE 2. Sticta arbuscula (holotype collection). A. Thallus. B. Lower surface. C. Upper surface enlarged. D. Lower surface enlarged. E. Laminal isidia enlarged. F. Marginal isidia enlarged. G. Microscopic section through cyphella. H. Microscopic section through cyphella enlarged, showing basal membrane with papillose cells. Scale in A and B = 10 mm, in C and D = 5 mm, in E = 1 mm, in F = 0.5 mm, in G = 50 µm, in H = 10 µm.