Cora arachnoidea J. E. Hern. & Lücking, 2013

Lücking, Robert, Dal-Forno, Manuela, Lawrey, James D., Bungartz, Frank, Holgado Rojas, María E., Hernández, Jesús E., Marcelli, Marcelo P., Moncada, Bibiana, Morales, Eduardo A., Nelsen, Matthew P., Paz, Elias, Salcedo, Luis, Spielmann, Adriano A., Wilk, Karina, Will-Wolf, Susan & Yánez-Ayabaca, Alba, 2013, Ten new species of lichenized Basidiomycota in the genera Dictyonema and Cora (Agaricales: Hygrophoraceae), with a key to all accepted genera and species in the Dictyonema clade, Phytotaxa 139 (1), pp. 1-38 : 6-8

Cora arachnoidea J. E. Hern. & Lücking , sp. nov. ( Fig. 3 )

Mycobank #805376

Genbank ITS barcoding sequence: KF443233

Differing from the morphologically similar and closely related Cora hirsuta in the larger thallus and lobes with brown color when fresh and the shorter, arachnoid tomentum on the upper surface.

Holotype: — VENEZUELA. Mérida: Parque Nacional Sierra Nevada, surroundings of Laguna de Mucubají ; 8º 47' N, 70º 49' W, 3626 m; 6 December 2009, Hernández 1780 ( VEN).

Thallus terricolous between bryophytes, rarely epiphytic on bryophyte-laden branches, foliose, up to 10 cm across, composed of 5–10 semicircular lobes per thallus; lobes 1–3(–5) cm wide and 1–5(–7) cm long, unbranched or once branched but lacking radial branching sutures, greyish brown to brown with slight concentric color zonation when fresh, with thickened, involute, white margins, becoming pale yellowish grey in the herbarium. Upper surface densely and shortly arachnoid-hirsute over entire surface (barely visible when fresh); trichomes densely interwoven basally but apically free and irregularly arranged, 0.2–0.3 mm long and 25–50 µm thick at the base, composed of loosely agglutinated hyphae; involute margin with underside very minutely arachnoid; lower surface ecorticate, finely felty-arachnoid (representing the exposed medulla), white when fresh and becoming yellowish white in the herbarium. Thallus in section 250–350 µm thick, with upper cortex, photobiont layer, and medulla; upper cortex formed by a 25–50 µm thick layer of rather loosely packed, periclinal, 4–5 µm thick hyphae supported by a 20–30 µm high 'medullary' layer of spaced groups of densely packed, anticlinal, 3–5 µm thick hyphae; photobiont layer 50–150 µm thick, irregular, composed of clusters of short, coiled cyanobacterial filaments wrapped in a dense, paraplectenchymatous hyphal sheath formed by jigsaw puzzle-shaped cells, clusters 20–30 µm diam., individual photobiont cells 10–12 µm broad and 6–8 µm long, dark blue-green to yellow-green in upper portions, penetrated by tubular fungal hyphae; heterocytes sparse, hyaline to pale yellow, 8–10 µm wide and 5–6 µm long; cells of hyphal sheath wavy in lateral outline, 3–4 µm thick; medulla 50–100 µm thick, composed of loosely woven, irregularly arranged to more or less periclinal hyphae 4–5 µm thick; clamp connections not observed.

Hymenophore developed as irregular to angular or elongate, resupinate patches dispersed on the underside, patches 3–10 mm diam., with pale yellow, smooth surface and byssoid margins; hymenophore in section 50–100 µm thick, composed of a paraplectenchymatous layer resting on loose, 4–6 µm thick, generative medullary hyphae and supporting the hymenium; hymenium composed of numerous, palisade-like basidioles and scattered basidia; basidioles 20–30 × 5–6 µm; basidia 25–35 × 5–7 µm, 4-sterigmate; basidiospores (few seen) ellipsoid, non-septate, hyaline, 7–8 × 2.5–3.5 µm.

Chemistry: no substances detected by TLC.

Distribution and Ecology: —This species is known from several collections from Costa Rica, Colombia, Venezuela, and Bolivia; it is probably widespread in the northern Andes and the Costa Rican Cordilleras. It is a typical paramo species, mostly growing on soil between bryophytes in exposed situations.

Etymology: —The epithet refers to the arachnoid tomentum on the upper surface.

Remarks: — Cora arachnoidea is the second species known with a tomentose surface, after Cora hirsuta (Moncada & Lücking) Moncada & Lücking , comb. nov. [Mycobank #805388; bas.: Dictyonema hirsutum Moncada & Lücking in Lumbsch et al., Phytotaxa 18: 48 (2011); holotype: Colombia, Lücking 25900 (UDBC; isotype: F!)]. The latter differs from C. arachnoidea in the smaller thallus and lobes furnished with a much thicker tomentum easily visible even when hydrated, and a zonate margin with an olive-green, glabrous, submarginal zone and a white, tomentose margin ( Lumbsch et al. 2011). Cora arachnoidea is a good example how markedly specimens can differ in the living, hydrated stage compared to rather non-descript herbarium material, a possible explanation why this genus has been a stumbling block for lichenologists and mycologists in the past and only a single species has been recognized by most authors ( Parmasto 1978; Hawksworth 1988; Oberwinkler 2001). Field images are practically indispensable for correct identifications in this genus.

Additional specimens examined: — MEXICO. Jalisco: Parque Nacional Volcán Nevado de Colima, beyond entrance station in La Joya area near the campground; 19° 35' N, 103° 36' W, 3415 m; 26 December 2006, Egan 17538 ( OMA) . COSTA RICA. Sán José: Los Santos Forest Reserve, Cerro de la Muerte ( Pacífico Central Conservation Area ), Talamanca Ridge, km 90 on road (ruta 2) from Cartago to San Isidro , access road to towers on summit; 83° 45' W, 9° 34' N, 3400–3500 m; upper montane cloud forest and subalpine paramo zone, disturbed low paramo shrub with Chusquea , on bryophyte, exposed; September 2007, Lücking R18 (F) . COLOMBIA. Cundinamarca: Páramo de Sumapaz, Laguna de Chizacá ; 4° 17' N, 74° 12' W, 3700–3750 m; wet paramo with Espeletia ; August 2010, Lücking 32700 (F, UDBC) . VENEZUELA. Venezuela. Mérida: Parque Nacional Sierra Nevada, surroundings of Laguna de Mucubají ; 8º 47' N, 70º 49' W, 3626 m; 6 December 2009, Hernández 1779, 1782 ( VEN) . BOLIVIA. Santa Cruz: Caballero, Siberia region near La Palma; 17° 49' S, 64° 40' W, 2582 m; Yungas cloud forest, epiphytic on bark; 12 December 2004, Wilk 2780a ( KRAM) .

Figures

FIGURE 3. Cora arachnoidea. A. Specimen in the field (Colombia, Lücking 32700). B. Lobe enlarged showing tomentose upper surface (holotype). C. Lobe underside showing hymenophore with involute, byssoid margins (Venezuela, Hernández 1782). Scale in A, C = 5 mm, in B = 1 mm.