Lecanactis minuta Ertz, Flakus & Kukwa 2015, sp. nov.
Creators: name: Ertz, Damien
name: Flakus, Adam
name: Oset, Magdalena
name: Sipman, Harrie J. M.
name: Kukwa, Martin
Publisher: name: Zenodo
Year: 2015
Subjects: Biodiversity
Taxonomy
Fungi
Ascomycota
Arthoniomycetes
Arthoniales
Roccellaceae
Lecanactis
Lecanactis minuta

description: Lecanactis minuta Ertz, Flakus & Kukwa sp. nov. (Fig. 5) MycoBank no. MB 812517   
 Diagnosis: Similar to Lecanactis salicina but with distinct white apothecial margin contrasting with a pale brownish apothecial disc.   
 Type: — BOLIVIA. Dept. La Paz: Prov. Franz Tamayo, near Yuyo, 1150 m, 15°07’05”S, 68°20’22”W, Preandean Amazon forest, on bark, 16 May 2011, M. Kukwa 8710 (holotype UGDA!, isotypes BR!, LPB!).   
 Thallus epiphloeodal, ecorticate, thin, c. 30–90 μm thick, continuous, pale grayish to pale brown, matt; prothallus not seen; photobiont trentepohlioid; cells 10–14 × 7–9 μm; apothecia sessile, with constricted base, scattered, rounded, rarely slightly elongated, rarely with an undulate margin, 0.4–0.6 mm diam.; margin covered by a thick layer of white pruina, shining due to crystals; disc flat to slightly convex, covered by a grayish to pale brown pruina; exciple brownblack, K+ slightly olivaceous, thicker at the base of the apothecium, basally 65–100 μm thick, laterally 20–50 μm thick and covered by a thin (c. 25 μm) layer of thallus; hymenium 100–130 μm tall, hyaline, not inspersed, I+ red, K/I+ blue-violet; epihymenium hyaline to pale brown, I+ persistently blue-violet, K/I+ blue-violet covered with numerous crystals (at least some of calcium oxalate); hypothecium 10–28 μm tall, pale brown, I+ blue-violet turning red, K/I+ blue-violet, K+ slightly olivaceous; paraphyses branched, anastomosing, 1–1.5 μm thick, not or only slightly enlarged at apices; asci clavate, 65–70 × 14–16 μm, 8-spored, in K/I non-amyloid except for a blue endoascus layer in the upper part, and a blue apical ring around a small ocular chamber; ascospores 24–30 × 4–4.5 μm, 3(–4)-septate, not constricted at septa, cells more or less equal in size, becoming pale brown when overmature; gelatinous sheath absent or not evident (at ×1000); pycnidia not seen.   
 Chemistry: thallus K–, C–, P–, UV– (apothecia appearing darker than the thallus); substances detected by TLC (holotype tested): roccellic acid, 3 unknown substances, UV+ blue-violet before heating (Rf 60 in solvent G), UV+ violet after heating (Rf 82 in solvent G) and UV+ orange substance after heating (Rf 90 in solvent G, probably a terpenoid).   
 Etymology: The name refers to the tiny ascomata.   
 Distribution and habitat: So far L. minuta is only known from the type locality.   
 Notes: The new species fits well the genus Lecanactis Eschw. by its ecorticate thallus, sessile apothecia with a carbonized excipulum and 3-septate, fusiform ascospores lacking a gelatinous sheath. Following the key of Egea & Torrente (1994), L. salicina Zahlbr. is the most similar species in having small apothecia, 3-septate ascospores of the same size, but it differs from the new species in the black margin lacking a thick layer of white pruina (but the hymenial disc can be covered by a white pruina). Lecanactis abietina (Ach.) Körb. has longer ascospores (25–40 μm), larger apothecia and a thallus with conspicuous white-pruinose pycnidia and schizopeltic acid. Lecanactis fraudans (Räsänen) Tehler has similar ascospores (23–27(–30) × 4–5 μm), but it has an excipulum with granules/crystals that dissolve in K and recrystallize to form acicular crystals, and the apothecia margins lack a thick layer of white pruina (Egea & Torrente 1994).   
 The new species is also reminiscent of Ocellomma picconianum (Bagl.) Ertz & Tehler, but the latter species has a rudimentary excipulum and a hyaline to pale brown hypothecium (Ertz et al. 2015). All Sigridea species have a P+ orange thallus (Tehler 1993).
description: Published as part of Ertz, Damien, Flakus, Adam, Oset, Magdalena, Sipman, Harrie J. M. & Kukwa, Martin, 2015, A first assessment of lichenized Arthoniales in Bolivia with descriptions of two new species, pp. 1-25 in Phytotaxa 217 (1) on pages 16-17, DOI: 10.11646/phytotaxa.217.1.1, http://zenodo.org/record/13634573