Lecanactis minuta Ertz, Flakus & Kukwa, 2015

Lecanactis minuta Ertz, Flakus & Kukwa View in CoL sp. nov. ( Fig. 5 View FIGURE 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).