Lecanora flavocrassa de la Rosa & Messuti, 2016

Rosa, Iris Nadia De La, Passo, Alfredo, Rodríguez, Juan Manuel, Chiapella, Jorge Oscar & Messuti, María Inés, 2016, A new species and new records of Lecanora (Lecanoraceae, lichenized Ascomycota) with usnic acid from the Antarctic region, Phytotaxa 261 (2), pp. 185-193 : 186-188

Lecanora flavocrassa de la Rosa & Messuti sp. nov.

MycoBank No.: MB816991

Thallus crustose, lignicolous, yellowish, thick areolate, verrucose; with usnic acid, zeorin and thiophanic acid as secondary metabolites. Apothecia yellowish, lecanorine, relatively large, 0.8–3.0 mm diam. Margin persistent, well-developed, flexuous. Asci clavate 8- spored. Ascospores hyaline, simple, narrowly ellipsoid, 10–14(–16) × 4–6 μm.

Type: — ANTARCTIC PENINSULA. Danco Coast: Primavera Station, Punta Cierva (Cierva Cove), on a small wooden building at the base near sea shore, north-west facing, on painted wood, elev. 13 m, 64°09′15.9″S, 60°57′17.4″W, 11 February 2014, A. Passo & J.M. Rodríguez (holotype BCRU 5388).

Figs. 1 , 2

Thallus crustose, yellowish to pale yellowish-greenish, areolate, warted-verrucose, continuous to ±disperse, surface smooth to wrinkled, ±shiny, sometimes pruinose, areoles irregular, strongly convex, rough, scabrid. Prothallus not visible.

Apothecia lecanorine, disciform to more frequently irregular, immersed to adnate when young, widely sessile, strongly constricted at base to subpedicelate in mature apothecia, numerous, usually clustered in groups but not fused, 0.8–3.0 mm diam. Disc concave or flat-concave, sometimes slightly pruinose, yellowish, creamy-yellowish, pale yellowish orange. Margin persistent, prominent, rough, rarely smooth, entire to more frequently strongly flexuous, epruinose, concolorous with thallus, parathecial ring well-developed, paler than disc. Amphithecium well-developed, without calcium oxalate crystals, with small granules (pol+), K-soluble; algal layer ±continuous, irregular; amphithecial cortex poorly developed, pale brownish, thin, uniform in thickness, 10–20 μm wide, with small crystals (pol+), soluble in K. Parathecium hyaline, without crystals (pol−), most developed at the upper part. Epihymenium brown, granular (pol+), ca. 16.5 μm high, granules and pigment soluble in K. Hymenium hyaline, with oil droplets, 50–65 μm high. Hypothecium well-developed, hyaline, prosoplectenchymatic, with oil droplets, hyphae thick walled, gelatinous, 50– 260 μm wide. Paraphyses thick, up to 1.6 μm wide, branched and anastomosed, with dilated tips 3.2 μm wide. Asci Lecanora - type, 8-spored, clavate, 38–47 × 10–14 μm. Ascospores hyaline, simple, narrowly ellipsoid to bacilliform, 10–14(–16) × 4–6 μm. Pycnidia not seen.

Chemistry:— Thallus and apothecial margin K+ yellow-orange, C−, KC+ yellow, P−; UV−. Secondary metabolites detected by HPTLC: Usnic acid, zeorin, thiophanic acid and two unknown substances ([1) spot grey to pale greyish,

UV+ orange after heating, R f A 83 (class 8), R f C 78 (class 8–9); 2) spot colorless, water-repellent, R f classes 3, R f A 36, R f C 35.]).

Ecology and distribution:— The new species, L. flavocrassa , was found on anthropogenic substrate (worked wood), and it is known only from the type locality in the Primavera Station, Antarctic Peninsula. The possibility that this species has been introduced by man cannot be excluded. This lichen could have been established on imported timber, but additional material is required to clarify the substrate preference.

Etymology:— The specific epithet flavocrassa refers to the yellowish color of the thallus and the thick, strongly convex areoles.

Discussion:— Lecanora flavocrassa is characterized by a thick yellowish thallus, with relatively large apothecia and narrowly ellipsoid to bacilliform ascospores. The peculiar combination of morphological, anatomical and chemical characters, not observed in other species of the same genus, allows to put it apart as a new species. Lecanora frustulosa (Dicks.) Ach. is a saxicolous species, previously registered for South Shetland Islands (Livingston Island, South Bay) that is most likely to be confused with L. flavocrassa ( Table 1). They are distinguished by the color of apothecial discs, being darker in L. frustulosa and by the absence of fatty acids, stictic, norstictic and cryptostictic acids in L. flavocrassa . Moreover, according to Vänskä (1984), the areoles in L. frustulosa have medullary hyphae which form a relatively broad but low central umbilicus-like structure, a character not observed in the new species. Lecanora albellula Nyl. a corticolous species distributed in Europe and North America, has also a corticated amphithecium, with a distinct cortex ±uniform in thickness, ascospores 3.5–6.2 μm in width and hymenium 40–60 μm high ( Table 1). However, this species has an inconspicuous thallus, smaller apothecia, beige to orange-brown discs, thalline margin often reduced or absent and isousnic acid as major compound ( Printzen 2001; Ryan et al. 2004; Edwards et al. 2009). Lecanora varia (Hoffm.) Ach. , another corticolous and lignicolous species present in Europe and North America, also resembles L. flavocrassa by its yellowish to greenish thallus, apothecia up to 2.0 mm diam., with persisting lecanorine margin and amphithecium with granules dissolving in KOH ( Śliwa & Wetmore 2000; Printzen 2001; Ryan et al. 2004; Edwards et al. 2009). The thallus is clearly more developed in the new species, showing a thin amphithecial cortex of uniform thickness, longer ascospores and zeorin in addition to usnic acid ( Table 1).

Lecanora flavocrassa can be regarded as a member of the L. varia group by its lignicolous, well-developed yellowish thallus, lecanorine apothecia, corticated amphithecium lacking oxalate crystals and usnic acid as main substance. Several members of the L. varia group also have large apothecia, with corticated amphithecia and containing usnic acid, zeorin and thiophanic acid, but in those species the thallus is poorly developed and they show an inconspicuous parathecium and a more developed amphithecial cortex. In L. flavocrassa the thallus is clearly thicker and at the same time discs are pale yellowish. Additional collections are needed in order to register the phenotypic variation of this new species.

Figures

FIGURE 1. A. The Antarctic region, black arrow point to the area of the Primavera Station where the specimen of L. flavocrassa was found. B. A view of the Primavera Station.

FIGURE 2. Lecanora flavocrassa de la Rosa & Messuti sp. nov. (holotype BCRU 5388). A. habitus. B. detail of ascus apex Lecanoratype. C. ascospores. Scales: A = 1 mm; B, C = 10 μm.