Introduction
According to Pérez-Ortega et al. (Reference Pawlik-Skowrońska, Purvis, Pirszel and Skowroński2010), and based on the literature cited therein, Lecanora Ach. seems to be one of the best-studied microlichen genera. However, many new species, representing various taxonomic groups of this large, diverse genus, and originating from different parts of the world, are still reported relatively frequently (e.g., Martínez & Aragón Reference Martínez and Aragón2004; Ryan et al. Reference Ryan, Lumbsch, Messuti, Printzen, Śliwa, Nash, Nash, Ryan, Diederich, Gries and Bungartz2004; Blaha & Grube Reference Blaha and Grube2007; Sipman Reference Sipman2007; van den Boom Reference van den Boom2007; van den Boom & Brand Reference van den Boom and Brand2008; Lendemer & Knudsen Reference Lendemer and Knudsen2009; Knudsen & Lendemer Reference Knudsen and Lendemer2009; Brodo Reference Brodo2010; de la Rosa et al. Reference Rosa de la, Messuti and Lumbsch2010). This indicates that the biodiversity of the lichen group is still not well recognized worldwide.
The Lecanora polytropa group, including saxicolous species containing usnic acid as a main secondary metabolite, has received the least attention within Lecanora, and to date no taxonomic treatment of the group is available. Only L. polytropa (Ehrh.) Rabenh., one of the most widely distributed species of the group apart from L. intricata (Ach.) Ach., has been investigated in advanced studies. Huneck (Reference Huneck1966) examined its chemistry, and Pawlik-Skowrońska et al. (Reference Pawlik-Skowrońska, Purvis, Pirszel and Skowroński2006) and Purvis et al. (Reference Purvis, Pawlik-Skowrońska, Cressey, Jones, Kearsley and Spratt2008) its ecophysiology. The species has also been included in molecular studies on various assemblages of species (Arup & Grube Reference Arup and Grube1998; Pérez-Ortega et al. Reference Pérez-Ortega, Spribille, Palice, Elix and Printzen2010).
A species similar in appearance to L. polytropa and L. intricata was discovered during studies on lichens of the subnival belt in the Polish Tatra Mountains. Its chemical properties, however, did not agree with either of these species. It is described here as Lecanora microloba, based on the combination of the morphological and chemical evidence.
Material and Methods
The voucher specimens were collected as part of a survey of the lichens of the subnival belt in the Polish High Tatra Mountains conducted by the second author between 2003 and 2006. Reference material was from KRAM and NY herbaria. Morphology was studied using standard techniques, with preparations mounted in water or a c. 25% solution of potassium hydroxide (K). Tissue measurements were made in water, and ascospores in K. Granulations were observed in polarized light (pol). The solubility of granules and/or crystals was tested with K and 65% nitric acid (N). Chemical analyses were carried out using thin-layer chromatography (TLC) on aluminium TLC plates in solvent systems A, B and C, following Orange et al. (Reference Orange, James and White2001).
The Species
Lecanora microloba Śliwa & Flakus sp. nov
MycoBank no.: MB518742
Species Lecanorae polytropae et L. intricatae similis; thallus crustaceus, tenuis, areolae dispersae vel rosulae minutae formans; areolae externae margine crenulato et minute lobulato. Apothecia aggregata, sessilia, non elevata nec immersa, plana, 0·3–0·6(–0·8) mm in diametro. Epithecium grosse granulatum, granulis in K solubilibus, in N insolubilibus. Ascosporae (10–) 11·2 (–13) × (5–) 5·8 (–7) µm. Acidum gyrophoricum, acidum usnicum, zeorinum et terpenum ignotum continens.
Typus: Poland, Western Carpathians, High Tatra Mts., Hińczowy Żleb gully, alt. 2200 m, 49°11′10″N, 20°03′21″E, subnival belt vegetation, on mylonitized granite rock, 22 July 2004, A. Flakus 2804 (KRAM-L—holotypus; B, hb. Flakus—isotypi).
Lecanora microloba (holotype). A–C, habitus. Scale = 0·5 mm.
(Fig. 1)
Thallus crustose, composed of well-developed, flat areoles that remain single and dispersed (Fig. 1A) or form small rosules (Fig. 1B & C), 1–3(–5) mm diam.; marginal areoles crenate to minutely lobulate, lobules c. 0·05–0·15 mm long and 0·05–0·1 mm wide, somewhat raised from the substratum; surface smooth, corticated, grey-green to yellow-green. Photobiont a chlorococcoid green alga, cells up to 15 µm diam.
Apothecia occurring singly on the areoles, or more often clustered and grouped predominantly in the centre of rosules, broadly sessile to slightly constricted at base, flat, only slightly convex when older, 0·3–0·6(–0·8) mm diam.; disc plane, smooth, yellowish grey to yellowish green, epruinose; margin faintly prominent, or level with the disc, smooth, entire, even, uniform, epruinose, concolorous with the thallus, rarely concolorous with the disc. Thalline exciple becoming excluded with only clusters of algae present on both sides of the apothecial section; cortex indistinctly delimited, ± uniform in thickness, up to 30 µm, more or less obscured by granules (pol+; insoluble in K, soluble in N); parathecium distinct, well delimited, prosoplectenchymatous, 35–60 µm wide, obscured entirely or in the uppermost part by granules (pol+; soluble in K, insoluble in N); epithecium shades of yellow or pale brown, granular (pol+), granules abundant, superficial and between paraphyses tips, fine to coarse (soluble in K and insoluble in N); hymenium hyaline, 50–70 µm high; subhymenium indistinct; hypothecium hyaline or almost so, 60–90 µm high, composed of adglutinated hyphae. Paraphyses thick, septate, simple to sparsely branched, apices slightly expanded, up to 2 (–2·5) µm wide, not pigmented, free in K. Asci Lecanora-type, clavate, 8-spored; ascospores colourless, non- septate, ellipsoid, (10–) 11·2 ± 1·01 (–13) × (5–) 5·8 ± 0·69 (–7) µm [n = 25].
Pycnidia not seen.
Chemistry. Gyrophoric acid (major), usnic acid (major), zeorin (major), and an unidentifed terpenoid (Rf classes A 3, B 2–3, C 2–3; minor). Thallus (cortex) K± yellowish, C+ rose, KC+ rose, P−, UV−; apothecial disc and margin K± yellowish, C+ rose, KC+ rose, P−, UV−.
Etymology. The epithet denotes the minutely lobulate marginal areoles formed by the new species.
Taxonomic notes. The presence of gyrophoric acid in the cortex of the thallus, at the apothecial margin, and the disc is an important diagnostic character of this new species. Lecanora microloba is also distinguished by the minutely lobulate marginal areoles of the thallus, and the apothecia that are clustered several together and grouped predominantly in the centre of the rosules. The apothecia of the species are up to 0·6(–0·8) mm diam., sessile, flat and constantly pale in colour. Anatomically the species is characterized by coarse granules in the epithecium that are distinctly bright in polarized light.
Lecanora polytropa and L. intricata are the most closely related species and are most likely to be confused with L. microloba. However, they clearly differ from it both in morphology and in chemistry. Lecanora polytropa is characterized by its thallus that is composed of dispersed granules or areoles with even margins and apothecia that are quite large, up to 1(–1·5) mm diam., sessile but often becoming strongly constricted at the base, raised, and convex. The chemistry of L. polytropa is also significant. The species produces usnic and rangiformic acids, zeorin, and ± eulecanoral. Lecanora intricata is clearly distinguished by its contiguous crustose thallus with crenate margins and numerous, sessile to immersed apothecia, 0·4–1(–1·5) mm diam. that are often darkened. Additionally, L. intricata contains exclusively usnic acid and zeorin.
Anatomically, L. microloba shares with L. polytropa and L. intricata apothecial margins with a well-developed parathecium, a granular epithecium with granules that are soluble in K, thick, simple to sparsely branched paraphyses with slightly expanded apices and ellipsoid ascospores. However, the new species is relatively easily distinguished by the epithecial granules, those of L. polytropa and L. intricata being fine, negative or ± bright in polarized light, whereas those of L. microloba are coarser and distinctly bright in polarized light. Although this character is very helpful in delimiting the latter species, it is worth noting that its taxonomic value must be evaluated based on a global, urgently needed revision of the L. polytropa group.
Because of its chemistry, L. microloba is also reminiscent of L. gyrophorica Lendemer. The last species produces usnic and gyrophoric acids, zeorin, 3 unidentified terpenoides and leucotylin (Knudsen & Lendemer Reference Knudsen and Lendemer2009). However, L. gyrophorica is a typical member of the L. muralis group with a placodioid thallus, forming large rosettes, up to 1–2 cm diam. and therefore the separation of the two taxa is obvious. Additionally, gyrophoric acid is located in the medulla of the latter species.
Discussion. Secondary metabolites produced by different groups of taxa within Lecanora have been examined in detail. Studies by Elix et al. (Reference Elix and Lumbsch1989), Elix & Crook (Reference Elix and Crook1992), Brodo & Elix (Reference Brodo and Elix1993), Lumbsch et al. (Reference Lumbsch, Feige and Elix1994, Reference Lumbsch, Feige and Elix1995), Poelt et al. (Reference Poelt, Leuckert and Roux1995), and Elix & Lumbsch (Reference Elix and Lumbsch1996) are especially noteworthy and provided new, interesting data. For example, Elix & Crook (Reference Elix and Crook1992) discovered a joint occurrence of chloroxanthones in several Lecanora species, Poelt et al. (Reference Poelt, Leuckert and Roux1995) presented data on the chemical content of a few members of the L. dispersa group that were considered to lack lichen products, Brodo & Elix (Reference Brodo and Elix1993) argued against a formal taxonomic recognition of species groups based on chemical data, Lumbsch et al. (Reference Lumbsch, Feige and Elix1994) discussed chemical variation in selected representatives of the L. subfusca group, and finally Lumbsch et al. (Reference Lumbsch, Feige and Elix1995) contributed to the recognition of numerous new species of the group that contain usnic acid in addition to atranorin. Based on those studies the taxonomic importance of chemical variation in the genus may be considered controversial. However, the chemical content of taxa is often successfully used to support a new species circumscription (e.g. Printzen Reference Printzen2001).
Gyrophoric acid is a rare lichen product in Lecanora and was known to occur only in a few species. Lecanora salina H. Magn. (Elix & Crook Reference Elix and Crook1992; Śliwa Reference Śliwa2007) and L. congesta Clauzade & Vězda (Clauzade & Vězda Reference Clauzade and Vězda1969; Edwards et al. Reference Edwards, Aptroot, Hawksworth, James, Smith, Aptroot, Coppins, Fletcher, Gilbert, James and Wolseley2009) are the members of the L. dispersa group containing the substance. Gyrophoric acid as a minor metabolite was also recorded in L. epibryon subsp. broccha (Nyl.) Lumbsch, a taxon that belongs to the L. subfusca group (Lumbsch et al. Reference Lumbsch, Feige and Elix1994). The most recent report of two new species producing the substance: L. gyrophorica representing the L. muralis group, and L. munzii K. Knudsen & Lendemer representing the L. saligna group (Knudsen & Lendemer Reference Knudsen and Lendemer2009), as well as the discovery of the new species of L. polytropa group described here indicate that gyrophoric acid is a more common lichen product in the genus than previously thought. More detailed studies of even common species may uncover additional Lecanora species producing it.
Distribution and ecology. The new species is known only from two localities in the Polish Tatra Mountains, where it was recorded on mylonitized granite rock intrusions in the highest climatic vegetation belt of the Carpathians. The small tectonic zones of the crystalline part of the Tatra Mountains are considered very important for the biodiversity of the Carpathians (see e.g. Flakus Reference Flakus2007). Based on a revision of extensive herbarium material of L. polytropa and L. intricata available at the KRAM herbarium, we conclude that the new species may be specific to the very special habitat described above, and it may subsequently be found in other places with this type of rock.
The accompanying species with L. microloba were: Aspicilia simoënsis Räsänen, Bellemerea alpina (Sommerf.) Clauzade & Cl. Roux, B. subsorediza (Lynge) R. Sant., Lecanora polytropa, Lecidea auriculata Th. Fr., Porpidia macrocarpa (DC.) Hertel & A. J. Schwab, Rhizocarpon geographicum (L.) DC., and Thelidium papulare (Fr.) Arnold. Lecanora microloba is a host species of the lichenicolous fungus Muellerella erratica (A. Massal.) Hafellner & V. John.
Additional specimens examined. Poland: Western Carpathians: High Tatra Mts., Przełączka pod Zadnim Mnichem pass, alt. 2135 m, 49°11′19″N, 20°03′06″E, subnival belt, mylonite area, 2004, A. Flakus 3178/1 (KRAM—paratype).
Selected reference material seen. Lecanora gyrophorica: USA: Missouri: Lawrence Co., Paris Springs Access, c. 3·5 miles W of Halltown, c. 0·5 miles N of junction of Highways 96 & 266, vicinity of Turnback Cave, 37°11′39″N, 93°41′34″W, mesic E-facing limestone bluff, on chert in overgrown glade, 2006, J. C. Lendemer 6460 (NY—holotype).
L. intricata: Poland: Western Carpathians: High Tatra Mts., Hińczowa Przełęcz pass, alt. 2323 m, 49°11′16″N, 20°03′19″E, subnival belt, mylonite area, on granite rock, 2003, A. Flakus 1154,1 (KRAM); Przełączka pod Zadnim Mnichem pass, alt. 2135 m, 49°11′19″N, 20°03′06″E, subnival belt, mylonite area, on mylonitized granite rock, 2003, A. Flakus 1898 (KRAM); Rysy Mt., alt. 2499 m, 49°10′46″N, 20°05′17″E, subnival belt, on vertical granite rock, 2003, A. Flakus 1364 (KRAM); West Tatra Mts., Dolina Chochołowska valley, Polana Chochołowska glade, alt. 1105 m, 49°14′16″N, 19°47′47″E, intensive pasture, on rock, 2004, L. Śliwa 3117 (KRAM); Dolina Kościeliska valley, Stare Kościeliska glade, alt. 965 m, 49°15′31″N, 19°52′08″E, intensive pasture, on rock, 2004, L. Śliwa 2728 (KRAM).
L. polytropa: Poland: Western Carpathians: High Tatra Mts., Hińczowy Żleb gully, alt. 2200 m, 49°11′10″N, 20°03′21″E , the subnival belt, mylonite area, on mylonitized granite rock, 2004, A. Flakus 2827 (KRAM); Miedziane Mt., alt. 2220 m, 49°12′07″N, 20°03′03″E, the subnival belt, on granite stone, 2003, A. Flakus 601 (KRAM); Szpiglasowy Wierch Mt., W ridge, alt. 2170 m, 49°11′51″N, 20°02′23″E, the subnival belt, on vertical granite rock, 2003, A. Flakus 687 (KRAM); West Tatra Mts., Dolina Kościeliska valley, Stare Kościeliska glade, alt. 965 m, 49°15′31″N, 19°52′08″E, intensive pasture, on rock, 2004, L. Śliwa 2733 (KRAM); Tatra Mts. area, Magura Witowska range, Molkówka glade, alt. 970 m, 49°15′21″N, 19°49′15″E, extensive pasture, on stone, 2004, L. Śliwa 2745 (KRAM).
We thank the curator of NY and James C. Lendemer (New York) for kindly sending us the reference material on loan, Martin Kukwa (Gdańsk) for valuable discussion on chemistry, Wojciech Paul (Kraków) for his help with the Latin diagnosis, and Sergio Pérez-Ortega (Madrid) for providing a recently published article. Our most sincere thanks are due to Harrie J. M. Sipman (Berlin) for constructive comments and corrections on the manuscript. This study was supported by the Polish national fund for scientific research in the years 2007–2009 (grant no. N304 050 32/2318 of MNiSW).
