Lecanoropsis omissa Palice, Ivanovich & Printzen, 2025

Ivanovich, Cristóbal, Weber, Lilith, Palice, Zdeněk, Hollinger, Jason, Otte, Volker, Sohrabi, Mohammad, Sheehy, Steve & Printzen, Christian, 2025, A taxonomic revision of the lichen genus Lecanoropsis (Lecanoraceae), Phytotaxa 695 (1), pp. 1-56 : 22-24

Lecanoropsis omissa Palice, Ivanovich & Printzen , sp. nov. Fig. 8 .

MycoBank nº: 847151

Type:— RUSSIA. Republic of Adygea: Maykopsky District, 1830 m alt., 44°4.6665’ N 40°0.8419’ E, 17 June 2016, Z. Palice 21226 ( PRA — holotype!, FR-0183020!, FR-0362735!— isotypes). Lecanomics Codes: 245, 253.

Diagnosis: Thallus usually endosubstratal; apothecia flat to convex, apothecial disc typically pruinose, pale pink to red-brown, apothecial margin thin, smooth and at the same level with disc, usually darker than the disc, becoming excluded in old apothecia; microconidia narrowly cylindrical; producing usnic acid.

Thallus usually endosubstratal, or seemingly episubstratal composed mainly of non-symbiotic algae (on wood), forming a dull, thin crust without a distinct cortex, yellowish. Photobiont a chlorococcoid/trebouxioid alga. Apothecia rounded, dispersed or forming small groups, when mature appressed to sessile, 0.2–0.4 (–0.5) mm diameter. Apothecial disc flat to convex, pale pinkish to orange-brown or reddish brown, matte to weakly glossy, with a fine white pruina most pronounced and striking in fresh material, or seemingly epruinose when older. Apothecial margin in young apothecia thin, smooth, weakly pruinose or epruinose, level with the discs or slightly prominent, becoming excluded in older apothecia. (0.02–)0.03–0.04(–0.05) mm wide. Reddish brown to brown, usually darker than the disc. Amphithecium well developed, algal layer usually discontinuous, confined to the mid-basal area of the apothecial edge in cross-section. Amphithecial cortex distinctly delimited from inner algal layer, more or less uniformly wide, (21–)24–31(–39) µm wide laterally, (15–)18–21(–25) µm wide basally, formed by anticlinally arranged, radiating and anastomosing hyphae, apically unthickened or slightly widened up to 2 µm. Parathecium indistinct. Epihymenium typically hyaline, rarely with streaks of brown and green pigment in the epihymenium and the amphithecial cortex, containing a mixture of Cinereorufa -green and possibly Arnoldiana-brown. With a thin layer of finely granulose, ochraceous epipsamma, sometimes locally streaking into hymenium or amphithecial cortex as irregular aggregates. Hymenium hyaline or with aggregates of epipsammoid granules, in older apothecia sometimes with golden oily guttules, (28–)31–39(– 43) µm high. Subhymenial layers hyaline, (46.5–)55–126(–155) µm. Paraphyses simple to sparsely branched and/or anastomosing, ca. 1–1.5 µm wide in the middle of the epihymenium, apices not or weakly capitate, 1.5–2.5 µm, sometimes up to ca. 4 µm wide, gel sheaths at apices ca. 3–4.5 µm, pigmented brown or not. Spores narrowly ellipsoid, simple, hyaline, (6.5–)8.0–10.0(–11.9) × (1.7–)3.1–3.9(–4.3) µm. Pycnidia inconspicuous, immersed in the substrate, with a brownish wall. Conidia : Microconidia narrowly cylindrical, straight or slightly bent, 5–8 × 0.8–1 µm. Other types of conidia were not found.

Chemistry: Usnic acid.

Substrate: Lignicolous or corticolous.

Ecology: In well-lit natural forests; samples collected in two localities: a temperate deciduous forest in the Western Carpathians ( Slovakia) with dominating Quercus cerris , visited several years after a fire accident at elevation ca. 600 m; and a montane forest dominated by the Caucasian fir ( Abies nordmanniana ) in the Northern Caucasus ( Russia) at elevation ca. 1830 m. The bedrock is limestone in both localities.

Notes: The new species is very similar to Lecanoropsis latens , however, several key characters separate L. omissa ( Lecanora sp. A sensu Ivanovich et al., 2021) from L. latens . Lecanoropsis latens appears to develop a corticated amphithecium typical in Lecanoropsis . On the other hand, Lecanoropsis omissa shows a cortex that appears to radiate downwards to the base, resembling an excipulum (excipulum proprium sensu Henssen & Jahns, 1974). Spore sizes are also slightly different, being rounder, shorter and aseptate in L. omissa . L. latens spores are, however, slightly longer, slender and rarely 1-septate [(6.0–)9.5–9.9(–11.0) × (2.5–)2.8–3.3(–4.0) µm ( Printzen 2001)]. Lecanoropsis latens also has been reported to have usnic acid and zeorin, while L. omissa produces only usnic acid. Finally, distribution and ecological preferences are different between these species: L. latens has been collected in lowland areas in California; L. omissa is so far known only from two areas occurring in native forests in central-east Europe (Muránská planina in W Carpathians) and the Caucasus. Interestingly, the Carpathian samples were collected on the thick bark of oaks that had been charred a few years before. Own apothecia, however, grew in spots without visible charring.

Etymology: From the Latin omissus, meaning neglected. This species can easily be mistaken for poorly developed forms of other taxa of Lecanoropsis .

Additional specimens studied: SLOVAKIA. Banskobystrický kraj: Okres Revúca , 597 m alt., 48°45.9569’ N 20° 4.7335’ E, 07 Oct. 2019, D. Blanár, A. Guttová, J. Halda & Z. Palice 27765 (FR-0362736; PRA), Lecanomics code: 566 ; 48°45.9499’ N 20°4.7417’ E, 07 October 2019, D. Blanár, A. Guttová, J. Halda & Z. Palice 27766 (FR-0362737; PRA), Lecanomics code: 567 ; Western Carpathians, Muránska planina National Park , Muráň , Nature Reserve Šiance , 597 m alt., 48°45.9566’ N 20°4.7150’ E, 07 October 2019, D. Blanár, A. Guttová, J. Halda & Z. Palice 27840 (FR-0362738; PRA), Lecanomics code: 577 ; 48°45.9566’ N 20°4.7150’ E, 07 October 2019, D. Blanár, A. Guttová, J. Halda & Z. Palice 27840 (FR-0362739; PRA), Lecanomics code: 584 .

Figures

FIGURE 8. Lecanoropsis omissa. A, habitus. B, apothecial section in LCB. C, microconidia in Phloxine B. Specimens: A = Russia, Adygea, Z. Palice 21226 (FR-0183020; L245); B = Slovakia, Banskobystrický kraj, Z. Palice 27840 (FR-0362739; L584); C = Slovakia, Banskobystrický kraj, Z. Palice 27765 (FR-0362736; L566). Scales: A = 500 µm; B = 20 µm; C = 10 µm.