Lichenopeltella sakhalinensis Zhurb., 2025

Zhurbenko, Mikhail P. & Ezhkin, Alexandr K., 2025, Lichenicolous fungi of the Sakhalin Region of the Russian Federation, including Lichenopeltella sakhalinensis sp. nov. (Trichothyriaceae, Dothideomycetes, Ascomycota), Phytotaxa 712 (2), pp. 177-185 : 178-180

Lichenopeltella sakhalinensis Zhurb. , sp. nov. ( FIGURE 1 )

MycoBank number: 860076

Diagnosis:—Differs from Lichenopeltella heterodermiicola mainly in the smaller ascospores, 9.5–13 × 3–4 µm vs 13–14.5 × 3.5–5 µm, and a different host selection, Parmelia ( Parmeliaceae ) vs Heterodermia ( Physciaceae ).

Type:— RUSSIAN FEDERATION. Sakhalin Region: Sakhalin Island, Mt. Mitsul near Yuzhno-Sakhalinsk, 47°03′02.3″N, 142°30′39.5″E, elev. 536 m, coniferous forest with Betula ermanii , on ±decaying thallus of Parmelia squarrosa and occasionally on bordering parts of a crustose Pertusaria -like lichen growing on bark of Betula ermanii , 20 May 2017, A.K. Ezhkin s.n. (holotype LE F-355072!).

Description:— Vegetative hyphae not observed. Ascomata catathecia, brownish black, glossy, broadly conical/ scutate, often adpressed but with a raised central ostiolar part, orbicular to irregularly pentangular, quadrangular, rectangular or occasionally triangular in surface view, with a non-fimbriate, ±wavy margin, (64–)88–116(–132) µm in diam. (n = 70), 28–50 µm high, superficial, dispersed to loosely aggregated, occasionally contiguous; ostiole up to 20 µm in diam., sometimes rather indistinct, without setae. Upper wall light brown to brown, K+ brownish grey, one cell thick, mainly composed of radially-arranged, rectangular or occasionally quadrangular cells 4–7.5 × 2.5–5 µm. Ostiolar collar composed of 2–3 rings of slightly darker than the rest of the upper wall, thick-walled, ±quadrangular cells 3–4 µm across around the ostiole. Lower wall similar in structure to the upper wall but paler. Periphyses not observed. Putative paraphyses rather indistinct, 1.5–3 µm wide. Asci bitunicate in structure, obclavate (widened in the lower half), wall markedly thickened at the top, with a distinct internal apical beak, sessile, (32.5–)33.5–40(–46) × (7.5–)9–11.5(–12) µm (n = 14, in K), (4–)8-spored, I−, K/I− except for the ascoplasm turning brownish orange. Ascospores hyaline, cylindrical-clavate/skittle-shaped, with rounded ends, (9.5–)10.5–12(–13) × 3–3.5(–4) µm, l/w = (2.8–)3.1–3.5(–3.9) (n = 93, in water or K), with a median septum, rarely slightly constricted at the septum, setulae not observed, usually with 1–3 large lipid guttules in each cell, smooth-walled, non-halonate, irregularly biseriate in the ascus.

Etymology:—Named after Sakhalin Island, where the type was collected.

Distribution and host:—The new species is known from the type collection in Sakhalin Island, Pacific Russia, growing on ±decaying (partially discoloured or darkened) thallus of Parmelia squarrosa ( Parmeliaceae , Lecanorales ) and occasionally on bordering parts of a crustose Pertusaria -like lichen settled on bark of Betula ermanii .

Notes:—To date, 51 species of Lichenopeltella , Trichothyriaceae , Dothideomycetes, Ascomycota are known (Species Fungorum 2025); of these L. mizerniana G. Worobiec (2020: 800) is a fossil-species from Pliocene deposits ( Worobiec & Worobiec 2020), 40 species are obligately lichenicolous ( Diederich et al. 2018, Roux 2020, Zhurbenko 2021), and ten species grow on decaying woody and herbaceous plants ( Ellis 1977, Jones et al. 1999).

Lichenicolous species of Lichenopeltella are mostly confined to a particular lichen genus, or very rarely, lichen family. The diagnostic features of six previously known species of Lichenopeltella growing on genera of the lichen family Parmeliaceae , to which Parmelia belongs, are given in Zhurbenko (2021: Table 1). All these species differ from Lichenopeltella sakhalinensis by longer ascospores (≥ 12 µm long), the presence of ascospore setulae, and different host genera. In terms of such features as ascoma size, the absence of ostiolar setae and ascospore setulae, and (4–)8- spored asci, the new species is most similar to Lichenopeltella heterodermiicola M.S. Cole & Hawksworth (2002: 392) ( Cole & Hawksworth 2002). However, the latter is characterized by somewhat longer asci, 41–46 µm long, and larger ascospores, 13–14.5 × 3.5–5 µm, in addition to a different host genus ( Heterodermia ).

The establishment of the examined fungus on old lichen thallus suggests that it can be more or less saprobic. Of the ten species of Lichenopeltella growing on decaying vascular plants, L. norfolciana (J.P. Ellis) P.M. Kirk & Minter, IMI Descriptions of Fungi and Bacteria (2007) readily differs from L. sakhalinensis in the ascospores with up to six septa; L. alpestris (Sacc.) P.M. Kirk & Minter, IMI Descriptions of Fungi and Bacteria (2007), L. ammophilae (J.P. Ellis) P.M. Kirk & Minter, IMI Descriptions of Fungi and Bacteria (2007), L. cupularum (J.P. Ellis) P.M. Kirk & Minter, IMI Descriptions of Fungi and Bacteria (2007), L. palustris (J.P. Ellis) P.M. Kirk & Minter, IMI Descriptions of Fungi and Bacteria (2007), and L. quinquecladiopsis (E.B.G. Jones, Sivichai & Hywel-Jones) E.B.G. Jones & D. Hawksw. (2001: 642) have ascospores with appendages ( Ellis 1977, Jones et al. 1999). Lichenopeltella pinophylla (Höhn.) P.M. Kirk & Minter, IMI Descriptions of Fungi and Bacteria (2007) is distinct in smaller catathecia (80–90 µm in diam.) and smaller ascospores, 8–11 × 1.5–3 µm ( Ellis 1977). Lichenopeltella fimbriata (J.P. Ellis) P.M. Kirk & Minter, IMI Descriptions of Fungi and Bacteria (2007) has smaller catathecia (60–80 µm in diam.) with a fimbriate margin, smaller asci (18–27 × 6–7 µm), and smaller ascospores (6.5–8 × 1.5–3 µm) with a dark septum ( Ellis 1977). Lichenopeltella nigroannulata (J. Webster) P.M. Kirk & Minter, IMI Descriptions of Fungi and Bacteria (2007) has smaller catathecia (54–90 µm in diam.), smaller asci (20–26 × 6–8 µm), and smaller ascospores (6.5–10.5 × 1.5–3 µm) with pointed ends ( Webster 1952, Ellis 1977). Lichenopeltella salicis (J.P. Ellis) P.M. Kirk & Minter, IMI Descriptions of Fungi and Bacteria (2007) differs in the abundant superficial mycelium, composed of pale yellow hyphae, and smaller ascospores, 6.5–9 × 1.5–2 µm ( Ellis 1977).

Despite the lack of molecular data the newly described species is readily distinguished from the other described Lichenopeltella species by its peculiar morphology and ecology.

Figures

FIGURE 1. Lichenopeltella sakhalinensis (holotype).A, ascomata on the thallus of Parmelia squarrosa. B, upper wall of ascoma in water. C, putative paraphyses in K. D, asci in K (top) and K/I (bottom). E, ascospores in K. Scales:A = 50 μm, B = 20 μm, C–E = 10 μm.