Leptosphaeria chatkalica Lestari, Gafforov & K.D. Hyde, 2021

Lestari, Anis S., Wanasinghe, Dhanushka N., Gafforov, Yusufjon, Tennakoon, Danushka S., Thilini Chethana, K. W., Abdurazakov, Aziz, Promputtha, Itthayakorn & Hyde, Kevin D., 2021, Taxonomy and phylogenetic appraisal of Leptosphaeria chatkalica sp. nov. (Leptosphaeriaceae, Pleosporales) from Uzbekistan, Phytotaxa 520 (2), pp. 155-168 : 160

Leptosphaeria chatkalica Lestari, Gafforov & K.D. Hyde , sp. nov. ( FIGURE 2 )

Index Fungorum number:—IF 558161, Facesoffungi number:—FoF09703

Etymology:—The epithet reflects the location from where the holotype was collected

Holotype:— TASM 6155

Saprobic on woody stems. Sexual morph: Ascomata 300–400 μm high, 350–500 μm diam. (x̅ = 350 × 415 µm, n = 5), erumpent to superficial, solitary, scattered, appearing as small, raised black dots on the host surface, globose to subglobose with flattened bases, smooth, easily removed from the host substrate, black, ostiolate. Ostiole 70– 110 × 70–100 μm (x̅ = 92.4 × 80.5 µm, n = 5), central, black, papillate, inconspicuous opening by a pore, ostiole canal periphysate. Peridium 20–30 μm wide at the base, 30–80 μm at the sides, consisting two cell types of textura angularis, inner layer composed of sub-hyaline, thin-walled scleroplectenchymatous cells, outer layer comprised of dark brown thick-walled cells. Hamathecium 1.5–2.5 μm (x̅ = 2.2 μm, n = 10) wide of numerous, septate, filiform, branched, anastomosing above the asci, cellular pseudoparaphyses. Asci 150–190 × 9–12 μm (x̅ = 167.9 × 10.6 μm, n = 20), 8-spored, bitunicate, fissitunicate, cylindrical, apically rounded, long with club-like pedicel. Ascospores 20–30 × 6–9 μm (x̅ = 24.7 × 7.6 µm, n = 30), uniseriate, partially overlapping, fusiform, with narrow to acute at both ends, initially hyaline with 1-transverse septum, becoming yellowish brown, 3-septate at maturity, broader cells above central septum, verruculose, guttulate when young and lacking at the mature stage, smooth-walled, surrounded by a mucilaginous sheath. Asexual morph: Undetermined.

Material examined:— UZBEKISTAN. Tashkent Province, Chatkal Biosphere Reserve, Chatkal ridge, Western Tien Shan Mountains , 49°09’59.8 ” N, 69°44’59.6 ” E, dried stems of dicotyledon, 21 July 2019, Yusufjon Gafforov, YG - S22 - 2 ( TASM 6155 , holotype; HKAS 112714, isotype) .

GenBank numbers:—ITS: MW886101 , LSU: MW886099 , SSU: MW886100 , tef1-α: MW915583 .

Notes:—Morphology of our fungal specimen coincides with the generic concept of Leptosphaeria in having scleroplectenchyma tissue types of peridium, cellular pseudoparaphyses, cylindrical asci and transversely septate ascospores (Ariyawansa et al. 2013, De Gruyter et al. 2013). Based on the multi-gene analyses, our collection ( Leptosphaeria chatkalica ) closely nested with L. regiae with 100% ML, 100% MP and 1.00 BI statistical support ( FIGURE 1 ). Leptosphaeria chatkalica differs from L. regiae in having larger asci (150–190 × 9–12 μm), fusiform and larger ascospores (20–30 × 6–9 μm) with a mucilaginous sheath, whereas L. regiae has smaller asci (99–130 × 9–10 μm), ellipsoid to broadly fusiform and smaller ascospores (15–18 × 6–7 μm) without a sheath ( Pem et al. 2020b). Additionally, L. chatkalica ascospores are distinctly constricted at the septa. A comparison of the 460 nucleotides across the ITS (+ 5.8S) gene region of L. chatkalica and L. regiae (MFLUCC 18-1137) shows 19 base pair differences (4.12%). The main morphological differences among Leptosphaeria species are presented in TABLE 2.

Figures

FIGURE 1. ML tree based on combined LSU, ITS, SSU and tef1-α partial sequence data. Bootstrap values greater than 70% (for ML and MP) and greater than 0.95 (for BI) are indicated near the nodes. The new species given in red and type strains are in bold. The tree is rooted to Pyrenochaeta protearum (CBS 131315), P.pinicola (CBS 137997) and Didymella exigua (CBS 183.55). The scale bar represents nucleotide substitutions per site.

FIGURE 2. Leptosphaeria chatkalica (TASM 6155, holotype).a–d Appearance of ascomata on host surface. e Vertical section of an ascoma. f Close-up of an ostiole. g Section of the peridium cells. h Pseudoparaphyses. i–k Asci. l–p Ascospores. q An ascospore with a mucilaginous sheath (stained in Indian ink). Scale bars: b–d = 200 μm, e = 100 μm, f = 50 μm, g = 10 μm, h = 5 μm, i–k = 20 μm, l–q = 10 μm.