Cryptocoryneum rosae Wanas. & K.D. Hyde, sp. nov.

Index Fungorum number: IF 558583; MycoBank number: MB 558583; Facesoffungi number: FoF 09944; Fig. 1

Etymology – The specific epithet “rosae” refers to the Rosa.

Holotype – KUN-HKAS 115780

Saprobic on dead wood of Rosa sp. Sexual morph Undetermined. Asexual morph Sporodochia 100–300(–450) μm diam., 20–55 μm high, pulvinate, often confluent, dark brown to black. Conidiophores arising from the stromatic cells, straight, simple, septate, hyaline to pale brown, smooth. Conidiogenous cells 5–7×4–6 μm (x̅=5.8×4.8 µm, n = 20), monoblastic, cylindrical, terminal, determinate, hyaline to pale brown. Conidia 30–50 × 20–30 μm (x̅= 36 × 27.5 µm, n = 30), l/w 1.2–1.6 (x̅= 1.3, n = 30), solitary, acrogenous, branched, cheiroid, with dark brown cap cells firmly united together, basal cells brown, cuneiform, smooth, thin-walled, with 4–12 arms (x̅=9 arms, n = 40). Arms 20–30(–37) × 3.5–6 μm (x̅= 26 × 4.5 µm, n=40), cylindrical, brown, branched at the base, smooth, (5)8–12-septate (x̅=9 µm, n=40).

Culture characteristics – Conidia germinating on PDA within 24 h and germ tubes arising from both end cells. Colonies on PDA, slow growing, reaching 2 cm diam. after 4 weeks of at room temperature, initially white becoming dark brown at maturity, slightly effuse, radially with an undulate edge, reverse blackish brown. Material examined: CHINA, Yunnan, Diqing Autonomous Prefecture, Shangri-La, Xiaozhongdianzhen, 27.425825° N, 99.845329° E, 3195 msl, on dead wood of Rosa sp. (Rosaceae), 30 August 2020, GC Ren, NX25-1 (KUN-HKAS 115780, holotype), living culture (KUMUCC 21-0033), ibid., NX25-2 (KUN-HKAS 115781), living culture (KUMUCC 21-0034).

GenBank numbers – ITS = MZ493300, MZ493301, LSU = MZ493314, MZ493315; SSU = MZ493286, MZ493287, RPB2 = MZ508418, MZ508419, TEF1-α=MZ508409, MZ508410.

Notes – Cryptocoryneum rosae was collected from Uzbekistan on Rosa and representing the first report of a Cryptocoryneum species from Central Asia and Rosa sp. (Farr and Rossman 2021). The new fungus resembling Cryptocoryneum species well in its pulvinate sporodochia, monoblastic conidiogenous cells and acrogenous, branched, cheiroid, brown conidia with multiple arms (Fig. 1). In the phylogenetic analyses of concatenated SSU, LSU, ITS, TEF1-α and RPB2, C. rosae is related to C. akitaense and C. brevicondensatum with 99% MLBS support (Fig. 2). Comparatively, C. rosae has shorter and narrower conidia (x̅=36.3×27.5 μm) than C. akitaense (x̅=49.1×38.6 μm) and C. brevicondensatum (x̅= 57.5 × 34.2 μm). In Cryptocoryneum, there were not many base pair differences between species in the ITS region (except C. condensatum). We observed, on the other hand, that there were greater differences in the TEF1-α and RPB2 gene regions. Between Cryptocoryneum rosae and C. akitaense, TEF1-α had a base pair variation of 3.2% (29/898) and RPB2 had a variation of 4% (40/988). Between Cryptocoryneum rosae and C. brevicondensatum there were 2.9% (26/898) and 3.5% (34/988) base pair differences respectively in TEF1-α and RPB2 gene regions.

Figure 1 – Cryptocoryneum rosae (KUN-HKAS 115780, holotype). a–c Appearance of sporodochia on host surface. d–g Conidia. h Germinated conidium. i, j Culture on PDA from surface and reverse. Scale bars: d=30 μm, e, f, h=20 μm, g=15 μm, i, j=3 cm

Figure 2 –  Phylogram generated from the best scoring of the RAxML tree based on combined SSU, LSU, ITS, TEF1-α and RPB2 sequence dataset to indicate the new species in Cryptocoryneaceae. Sixty strains are included in the combined analyses which comprise a total of 4357 characters. Murilentithecium clematidis (MFLUCC 14-0561 and MFLUCC 14-0562) is selected as the outgroup taxon. The best RAxML tree with a final likelihood value of − 24211.323363 is presented. RAxML analysis yielded 1272 distinct alignment patterns and 6.17% of undetermined characters or gaps. Estimated base frequencies were as follows: A=0.246394, C=0.256619, G=0.267068, T=0.229919, with substitution rates AC=1.576531, AG=4.38051, AT=1.49611, CG=1.339907, CT=10.502267, GT=1.000000; gamma distribution shape parameter alpha=0.450773. Bootstrap support values for maximum likelihood (MLBS, left) equal to or greater than 70% is given above the nodes. Ex-type strains are in bold and newly generated sequences are in blue