Pleopunctum thailandicum J.Y. Zhang, Y.Z. Lu & K.D. Hyde, sp. nov.
Index Fungorum number: IF 558394; MycoBank number: MB 558394; Facesoffungi number: FoF 09804; Fig. 1
Etymology – The specific epithet “thailandicum” reflects the country, where the specimen was collected, Thailand.
Holotype – MFLU 21-0043
Saprobic on dead branches of unidentified plant. Sexual morph Undetermined. Asexual morph Hyphomycetous. Colonies on natural substrate dry forming sporodochial conidiomata, superficial, scattered, gregarious, punctiform, glistening, oval. blackish brown. Mycelium immersed in the substrate, composed of septate, branched, hyaline to paleyellow. Conidiophores 2.5–5 μm wide micronematous or macronematous, mononematous, cylindrical or truncate, erect, unbranched, hyaline to brown, sometimes reduced to conidiogenous cells. Conidiogenous cells, monoblastic, holoblastic, terminal, integrated, subspherical or ampulliform, hyaline. Conidia 29–38×19–25 μm (x̅ =34×22 μm, n=25), acrogenous, solitary, muriform, oval to ellipsoidal, multiseptate, slightly constricted at the septa, oval to ellipsoidal, thick-walled, smooth, brown to hyaline at upper and lower cells when immature, dark brown when mature, rounded at apex, truncate at base, sometimes with a hyaline, globose basal cell, 8–20×8.5–18.5 μm (x̅=13×12 μm).
Culture characteristics – Conidia germinated on WA within 15 h at room temperature. Colonies reaching 15 mm at 2 weeks, convex, rough surface with edge entire, radiating outwards; reverse smooth, white to pale yellowish at the centre.
Material examined – THAILAND, Chiang Mai Province, Mae Taeng, Ki Lek, Chang Wat (19°07′52.3″ N 98°45′35.7″ E), on dead branches of unidentified plant, 8 August 2019, N. Wu, N17 (MFLU 21-0043, holotype); ex-type living culture, MFLUCC 21-0039.
GenBank numbers – ITS=MZ198894, LSU=MZ198896, TEF1-α: MZ172461.
Notes – The phylogenetic analysis reveals that a new species, Pleopunctum thailandicum belongs to Pleopunctum, where it is sister to P. clematidis with 100% MLBS, 1.00 BYPP support (Fig. 2). Pleopunctum thailandicum is similar to P. clematidis in having superficial and brown colonies, holoblastic, monoblastic conidiogenous cells and muriform, oval to ellipsoidal conidia (Liu et al. 2018; Phukhamsakda et al. 2020). However, P. thailandicum differs from P. clematidis by its black and larger conidia, and lacks dimorphic conidia (Fig. 1).
Figure 1 – Pleopunctum thailandcum (MFLU 21-0043, holotype). a–c Colonies on natural substrates. d, e Conidiophores with conidiogenous cells. f–h Conidiogenous cells and conidia. i Conidium with basal hyaline cells. j Germinated conidium. k, l Culture on PDA from surface and reverse. Scale bars: b=250 μm, c=100 μm, e–g, i, j=20 μm, d, h=10 μm
Figure 2 – Phylogram generated from Bayesian analysis based on combined LSU, SSU, ITS and TEF1-α sequence data. Twenty-one strains are included in the combined analyses which comprised 3338 characters (866 characters for LSU, 999 characters for SSU, 550 characters for ITS, 923 characters for TEF1-α) after alignment. Tree topology of the maximum likelihood analysis is similar to the Bayesian analysis. The best RAxML tree with a final likelihood value of − 11657.841536 is presented. Estimated base frequencies were as follows: A=0.239152, C=0.258772, G=0.277763, T=0.224314; substitution rates AC=1.083541, AG=2.347613, AT=1.453520, CG=1.144548, CT=7.950168, GT=1.000000. Bootstrap support values for ML greater than 70% and Bayesian posterior probabilities greater than 0.95 are given near nodes respectively. The tree is rooted with Lophiohelichrysum helichrysi (MFLUCC 15-0701) and Lophiostoma macrostomum (JCM 13,544). Ex-type strains are in bold and newly generated sequence is in blue