Xenoplectosphaerella clematidis Jayaward., Phukhams., & K.D. Hyde, sp. nov.

MycoBank number: MB 557304; Index Fungorum number: IF 557304; Facesoffungi number: FoF 07326, Fig. 115.

Etymology: Name refers to the host plant, Clematis.

 Holotype: MFLU 17–1475

Saprobic on dead stems of Clematis subumbellata. Sexual morph: Ascomata 90–100 × 90–110 μm (= 98 × 105 μm, n = 5), single or gregarious, immersed under the host epi- dermal layer, visible as black spots on host substrate, obpyriform, coriaceous with minute papilla. Ostioles papillate, filled with periphyses. Peridium 7–12 μm wide, composed of 7–10 layers of thin-walled cells of textura angularis mixed with textura globosa, inner layers, hyaline, thick- walled. Paraphyses numerous, 1.5–3.5 μm ( = 2.5 μm, n = 30), septate, narrowed and tapering towards the apex. Asci 31–50 × 10–15 μm (= 38 × 12 μm, n = 20), unitunicate, broad clavate to broad fusiform, simple pedicel, apex flat, with J-, conspicuous apical or subapical ring. Ascospores 10–17 × 4–5 μm (= 13 × 4 μm, n = 50), biseriate, overlap- ping, fusiform-elliptical to ellipsoid, hyaline, 1 septum, constricted at the median septum, straight or slightly curved towards the apex, thin-walled, with two guttules in each cell, smooth-walled. Asexual morph: Undetermined.

Culture characters: Colonies on MEA reaching 20 mm diam. after 4 weeks at 25 °C. Culture from above, black, radiating, wrinkled, folded, margin undulate, dense, flat or umbonate, and slightly covered with grey aerial mycelium; reverse black with radiating, brown mycelium.

Material examined: Thailand, Chiang Rai Province, on dead stems of Clematis subumbellata, 20 March 2017, C. Phukhamsakda, CMTH11 (MFLU 17–1475, holotype); ex- type living culture, MFLUCC 17–2067.

Host: Clematis subumbellata—(This study).

Distribution: Thailand—(This study).

GenBank accession numbers: LSU: MT214619; SSU: MT226730; ITS: MT310663; tef1: MT394674; rpb2: MT394722.

Notes: The novel species resembles other genera in Plec- tosphaerellaceae (e.g. Fuscohypha and Plectosphaerella) by its coriaceous ascomata and fusiform-elliptical to ellipsoid, 1 septum ascospores (Carlucci et al. 2012; Giraldo et al. 2019; Phookamsak et al. 2019). The species has unique characters such as paraphyses and spathulate, simple pedicel asci. Moreover, Fuscohypha and Plectosphaerella are phylogenetically not closely related (Fig. 114).

Fig. 114 The best scoring RAxML tree with a final likelihood value of − 23259.637010 of ITS, LSU, tef1 and rpb2 sequence data for Plectosphaerellaceae. The topology and clade stability of the combined gene analyses was compared to the single gene analyses. The tree is rooted at Monilochaetes infuscans (CBS 379.77 and CBS 869.66). The matrix had 1093 distinct alignment patterns, with 13.22% of undetermined characters and gaps. Estimated base frequencies were as follows; A = 0.224235, C = 0.297727, G = 0.281301, T = 0.196738; substitution rates AC = 0.820050, AG = 1.988895, AT = 1.053617,   CG = 0.783458,    CT = 5.160854,    GT = 1.000000; gamma distribution shape parameter α = 0.2928059. The new species in this study are indicated in blue. Bootstrap values (BS) greater than 50% BS (maximum likelihood (left); maximum parsimony (middle)) and Bayesian posterior probabilities (BYPP, right) greater than 0.90 are given at the nodes. Hyphens (-) represent support values less than 50% BS/0.90 BYPP. Thick branches represent significant support val- ues from all analyses (BS ≥ 70%/BYPP ≥ 0.95) at the genus level

Fig. 115 Xenoplectosphaerella clematidis (MFLU 17–1475, holo- type). a Appearance of ascomata on Clematis subumbellata. b Close up of ascoma on host substrate. c Vertical section through ascoma. D Peridium. e Paraphyses (in cotton blue). f, g Asci. hj Ascospores. k, l Culture characteristics on MEA. Scale bars: b = 100 µm, c = 50 µm, dg = 20 µm, hj = 10 µm