Scolecohyalosporium thailandense Phookamsak & Hongsanan, 2023

Phookamsak, Rungtiwa, Hongsanan, Sinang, Bhat, Darbhe Jayarama, Xu, Jianchu, Mortimer, Peter E., Suwannarach, Nakarin, Kumla, Jaturong, Dawoud, Turki M. & Lumyong, Saisamorn, 2023, Scolecohyalosporium thailandense sp. nov. (Parabambusicolaceae, Pleosporales) collected on Imperata sp. (Poaceae) in northern Thailand, Phytotaxa 594 (4), pp. 267-282 : 275

Scolecohyalosporium thailandense Phookamsak & Hongsanan , sp. nov. FIGURE 2

Index Fungorum number: IF 900245; Facesoffungi number: FoF 14015

Etymology: The specific epithet “ thailandense ” refers to the locality in Thailand, where the holotype was collected.

Holotype: MFLU 11-0164

Saprobic on dead culm of Imperata sp. (Poaceae) . Sexual morph Ascomata 180–250 μm high (including papilla), 145–370 µm diam., scattered solitary, semi-immersed to erumpent through the host tissue, visible as a black, shiny knob on host surface, subglobose to ampulliform, or irregular in shape, uni-loculate, glabrous, with a central, rounded to truncate ostiole, perched on a subconical to mammiform apical papilla, filled with hyaline periphyses. Peridium 10–30 μm wide, of equal thickness, composed of several layers of flattened, dark brown pseudoparenchymatous cells, paler towards the inner layers, arranged in textura angularis to textura prismatica. Hamathecium composed of numerous, 2–4 μm wide, filamentous, septate, broad, cellular pseudoparaphyses, constricted at the septa, tapering towards the apex, anastomosed above the asci, embedded in a hyaline gelatinous matrix. Asci 138–160(–170) × 7–10 μm (x̅ = 153.7 × 9.1 μm, n = 25), 8-spored, bitunicate, cylindrical to subcylindric-clavate, subsessile to short pedicellate, apically rounded, with subconical ocular chamber clearly visible in the immature state. Ascospores (135–)140–160(–166) × 2–3 μm (x̅ = 150.7 × 2.8 μm, n = 15), overlapping, parallelly to spirally arranged, filiform, tapering towards the lower cell, pale yellowish to yellowish, curved, smooth-walled, with 15–25 non-constricted septa, lacking a mucilaginous sheath. Asexual morph Undetermined.

Culture characteristics:— Colonies on PDA reaching 32–35 mm diam. after 2 weeks at room temperature (25– 35 °C). Colony dense, circular, slightly raised, to low convex, surface smooth, with edge entire, floccose; from above, dark brown to greenish-black; from below, black; not producing pigmentation on agar medium.

Material examined:— Thailand, Chiang Rai Province, Mae Fah Luang District, Doi Tung, on a dead culm of Imperata sp. (Poaceae) , 29 June 2010, R. Phookamsak, RP0044 ( MFLU 11-0164 , holotype!), ex-type living culture = MFLUCC 11-0128 .

Notes:— Based on the nucleotide BLAST search of ITS sequence, Scolecohyalosporium thailandense (strain MFLUCC 11-0128) showed the closest similarity with Multiseptospora sp. strain SFC20220920-G141 with 98.23% similarity (Identities = 556/566 bp, with one gap), and Scolecohyalosporium sp. GCR-2022a isolate KUMCC 21-0508 (97.96% similarity, Identities = 528/539 bp, with one gap) and isolate KUMCC 21-0507 (97.95% similarity, Identities = 525/536 bp, with one gap). Scolecohyalosporium thailandense (strain MFLUCC 11-0128) is also similar to the generic type, S. submersum strain HKAS 122242 (strain from type material), with 97.15% similarity (Identities = 478/492 bp, with one gap). The nucleotide BLAST search of LSU sequence indicated that S. thailandense (strain MFLUCC 11-0128) is similar to S. submersum strains HKAS 122242, KUMCC 21-0412, and KUMCC 21-0413 with 98.78% similarity (Identities = 809/819 bp, with one gap), and to Scolecohyalosporium sp. GCR-2022a (isolates KUMCC 21-0508 and KUMCC 21-0507) with 98.66% similarity (Identities = 808/819 bp, with one gap). The nucleotide BLAST search of TEF1-α sequence indicated that S. thailandense (strain MFLUCC 11-0128) has the closest similarity with Neomultiseptospora yunnanensis (strains KUN-HKAS 122240 and KUMCC 21-0411) with 97.04% similarity (Identities = 885/912 bp, with no gap), to Paramultiseptospora bambusae (voucher KUN-HKAS 122241B and KUN-HKAS 122241A) with 96.80% similarity (Identities = 907/937 bp, with no gap), and to Multiseptospora thailandica strain MFLUCC 12-0006 with 96.69% similarity (Identities = 818/846 bp, with no gap). Scolecohyalosporium thailandense is also similar to the generic type, S. submersum (strains KUN-HKAS 122242 and KUMCC 21-0413), with 96.63% similarity (Identities = 888/919 bp, with no gap).

Based on a nucleotide pairwise comparison, Scolecohyalosporium thailandense (strain MFLUCC 11-0128) differs from S. submersum (KUMCC 21-0412, ex-type strain) in 17/465 bp of ITS (3.65%), 10/850 bp of LSU (1.18%), and 33/928 bp of TEF1-α (3.56%). The species is also different from Scolecohyalosporium sp. GCR-2022a (isolates KUMCC 21-0508 and KUMCC 21-0507) in 10/465 bp of ITS (2.15%) and 11/818 bp of LSU (1.34%), while TEF1-α sequence data of Scolecohyalosporium sp. GCR-2022a (isolates KUMCC 21-0508 and KUMCC 21-0507) is unavailable.

Morphologically, Scolecohyalosporium thailandense can be easily distinguished from S. submersum (HKAS 122242, generic type) in having smaller sized ascomata (180–250 × 145–370 μm vs. 370–480 × 380–600 μm), asci (138–160(–170) × 7–10 μm vs. (200–)250–300(–370) × 7–9(–11) μm), and ascospores ((135–)140–160(–166) × 2–3 μm vs. (230–)260–285(–315) × 1.5–2.2 μm) ( Xie et al. 2022). Scolecohyalosporium thailandense also differs from S. submersum in having pale yellowish to yellowish and 15–25-septate ascospores, whereas S. submersum has hyaline and multi-septate ascospores (up to 20 septa) ( Xie et al. 2022). Multigene phylogenetic evidence also supported their distinctiveness ( FIGURE 1 ). Therefore, S. thailandense is introduced herein as the new species following the justification guidelines of Jeewon & Hyde (2016).

Figures

FIGURE 1. Phylogram generated by RAxML analysis based on a concatenated ITS, LSU, SSU, and TEF1-α sequence matrix representing the phylogenetic relationships of a novel species in Parabambusicolaceae and related families in suborder Massarineae. The tree is rooted with Melanomma pulvis-pyrius (CBS 124080). Bootstrap support values for ML and MP equal to or greater than 70%, and the Bayesian posterior probabilities equal to or higher than 0.95 PP are indicated at the nodes as ML/MP/PP. Support values lower than 70% and 0.95 were indicated by a hyphen (-). Ex-type strains are in black bold, and the newly generated strain is indicated in red bold.

FIGURE 2. Scolecohyalosporium thailandense (MFLU 11-0164, holotype). a. Appearance of ascomata on the host surface. b, c. Vertical section through ascomata. d. Section through peridium. e, f. Asci embedded in pseudoparaphyses. g. Ascus. h–k. Ascospores. Scale bars: b, c = 100 μm, d–k = 20 μm.