Valsaria tectonae Bundhun & Jayaward., 2023

Bundhun, Digvijayini, Jayawardena, Ruvishika S. & Camporesi, Erio, 2023, Introducing Nigrograna italica sp. nov. (Nigrogranaceae) from Corylus avellana and Valsaria tectonae sp. nov. (Valsariaceae) from Tectona grandis, Phytotaxa 618 (2), pp. 103-119 : 113

Valsaria tectonae Bundhun & Jayaward. , sp. nov. ( FIGURE 6 )

Index Fungorum number: IF 901099, Facesoffungi number: FoF 14855

Etymology: The specific epithet refers to host Tectona grandis from which the fungus was collected.

Holotype: MFLU 23-0140

Saprobic on dead twigs of Tectona grandis (Lamiaceae) . Sexual morph: Stromata pseudostromatic, scattered on the host, rarely aggregating to groups of 2–3, erumpent from bark, pustular, conical to subglobose, with flattened base, enclosed by pseudoparenchymatous crust on the top and at the sides. Ectostroma forming sub- or inversely stellate structures of often 4–5 greyish or black tubercular sections, tissue beneath the crust pseudoparenchymatous, tissue surrounding ostiolar necks and at stromatal base prosenchymatous, dark grey, soft, fusing with host tissue. Ostiolar openings inconspicuous at the surface. Ascomata 200–500 µm high (excluding ostiolar neck), 200–400 µm diam. (x̅ = 360 × 295 µm, n = 5), arranged in valsoid configuration, 5–7 per individual cluster, monostichous, vertical to oblique, perithecial, subglobose to flask-shaped, ostiolate. Ostiolar necks cylindrical, long, converging, often fusing, lined with hyaline periphyses. Peridium 20–30 µm thick, comprising two regions; outer region 5–10 µm thick, made up of brown, compressed cells fusing with the host tissue; inner region 12–20 µm thick, composed of 5–7 layers of thin-walled, hyaline cells of textura angularis to textura prismatica; turning to slightly olivaceous-grey in 3% KOH. Pseudoparaphyses 2–4 µm wide, abundant, filiform, septate, unbranched, apically free. Asci 80–130 × 8–13 µm (x̅ = 98.8 × 9.9 µm, n = 20), regularly 8-spored, bitunicate, with no conspicuous fissituncate dehiscence, cylindrical, short-pedicellate, rounded apex with conspicuous ocular chamber and containing a cylindrical- to barrel-shaped ring, staining in Congo Red. Ascospores 14–19 × 5–9 µm (x̅ = 16.2 × 7.7 µm, n = 30), uniseriate, ellipsoid, hyaline and guttulate when immature, dark brown and guttules absent at maturity, centrally septate, septum thick and darker than cells, not constricted or slightly constricted at the septum, with conical to broad rounded ends, surface tuberculate to tuberculate-reticulate, without sheath or appendages. Asexual morph: Not observed.

Culture characteristics:—colonies on PDA reaching 20 mm diam. after 1 week at 25 °C. Colony from above dense, circular, with a thick mat of aerial hyphae, white to greyish or pale brown, fimbriate, radially furrowed; reverse off-white to yellowish, with grey spots.

Material examined:— Thailand, Nan Province, on dead twigs of Tectona grandis (Lamiaceae) , 25 September 2022, D. Bundhun, Nan2 ( MFLU 23-0140 , holotype), ex-type living culture MFLUCC 23-0085.

Notes:—strain MFLUCC 23-0085 clusters with the type strain of V. neotropica (CBS 139064) with 100% ML, 1.00 BYPP support ( FIGURE 3 ). Our collection morphologically resembles V. neotropica (CBS 139064) in stromatic and ascomatal features ( Jaklitsch et al. 2015, this study). The pseudoparaphyses are also unbranched and apically free. The asci are almost similar in size and no conspicuous fissitunicate dehiscence is equally observed in our collection, similar to those of V. neotropica (CBS 139064) ( Jaklitsch et al. 2015, this study). The main differences between strain MFLUCC 23-0085 and V. neotropica (CBS 139064) are in the peridium structure and ascospore morphology. The peridium of strain MFLUCC 23-0085 contains two regions, with an outer region of brown, compressed cells and an inner region made up of 5–7 layers of hyaline cells of textura angularis to textura prismatica ( FIGURE 6 ). Also, it turns to slightly olivaceous-grey in 3% KOH. The peridium of V. neotropica (CBS 139064) has been reported to comprise pale brown compressed cells; no report on its reaction with KOH has been given ( Jaklitsch et al. 2015). In addition, the ascospores of our collection are smaller (14–19 × 5–9 µm) as compared to those of V. neotropica (CBS 139064) ((17.7–)19.0–22.5(–27.8) × (7.7–)8.3–10.7(–13.7) µm; Jaklitsch et al. 2015). The ascospore surface ornamentation of the two strains also differ in that isolate MFLUCC 23-0085 comprises ascospores with tuberculate to tuberculate-reticulate surface while those of V. neotropica (CBS 139064) are finely tuberculate ( Jaklitsch et al. 2015). Comparison of the genetic markers (based on aligned untrimmed dataset, excluding gaps) also reveals significant differences between strain MFLUCC 23-0085 and V. neotropica (CBS 139064); there are 3.1% bp differences in ITS region, while 5.3% and 2.9% bp differences in rpb2 and tef1, respectively. The PHI test also resulted in a threshold exceeding 0.05 (Фw = 0.929), indicating no recombination event has occurred ( FIGURE 4 ). Therefore, based on morphological as well as genetic variation between the strains MFLUCC 23-0085 and V. neotropica (CBS 139064), we identify our collection as a new taxon, herein introduced as V. tectonae . This novel Thai strain is isolated from Tectona grandis for which it is previously unknown ( Doilom et al. 2017).

Figures

FIGURE 3. Phylogram generated from maximum likelihood analysis based on combined SSU, LSU, ITS, rpb2 and tef1 sequence data for Valsariaceae. The tree is artificially rooted with Tubeufia abundata (MFLUCC 17-2024) and T. freycinetiae (MFLUCC 16-0252). Bootstrap support values for ML (≥70%) and BYPP (≥ 0.90) are respectively given above or below the branches. Type strains are in bold. The newly generated sequence is indicated in bold red.

FIGURE 4. PHI test result for Valsaria, using LogDet transformation and splits decomposition. The new taxon is illustrated in red.

FIGURE 6. Valsaria tectonae (MFLU 23-0140, holotype). a, b Ectostroma on host. c Transverse section at the ostiolar and ascomatal levels. d, e Vertical sections of stroma. f Periphysate ostiolar neck. g, h Vertical sections of peridium (h in 3% KOH). i Pseudoparaphyses (in Congo Red). j, k Asci. l Apex of an ascus with apical ring (in Congo Red). m–p Immature and mature ascospores. q Upper side of culture on PDA. r Reverse side of culture on PDA. Scale bars: a = 1 mm, b, e = 200 µm, c, f = 100 µm, d = 500 µm, g, h = 20 µm, i, l = 5 µm, j, k = 30 µm, m–p = 10 µm.