Nigrograna italica Bundhun, Camporesi & 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 : 111-112

Nigrograna italica Bundhun, Camporesi & Jayaward. , sp. nov. ( FIGURE 5 )

Index Fungorum number: IF 901098, Facesoffungi number: FoF 14854

Etymology: The specific epithet refers to the country, Italy, where the fungus was collected.

Holotype: MFLU 23-0139

Saprobic on dead branch of Corylus avellana (Betulaceae) . Sexual morph: Ascomata 330–520 µm high (including ostiolar neck), 250–350 µm diam. (x̅ = 405 × 313 µm, n = 5), solitary to aggregated, scattered along the host substrate, immersed, ostiolate, with ostiole not visible or at same level of bark or ostiolar neck protruding beyond bark level, often visible in bark fissures, usually lying obliquely or parallel to the host surface, sometimes upright, perithecial, globose to subglobose, surrounded by subiculum of brown hyphae (1–3 µm wide) at the base and sides which turn to olivaceous or olivaceous brown in 3% KOH. Ostiolar necks 100–240 µm high, cylindrical, papillate, black, eccentric or central, straight to oblique, apex flat and concolorous or slightly white, rarely papillate, lined with hyaline periphyses. Peridium 20–30 µm thick, turning olivaceous in 3% KOH, comprising 2 regions, outer region made up of 8–10 layers of thick-walled, brown cells of textura angularis, inner region comprising compressed, thin-walled, hyaline cells. Pseudoparaphyses 1–2.5 µm wide, numerous, trabeculate, branched, often branching in the middle or above the asci, rarely at the base, anastomosing, septate, almost same thickness from base to apex, rarely wider at the base, apex often tapering or sometimes slightly swollen. Asci 45–90 × 8–12 µm (x̅ = 67.5 × 10.4 µm, n = 20), 8-spored, bitunicate, fissitunicate, clavate to cylindric-clavate, short-pedicellate with knob-like to furcate base, rounded at the apex, with a small ocular chamber. Ascospores 13–19 × 3–7 µm (x̅ = 15.8 × 5.2 µm, n = 30), overlapping biseriate, especially at upper level, ellipsoid to broad fusiform, sub-hyaline to pale brown when immature, becoming golden brown to chocolate brown when mature, not or slightly darker in 3% KOH, straight to slightly curved, 3-euseptate, upper second cell generally slightly enlarged, septa darker than the cells, slightly constricted at the median septum, with conical to rounded ends, sometimes guttulate, smooth, no appendages or sheath. Asexual morph: not observed.

Material examined:— Italy, near Meldola, Forlì-Cesena Province, on dead aerial branch of Corylus avellana (Betulaceae) , 29 January 2022, E. Camporesi, IT 2741 ( MFLU 23 -0139, holotype).

Notes:—the strain MFLU 23-0139 forms a basal lineage to the N. obliqua strains with 98% ML, 0.99 BYPP support ( FIGURE 1 ). While nucleotide comparison (based on the aligned untrimmed dataset, excluding gaps) between the type, N. obliqua (CBS 141477), and our strain MFLU 23-0139 revealed insignificant differences in LSU and ITS, there were 2.2% and 1.8% base pair (bp) differences in rpb2 and tef1, respectively. Our strain (MFLU 23-0139) closely resembles N. obliqua (CBS 141477) in its obliquely located ascomata which often comprise an eccentric ostiolar neck ( Jaklitsch & Voglmayr 2016, this study), although they can also possess a central ostiolar neck similar to the strain N. obliqua (MFLUCC 14-0945) reported by Phukhamsakda et al. (2020). The ascomata are more visible in the bark fissures and they equally possess a subiculum of brown hyphae. The peridium of our new collection also changes colour, turning to olivaceous in 3% KOH, similar to that of N. obliqua (CBS 141477).

However, the major differences observed are that while the brown hyphae making the subiculum of N. obliqua (CBS 141477) remain unchanged in 3% KOH, the hyphae of MFLU 23-0139 darken and turn to olivaceous or olivaceous brown in 3% KOH. The pseudoparaphyses of N. obliqua (CBS 141477) are branched near the bases ( Jaklitsch & Voglmayr 2016), but in strain MFLU 23-0139, they are often branching in the middle or above the asci. The ascospores of MFLU 23-0139 are also morphologically slightly different than those of N. obliqua (CBS 141477); the ascospores of strain MFLU 23-0139 are smooth (even at immaturity) and their golden brown to chocolate brown colour may slightly darken in 3% KOH, while those of N. obliqua (CBS 141477) are faintly verruculose (more conspicuous at immature stage) and their colour remain unchanged in 3% KOH ( Jaklitsch & Voglmayr 2016). Moreover, the PHI test resulted in a threshold exceeding 0.05 (Фw = 0.908), suggesting no recombination event has occurred ( FIGURE 2 ). Based on the above evidence, as well as the guidelines of Chethana et al. (2021) and Pem et al. (2021), we introduce our new collection MFLU 23-0139 as a new species, Nigrograna italica .

Figures

FIGURE 1. Phylogram generated from maximum likelihood analysis based on combined SSU, LSU, ITS, rpb2 and tef1 sequence data for Nigrogranaceae taxa. The tree is artificially rooted with Occultibambusa bambusae (MFLUCC 13-0855) and O. kunmingensis (KUN- HKAS 102151). 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 2. PHI test result for Nigrograna, using LogDet transformation and splits decomposition. The new taxon is illustrated in red.

FIGURE 5. Nigrograna italica (MFLU 23-0139, holotype). a Dead branch of Corylus avellana. b Ascomata on host. c Vertical section of an ascoma in an oblique position with an eccentric ostiolar neck. d Vertical section of an ascoma with a central ostiolar neck. e Ostiolar neck. f, g Section of peridium (g in 3% KOH). h, i Subicular hyphae (i in 3% KOH). j–m Pseudoparaphyses (m showing the apex of a pseudoparaphysis). n–p Immature and mature asci. q–v Immature and mature ascospores (v in 3% KOH). Scale bars: a = 1 mm, b = 200 µm, c, d = 100 µm, e = 50 µm, f, g = 20 µm, h–m = 5 µm, n–p = 30 µm, q–v = 10 µm.