Apiospora pseudogarethjonesi Z.L. Tun, sp. nov.                                                                         

Index Fungorum number: IF 902649, Facesoffungi number: FoF XXX  Fig. 1 and Fig. 2

Etymology: Refers to the morphological similarity with Apiospora garethjonesii

Holotype: MFLU24-0011

Saprobic on dead bamboo branch. Sexual morph: Stromata 400 – 678 μm high, scattered to gregarious, partly immersed, becoming erumpent to superficial, raised, dark brown, in linear rows, with a slit-like opening, multi-loculate. Ascomata 210 – 235 μm high, 282 – 310 μm diam (x̄ = 222.5 × 297.7 μm, n = 5), perithecial, arranged in rows, clustered, gregarious, with 3 – 5 perithecia forming groups immersed in stromata to erumpent through host surface, ellipsoidal to subglobose, dark brown, membranous. Ostiole present. Peridium 2 – 7 μm wide, with two layers; outer layer composed of dark brown, thick cells of textura angularis; inner layer white, thin, with textura angularis. Hamathecium composed of dense paraphyses, 4 – 7 μm wide, filamentous, longer than asci. Asci 52 –70 × 19 – 16 μm (x̄ = 58.50 × 16.26 μm, n = 20), 8-spored, unitunicate, clavate, with a short pedicel, apically rounded. Ascospores 20 – 25 × 8 – 10 μm (x̄ = 24.48 × 8.8 μm, n = 20) 1-septate, ellipsoidal, curved at the lower cell, with many guttules, hyaline, smooth-walled, thick gelatinous sheath 8–7 μm wide. Asexual morph: On PDA, Hyphae 2.5 – 4 μm in diameter, hyaline, septate, branched. Conidiophores reduced to the conidiogenous cells. Conidiogenous cells 4 – 6 μm × 3 – 5 μm (x̄ = 5.05 μm × 3.95 μm, n = 20), aggregated in clusters on hypha, pale brown, ampuliform or cylindrical. Conidia 15 – 20 μm long (n = 20), brown, smooth, globose to subglobose in surface view, and 15 – 21 μm long (n = 20), lenticular, with a paler equatorial slit in side view.

Culture characteristics: Colonies on PDA reaching 6 cm diam. after 6 days at 27 °C, from above white to white yellow radiating outwards, dense, circular, flattened with smooth surface; reverse yellow-white.

Material examined: Thailand, Chiang Mai Province, forests around the Mushroom Research Center, on dead branches bamboo, 14 November 2022, ZL Tun, M2 (MFLU 24-0011, holotype); ex-type living culture (MFLUCC 24-0320).

Notes: Apiospora pseudogarethjonesii (MFLUCC 24-0320) clustered with A. garethjonesii (NR_154736, JHB004), A. mytilomorpha (DAOM 214595) and A. subrosea (LC7292) (Fig. 1). We compared the morphology and genetic distances of A. pseudogarethjonesii (MFLUCC 24-0320) with A. garethjonesii (NR_154736, JHB004), A. mytilomorpha (DAOM 214595) and A. subrosea (LC7292). Apiospora pseudogarethjonesii have larger ascomata (210–235 × 282–310 μm) compared to A. garethjonesii (177–235 × 141–232 μm) (Dai et al. 2016). The asci of A. pseudogarethjonesii are smaller (52 – 70 × 19–16 μm) compared to A. garethjonesii (125–154 × 35–42 μm). In addition, A. pseudogarethjonesii has smaller ascospores (20 – 25 × 8 – 10 μm) compared to A. garethjonesii (30 – 42 × 11 – 16 μm). Apiospora pseudogarethjonesii has a thick gelatinous sheath; however, A. garethjonesii has a faint gelatinous sheath (Dai et al. 2016). We also compared the asexual morphology of the two species. Apiospora pseudogarethjonesii has shorter conidiogenous cells (4 – 6 × 3 – 5 μm) compared to A. garethjonesii (6 − 20 × 3 – 7 μm) (Feng et al. 2021). The sexual morphs of A. pseudogarethjonesii and A. mytilomorpha have not been reported; therefore, we only compared the asexual morphs. The conidia of A. mytilomorphum are dark brown, fusiform or navicular, while the conidia of A. pseudogarethjonesii are brown, smooth, globose to subglobose (Wang et al. 2018). Apiospora mytilomorphum and A. pseudogarethjonesii also differ in the size of their conidia (15 – 20 × 15 – 21 μm vs. 20 – 30 × 6 – 8.5 μm, respectively). The sexual morphs of Apiospora pseudogarethjonesii and A. subrosea have not been reported; therefore, we only compared the asexual morphs. Apiospora pseudogarethjonesii has larger conidia (15 – 20 × 15 – 21 μm) compared to A. subrosea (12.0 – 17.5 × 9.0 –16.0 μm) (Wang et al. 2018).

The inter-species genetic distances between Apiospora pseudogarethjonesii (MFLUCC 24-0320) and A. garethjonesii (HKAS 96289) were 2.24% different across ITS (579 bp) and no difference in the LSU sequences. Apiospora garethjonesii lacks β-tub and tef-1α sequences and could not be compared. Apiospora pseudogarethjonesii (MFLUCC 24-0320) and A. mytilomorpha (DAOM 214595) differ by 2.1% across ITS (7/323bp), and A. mytilomorpha lack LSU, β-tub and tef-1α to compare. Apiospora pseudogarethjonesii (MFLUCC 24-0320) and A. subrosea (LC7292) were 1.58% different across ITS (569 bp), 1.57% across tef-1α (570 bp), 3% across tef-1α (401 bp) and were similar based on LSU sequences. As a result of the phylogenetic and morphological comparisons, A. pseudogarethjonesiiis is described as a new species.

Fig. 1  Apiospora pseudogarethjonesii (MFLU 24-0011, holotype); a Substrate. b Appearance of stromata on bamboo. c Vertical section of stroma. d Peridium wall. e Paraphyses. f, g Asci. h–l Ascospores. m Ascospore with thick gelatinous sheath in Melzer’s reagent. n Germinated ascospore. o, p Front and reverse colony on PDA. q Colony on PDA-producing conidia masses. r Conidiogenous cells give rise to conidia. s, t Dentate conidia. Scale bars: b, c = 200 μm. d, e = 4 μm. f, g= 20 μm. h–n = 20 μm. r–t = 20 μm.

Fig. 2  Phylogram generated from ML based on the combined ITS, LSU, tef-1α and β-tub sequences of representative Apiospora taxa. Arthrinium caricicola (CBS 145127) was used as the outgroup. Bootstrap support values (ML ≥69%) and Bayesian posterior probabilities (PP ≥0.95) are given at respective nodes. Hyphens (-) represent support values below 69% (ML) and 0.95 (PP). The type strains are bold, and the new isolate is red.

Fig. 2  Continued.