Shrungabeeja kudremukhensis O.P. Sruthi & Rajeshk., sp. nov.

Index Fungorum Number: IF 901423; Mycobank number: MB 901423; Facesoffungi number: FoF 16041; Figs. 1, 2

Etymology – Name refers to the place, where the fungus was collected, Kudremukh.

Holotype – AMH 10634

Saprobic on decaying bamboo culms in terrestrial habitat. Sexual morph: Not observed. Asexual morph: hyphomycetous. Colonies effuse, brown to dark brown. Mycelium partly superficial, partly immersed in the substratum, composed of branched, septate, pale brown, smooth-walled hyphae. Conidiophores macronematous, mononematous, erect,straight or flexuous, unbranched, smooth, thick-walled, 157.5–429 × 7–15 μm (−x=289 × 10 μm, n=15) 4 –5 μm wide at the apex, 3–5 septate. Conidiogenous cells monoblastic, terminal, determinate or percurrent, pale brown to brown, smooth, 10.5–20 × 6–8 μm. Conidia solitary, dry, acrogenous, globose to sub globose, aseptate, hollow, pedicellate, with 3–5 filiform appendages in the anterior region continuous or sometimes 3–25 septate, verruculose at basal part around the attachment and smooth over rest of the conidial body, pale brown to brown, 30.5–55 × 44–70 μm (−x=44 × 57 μm, n=30) broader than long. Appendages filiform, continuous or sometimes 3–25 septate, smooth, pale brown to brown, 156–463 × 3–4 μm (−x=313 × 3.6 μm, n=30).

Culture characteristics – Colonies on PDA attaining 3.5–4.8 cm diam. after 20 days at room temperature (25 °C), cottony, grey, with entire margin, reverse almost black, no pigment produced, sporulating. Conidia 30.4–54 × 46–70 µm (x̄= 45 × 56 µm, n = 30). Appendages 4–5, 593–1125 × 3–4 μm (x̄=744.52 × 3.2 µm, n=30).

Material examined – India, Karnataka, Kudremukh (13° 08′ 28″ N, 75° 15′ 75″ E), on dead culm of Bambusa sp. (Poaceae), 17 September 2022, Sruthi O. P. and Rajeshkumar K. C. (AMH 10634, holotype); ex-type NFCCI 5693.

GenBank numbers – NFCCI 5693: ITS: OR815994, LSU: OR815980, SSU: OR815981, tef1-α: OR824934.

Notes – Phylogenetic analyses of combined SSU, LSU, ITS and tef1-α gene region sequence data showed that Shrungabeeja kudremukhensis (NFCCI 5693) is related to Shrungabeeja and forms a distinct linage with 93% ML-BS, 86% R-BS and 0.94 BYPP values (Fig. 3). Shrungabeeja species have dark conidiophores with integrated, terminal, monoblastic, determinate or percurrent conidiogenous cells and lageniform, acrogenous, solitary, aseptate, globose or turbinate conidia, with filiform or horn-like appendages (Rao and Reddy 1981). There are no known sexual morphs available for this genus. Shrungabeeja kudremukhensis shares some similarities to Shrungabeeja appendiculata in its conidial size and appendage length. However, our new species (30.5–54 × 46–70 μm conidia) has larger conidia than S. appendiculata (30.5–54 × 46–70 μm conidia). Appendage length of S. appendiculata (100–360 μm, 4–21 septate) is shorter than S. kudremukhensis, which has very long filiform appendages (156–463 μm long in natural substrate and 593–1125 μm long in culture media, aseptate to 3–25 septate). Additionally, our new species has longer conidiophores (157.5–429 × 7–15 μm) than any other reported Shrungabeeja species. Even though, S. kudremukhensis has some overlapping morphological characters with S. appendiculata in its conidial dimension, phylogenetic analysis delineated it as a separate lineage. Based on the above morphological and molecular characteristics, Shrungabeeja kudremukhensis is introduced as a new species and placed in Tetraplosphaeriaceae.

Figure 1 – Shrungabeeja kudremukhensis (AMH 10634, stereomicroscopy holotype) a Conidia on host. b Conidiophore with conidial attachment in vivo. c–d Conidia with appendages in vivo. e Conidial body showing internal mycelia. f ex-type living culture on MEA (obverse). g Conidia and conidiophores in culture (in vitro). Scale bars: a=100 μm, b–d=50 μm, e=10 μm, g=50 μm

Figure 2 – Shrungabeeja kudremukhensis (AMH 10634 SEM from holotype) a Conidia attached on conidiophores. b Conidial from top view. c Conidial base shown prominent verruculose ornamentation around the base. d–e Smooth conidial body in zoom, f–l Conidial variation. Scale bars: a=10 μm, b, c=2 μm, d–e=10 μm, f–l=10 μm

Figure 3 – Phylogenetic tree obtained from an IQ-TREE analysis of species from Tetraplosphaeriaceae based on combined LSU, ITS, SSU, and tef1-α sequences. Related sequences are taken from Phookamsak et al. (2022) and additions according to the BLAST searches in NCBI. 45 sequences are included in the analysis which comprises 3385 characters (1462 characters for LSU, 588 characters for ITS, 1366 characters for SSU, 918 characters for tef1-α) after alignment. The evolutionary model SYM+I+G4 was used for IQ tree analysis. RAxML analysis and Bayesian inference were implemented with the GTR+I+G model. Muritestudina chiangrainensis (MFLUCC 17-2551) was used as the outgroup taxa. The best-scoring IQ tree with a final likelihood value of − 11,834.995 is presented. The matrix had 728 distinct alignment patterns, with 28.55% of undetermined characters or gaps. Estimated base frequencies were as follows: A=0.250, C=0.250, G=0.250, T=0.250; substitution rates: AC=3.75859, AG=4.80170, AT=2.27679, CG=1.64189, CT=10.27537, GT=1.00000; gamma distribution shape parameter α=0.569. Branch support values from 1000 non-parametric bootstraps for IQ-TREE (ML-BS) and RAxML (R-BS) and posterior probability values from the Bayesian analysis (BYPP) are shown at the nodes. Bootstrap support values for ML equal to or greater than 50% are given above the nodes. Bayesian posterior probabilities (BYPP) equal to or greater than 0.90 are given above the nodes. Extype strains are in bold and newly generated sequences as well as new combinations are in blue bold