Pseudomultiseptospora Phookamsak, Rajeshk., Karun. & Wijayaw., gen. nov.

Index Fungorum number: IF 559658; MycoBank number: MB 559658; Facesoffungi number: FoF 10840

Etymology – based on the morphological similarity with Multiseptospora.

Saprobic on grass. Sexual morph: Ascomata solitary to gregarious, scattered, immersed, visible as raised, black dots on host surface, uni-loculate, globose to subglobose, glabrous, ostiole, with minute papilla. Peridium inner layers comprise compressed, hyaline, cells of textura prismatica, outer layers comprising brown to dark brown cells of textura angularis. Hamathecium composed of dense, cellular pseudoparaphyses, septate, slightly constricted at the septa, anastomosing among the asci, embedded in a hyaline gelatinous matrix. Asci 8-spored, bitunicate, fissitunicate, broadly cylindric-clavate to clavate, subsessile to short pedicellate, apically rounded, with an indistinct ocular chamber. Ascospores overlapping 3–4-seriate, initially hyaline, becoming brown to dark brown at maturity, fusiform, with slightly rounded ends, slightly curved, septate, not constricted at the septa, smooth-walled, surrounded by thin, mucilaginous sheath, with small appendages at both ends.

Type species – Pseudomultiseptospora thysanolaenae (Phookamsak, Ariyawansa & K.D. Hyde) Phookamsak, Rajeshk., Karun. & Wijayaw.

Notes – The genus Multiseptospora Phookamsak & K.D. Hyde was introduced in Liu et al. (2015) to accommodate a single species M. thailandica Phookamsak & K.D. Hyde which was collected on Thysanolaena maxima Kuntze. The genus was accommodated in the Pleosporales genera incertae sedis (Liu et al. 2015). However, Tanaka et al. (2015) placed the genus Multiseptospora in Parabambusicolaceae based on its phylogenetic relationships. Li et al. (2016) introduced the second species M. thysanolaenae. Our multi-locus sequence analyses (Fig. 1) delineated that M. thysanolaenae distantly related to Multiseptospora sensu stricto. The morphological comparison of M. thysanolaenae with M. thailandica also supported their distant affinity. Therefore, we propose a new genus Pseudomultiseptospora, for M. thysanolaenae as Pseudomultiseptospora thysanolaenae.

Figure 1 – The best scoring RAxML tree for the combined ITS, LSU and tef1-α sequence data of Parabambusicolaceae and allied families is shown. The topology and clade stability of the combined gene analyses were not significantly different from the single gene analyses. The matrix had 1036 distinct alignment patterns with 19.45% undetermined characters and gaps. Estimated base frequencies were as follows; A=0.211898, C=0.289868, G=0.265372, T=0.232861; substitution rates AC=1.185503, AG=2.613342, AT=1.743890, CG=0.861391, CT=5.838493, GT=1.0; gamma distribution shape parameter α=0.648723. Bootstrap support for ML equal to or greater than 70%, Bayesian posterior probabilities (PP) equal to or greater than 0.88 are shown as ML/PP at the nodes. The tree is rooted to Melanomma pulivis-pyrius CBS 124080. The newly generated sequences are indicated in blue bold

Species