Pseudostomiopeltis Phookamsak & Hongsanan, in Hongsanan, Phookamsak, Bhat, Wanasinghe, Promputtha, Suwannarach, Sandamali, Lumyong, Xu & Xie, Frontiers in Cellular and Infection Microbiology 13(no. 1252387): 8 (2023)

Index Fungorum number: IF 900626; MycoBank number: MB 900626; Facesoffungi number: FoF 15864.

Etymology – The generic epithet “Pseudostomiopeltis” refers to the genus that resembles Stomiopeltis.

Epiphytic or saprobic on leaves and fruits. Sexual morphMycelium absence. Ascomata thyriothecial, black, solitary, gregarious, superficial, rounded, easily removed from the host surface. Upper wall composed of a thin layer of neatly arranged dark cells of textura angularis. Hamathecium lacking pseudoparaphyses. Asci 4-spored, bitunicate, fissitunicate, oblong to subglobose, with a minute pedicel. Ascospores uniseriate, hyaline, asymmetric, obovoid to ellipsoid, 1-septate, constricted at the septum, upper cell slightly broader than the lower cell (Adopted from ). Asexual morphMycelium absence. Conidiomata thyriothecial, superficial, scattered, or in a small group, hemispherical, dimidiate-scutate, uniloculate, with a central, pore-like ostiole. Upper wall composed of a thin layer, of brown, radiating cells, with loosely irregular lobed cells at the margin. Peridium composed of 1–2 strata of textura angularis. Conidiophores reduced to conidiogenous cells. Conidiogenous cells arising from the innermost wall cells of the conidiomata, hyaline, enteroblastic, phialidic, lageniform to ampulliform, determinate, discrete, smooth-walled, with minute channel and collarette. Conidia solitary, hyaline, ellipsoidal to oblong, slightly truncate at the base, with obtuse apex, aseptate, smooth-walled, occasionally with attached conidiogenous cell. Sporulation in vitro forming dense, brown, compact hyphae on OA medium, with cream spore masses. Conidiophores hyaline, cylindrical to subcylindrical, septate, branched or unbranched, smooth-walled. Conidiogenous cells hyaline, enteroblastic, phialidic, terminal and intercalary, cylindrical to subcylindrical, aseptate, smooth-walled, with minute channel and collarette. Conidia solitary, hyaline, subglobose to ellipsoidal to oblong, with obtuse ends, aseptate, smooth-walled.

Type species – Pseudostomiopeltis xishuangbannaensis Phookamsak, Hongsanan, Wanas. and Bhat

Notes –  re-circumscribed the genus Stomiopeltis based on morphological studies and divided the species of Stomiopeltis into two groups based on the difference in the types of upper wall cell arrangements. The first group included the type species (S. aspersa) that has non-radiating upper wall cells, composed of disorderly arranged, irregularly lobed pseudoparenchymatous cells, while the second group has radiating upper wall cells, somewhat obscured by the curving and twisting of the radiating hyphae and by the irregularly lobed cells, which may be termed as “meandering plectenchyma”.  mentioned that the second group should be placed in Microthyriaceae. The phylogenetic analyses conducted by  also showed that Stomiopeltis is polyphyletic due to S. betulae forming a clade within Microthyriales, while two Stomiopeltis-like species formed a clade with Tothia fuscella in Venturiales. The present phylogenetic analyses of a concatenated ITS and LSU sequence dataset demonstrated that our new isolate formed a well-resolved subclade with other Stomiopeltis sensu lato in PhaeothecoidiellaceaeMycosphaerellales. Besides, the type species of StomiopeltisS. aspersa, has not yet been sequenced, and hence the phylogenetic affinity of Stomiopeltis sensu stricto is still uncertain.

 re-examined the holotype of Stomiopeltis aspersa and provided an updated morphological description that is characterized by superficial, brown, reticulate hyphae, flattened, circular, brown, thyriothecia with an irregular central ostiole. The upper wall comprises brown, meandrous, compact hyphae, lacking a basal plate. Asci are 8-spored, ellipsoidal, short-pedicellate, with an ocular chamber and ascospores are overlapping 2–3-seriate, hyaline, cylindrical, 1-septate, not constricted at the septum, with the upper cell shorter and broader than the lower cell. Morphologically, our new isolate could not be compared with the type of S. aspersa because they form different morphs. However, the new isolate is clearly distinguished from S. aspersa by the absence of superficial, brown, reticulate hyphae that penetrate the host and form hemispherical, dimidiate-scutate thyriothecia. Additionally, the upper wall of the thyriothecia radiates, and the cells at the margin are loosely and irregularly lobed, while S. aspersa has a non-radiating upper wall composed of sinuous, irregularly lobed cells [Figures 20c, d in ]. Furthermore, S. phyllanthi which formed a clade with our new isolate, is also different from S. aspersa in lacking superficial, reticulate hyphae on the host and pseudoparaphyses (). Based on phylogenetic evidence and morphological distinctiveness with the type of Stomiopeltis, we introduced the new genus Pseudostomiopeltis to accommodate the new species, Ps. xishuangbannaensis, while Stomiopeltis phyllanthi is also transferred to the new genus as Pseudostomiopeltis phyllanthi comb. nov.

Figure 1 – Phylogram of the best-scoring maximum likelihood (ML) consensus tree based on a combined dataset (ITS and LSU) of Pseudostomiopeltis. The new species is indicated in blue, and the new combination species are indicated in green. Isolates from type materials are in bold. The ML ultrafast bootstrap and Bayesian PP values greater than 70% and 0.95 are shown at the nodes. The tree is rooted with Botryosphaeria fusispora (MFLUCC 10-0098) and Lasiodiplodia gonubiensis (CBS 115812).