Holmiellaceae
Holmiellaceae Maharachch. & Wanas., MycoBank: MB 837549
Saprobic on dead wood in terrestrial habitats. Sexual morph: Ascomata apothecial, solitary, superficial, exposing a velvet hymenium when mature, globose, black. Exciple pseudoparenchymatous. Hamathecium composed of filamentous, septate, branched, hyaline, anastomosing pseudoparaphyses, forming a dark brown epithecium above the asci. Asci 8-spored, bitunicate, with an ocular chamber. Ascospores 2–3-seriate overlapping, clavate to ellipsoidal, 1-septate, brown to dark brown. Asexual morph: corniculariella-like. Conidiomata pycnidial, globose, black, superficial or immersed in cultures. Conidiophores branched, hyaline, septate. Conidiogenous cells integrated, subulate, hyaline. Conidia straight to curved, hyaline. Chlamydospores may present.
Type genus: Holmiella Petrini, Samuels & E. Müll.
Notes—This new order Holmiellales and new family Holmiellaceae are introduced for a lineage of saprobic fungi that were previously placed in the monotypic order Patellariales. The family Patellariaceae was introduced by Corda (1839) to accommodate the genera Cryptodiscus Corda and Mellitiosporium Corda (Kutorga and Hawksworth 1997; Yacharoen et al. 2015). Hongsanan et al. (2020b) reported that Patellariales was around evolved between 31 Mya (crown age) and 276 Mya (stem age). Patellariaceae is heterogenous family characterised by apothecial fruiting bodies, and in the literature, taxa belonging to the group have been described in various families and orders (Nannfeldt 1932; Luttrell 1951; Reid and Pirozynski 1966; Barr 1979; Samuels and Müller 1979; Haffellner 1979; Petrini et al. 1979; Eriksson 1981; Eriksson and Hawksworth 1993; Boehm et al. 2009; Schoch et al. 2009; Jones and Pang 2012). The arrangement based on Yacharoen et al. (2015) recognised 14 genera, while a recent outline by Wijayawardene et al. (2020) accepted 21 genera within the Patellariaceae. However, most of these genera lack sequence data, and therefore, natural classification of Patellariaceae within the Dothideomycetes is still incomplete. The phylogenetic analysis of combined SSU, LSU, 5.8S, RPB2 and TEF sequences for species of Holmiella, revealed that the genus is closely related to Botryosphaeriales, Catinellales and Homortomycetaceae, refuting earlier suggestions of its placement in Patellariaceae (Yacharoen et al. 2015; Pem et al. 2018). Holmiella was erected by Petrini et al. (1979) to accommodate Triblidium sabinum De Not. (= Holmiella macrospora) designated by De Notaris in 1867. The type species Holmiella sabina (De Not.) Petrini, Samuels & E. Müll. inhabits as an endophyte or saprobe within needles and wood of Juniperus species (Holm and Holm 1977; Kutorga and Hawksworth, 1997; Eriksson 2014). The new order Holmiellales has a stem age at 97 million of years and has the same common ancestor with new orders Homortomycetales at 120 million of years. In the past Holmiella sabina has been assigned to diverse genera (Kutorga and Hawksworth 1997). Later the second species, H. macrospora (Bonar & E.K. Cash) Kutorga & D. Hawksw., was added to the genus by Kutorga & Hawksworth (1997); this species inhabits bark of Calocedrus decurrens (Torr.) Florin in the USA that was introduced as Tryblidiella macrospora Bonar & E.K. Cash by Cash (1945). Pem et al. (2018) introduced Holmiella junipericola Pem et al. and H. juniperi-semiglobosae Pem et al., thus the genus presently comprises four species. Based on evidence from phylogeny and morphology in our assessments, we suggest that the species of Holmiella do not belong to Patellariales, and therefore the new order Holmiellales and the new family Holmiellaceae are introduced herein. Species of Holmiella have apothecial ascomata which are initially enclosed in host parenchyma, and subsequently crack open to become finally exposed through a wide, irregular hymenium.
Reference:
Maharachchikumbura SSN, Wanasinghe DN, Cheewangkoon R, Al‑Sadi AM. 2020. Uncovering the hidden taxonomic diversity of fungi in Oman. Fungal Diversity. https://doi.org/10.1007/s13225-020-00467-1
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