Asterinales M.E. Barr ex D. Hawksw. & O.E. Erikss.

MycoBank number: MB 90461; Index Fungorum number: IF 90461; Facesoffungi number: FoF 07605.

Asterinales contains epifoliar fungi which have superficial mycelium forming a network on host plants, 1-celled appressoria, with a star-like opening to the thyriothecium. The order was revised by Hongsanan et al. (2014b), however, its classification is unclear due to insufficient sequence data. Sequence data of Asterinales clustered in two unrelated clades in phylogenetic trees (Ertz et al. 2016; Hyde et al. 2016b; Liu et al. 2017). The clade containing the type species Asterotexis cucurbitacearum was treated as Asterotexales (Ertz et al. 2016). However, Hyde et al. (2016b) synonymized it under Asterinales sensu stricto because most Asterinales strains cluster in this clade. The other clade, including species of Parmulariaceae were treated as Asterinales sensu lato (Liu et al. 2017). Parmulariaceae was transferred to its own order Parmulariales by Dai et al. (2018).

Although the type species Asterina melastomatis and a few other Asterinales like taxa fell within the clade Asterinales sensu lato (Ertz et al. 2016; Hyde et al. 2016b), we did not include these sequence data in our analysis. This is because Asterinales-like taxa forming in the Asterinales sensu lato need to be rechecked since other hyphomycetous strains were added into this clade, thus, there is possibility that these sequence data are not Asterinales. Thyrinulaceae is introduced to accommodate a clade sister to Parmulariales (= Asterinales sensu lato) with Thyrinula as generic type based on the rules of nomenclatural priority. Hongsanan et al. (2014b) synonymised Lembosiaceae under Asterinaceae, however, adding more sequence data for Lembosia (Fig. 5) indicates that Lembosia should be raised to a family in Asterinales.

By considering phylogenetic trees (Fig. 5), we retain Lembosiaceae in Asterinales and introduce Morenoinaceae and Neobuelliellaceae to accommodate the clades of Morenoina and Neobuelliella, respectively. Based on morphology and phylogeny, the current Asterinales comprises eight families. The classification of Asterinales is questionable and needs more morphological and molecular data to clarify its phylogenetic relationship. The divergence time for Asterinales is estimated as 221 MYA (stem age, Hongsanan et al. 2020).

Accepted families: Asterinaceae, Asterotexaceae, Hemigraphaceae, Lembisiaceae, Melaspileellaceae, Morenoinaceae, Neobuelliellaceae and Stictographaceae.

The order Asterinales was introduced by Barr (1976) without a Latin diagnosis and was subsequently validated by Hawksworth and Eriksson (1986). Hyde et al. (2013) accepted three families in the order, namely Asterinaceae, Aulographaceae, and Parmulariaceae. Species of Asterinales develop pigmented, superficial hyphae with appressoria and superficial thyriothecia, with elongate or round scutella, that open by slits or star-like fissures. Asci are globose to subglobose, bitunicate and usually include eight, 1-septate, brown, ellipsoid ascospores. Wu et al. (2011) suggested that Parmulariaceae should be included in Asterinales, this was followed by Hyde et al. (2013). In contrast to species of Parmulariaceae with superficial to immersed hypostroma, shield- or star-like, hypostroma composed of cells of textura prismatica and non-appressoriate hyphae, species of Asterinales are characterized by hyphae usually with appressoria, flattened thyriothecia with radially arranged cells in the upper wall, a poorly developed base, star-like or sometimes slit-like openings (Hofmann 2010; Hosagoudar 2012; Hyde et al. 2013).

Taxonomy

Asterinales M.E. Barr ex D. Hawksw. & O.E. Erikss., Syst. Ascom. 5(1): 177 (1986)
Parasites or saprobes on leaves, stems and stalks of higher plants. Superficial hyphae absent or superficial, with or lacking appressoria, with numerous infection strategies. Sexual state: Thyriothecia of various shapes, dehiscing to form fissures for the release of asci. Asci 8-spored, bitunicate, globose to subglobose. Ascospores hyaline to brown, mostly conglobate, but ranging to cylindrical. Asexual states: coelomycetous states with pycnidia or pycnothyria and hyphomycetous states then gelatinous, pale.

Notes: Hawksworth and Eriksson (1986) validated the order Asterinales which had been invalidly introduced by Barr (1976) without a Latin diagnosis. The Asterinales is based on the type family Asterinaceae and is characterized by superficial, thyriothecial, dimidiate, black thyriothecia, with radial hyphae and often appessoria, appressed hyphae, globose-subglobose asci and 1-septate, brown mostly conglobate ascospores (Hosagoudar 2012; Hyde et al. 2013). Molecular analyses were used to confirm that Asterinales can be included in Dothideomycetes (Hofmann et al. 2010; Wu et al. 2011; Hyde et al. 2013; Boonmee et al. 2014; Wijayawardene et al. 2014) and presently includes a single family, Asterinaceae (Fig. 1 ).

Fig. 1 RAxML maximum likelihood phylogenetic tree (LSU). Numbers to the left of the nodes are RAxML value expressed from 1,000 repetitions with values above 50 % shown. Numbers to the right of the nodes are Bayesian posterior probabilities, with values above 90 % shown. Strain numbers are indicated after species names. New sequence data are in red and other ex-types are in bold.

Fig. 5 Phylogram generated from maximum likelihood analysis (RAxML) of Asterinales based on LSU sequence data. Maximum likelihood bootstrap values equal to or greater than 70%, Bayesian posterior probabilities equal to or greater than 0.90 (MLBS/PP) are given at the nodes. Isolate numbers are noted after each species name. The tree is rooted to Venturia inaequalis (ATCC 60070) and Venturia populina (CBS 256.38). Newly sequence data generated in this study are in blue. Ex-types are indicated in bold. Hyphen (-) represents sup- port values less than 70% MLBS and 0.90 PP

Families