Tzeananiaceae, a new pleosporalean family associated with Ophiocordycepsmacroacicularis fruiting bodies in Taiwan

Abstract

The order Pleosporales comprises a miscellaneous group of fungi and is considered to be the largest order of the class Dothideomycetes. The circumscription of Pleosporales has undergone numerous changes in recent years due to the addition of large numbers of families reported from various habitats and with a large amount of morphological variation. Many asexual genera have been reported in Pleosporales and can be either hyphomycetes or coelomycetes. Phoma-like taxa are common and have been shown to be polyphyletic within the order and allied with several sexual genera. During the exploration of biodiversity of pleosporalean fungi in Taiwan, a fungal strain was isolated from mycelium growing on the fruiting body of an Ophiocordyceps species. Fruiting structures that developed on PDA were morphologically similar to Phoma and its relatives in having pycnidial conidiomata with hyaline conidia. The fungus is characterised by holoblastic, cylindrical, aseptate conidiogenous cells and cylindrical, hyaline, aseptate, guttulated, thin-walled conidia. Phylogenetic analysis based on six genes, ITS, LSU, rpb2, SSU, tef1 and tub2, produced a phylogenetic tree with the newly generated sequences grouping in a distinct clade separate from all of the known families. Therefore, a new pleosporalean family Tzeananiaceae is established to accommodate the monotypic genus Tzeanania and the species T.taiwanensis in Pleosporales, Dothideomycetes. The Ophiocordyceps species was identified as O.macroacicularis and this is a new record in Taiwan.

Keywords: Dothideomycetes; Pleosporineae; Entomopathogenic fungi; Multi-gene analysis; Phoma-like.

Figure 1.

Phylogenetic tree (RAxML) obtained from the DNA sequence data of ITS, LSU, rpb2, SSU, tef1 and tub2 sequences of 64 strains showing taxa in suborders Massarineae and Pleosporineae within Pleosporales. The new isolates are shown in bold, red. MP and ML bootstrap values (BS) ≥70% and Bayesian posterior probabilities (PP) ≥0.95 are presented at the nodes. Several branches were shortened to facilitate presentation of the tree and this is indicated by two diagonal lines with the number of times a branch was shortened. The scale bar shows the number of estimated mutations per site. The tree was rooted to Preussiaterricola (DAOM 230091).

Figure 2.

Phylogenetic tree (RAxML) obtained from the DNA sequence data of two loci (ITS and LSU) of Ophiocordycepsmacroacicularis and allied taxa. The new strain is shown in bold. MP and ML bootstrap values ≥70% and Bayesian posterior probabilities ≥0.95 are presented at the nodes and the scale bar shows the number of estimated mutations per site. The tree was rooted to Ophiocordycepssinensis (EFCC 7287).

Figure 3.

Morphology of Tzeananiataiwanensis (NTUCC 17-005) a Surface and lower view of colonies on PDAb Conidiomata sporulating on PDAc close-up of conidioma d close-up of Conidiomatal wall. e–f Conidiogenous cells g Conidia h Germinating conidia. Scale bars: 50µm (c), 10µm (d), 5µm (e–h).

Figure 4.

Morphology of Ophiocordycepsmacroacicularis (NTUH 17-004) a Close-up of ascomata b Close-up of the peridium c Hyaline, cylindrical, eight-spored ascus d Needle-shaped, multi-septate, hyaline ascospores. Scale bars: 20 μm (b), 50 μm (c–d).