Fungalpedia – Note 3298, Trigonopsidomycetes
Trigonopsidomycetes M. Groenew., Hittinger, Opulente & A. Rokas Stud. Mycol. 105: 16 (2023).
Citation when using this data: Wijayawardene NN et al. 2024 – Fungalpedia.
Index Fungorum, Faceoffungi, MycoBank, GenBank, Fig 1v.
Classification: Saccharomycotina, Ascomycota, Dikarya, Fungi.
Notes: The class Trigonopsidomycetes in the subphylum Saccharomycotina was introduced by Groenewald et al. (2023), who, based on the analysis of genomic data, proposed the distribution of the yeasts assigned to Saccharomycotina among seven classes. They provided a diagnosis of Trigonopsidomycetes with class-specific orthologous groups of proteins (OGs) (for more details see the entry Saccharomycetes). Members of the Trigonopsidales form a mildly supported monophyletic clade as per LSU, MtSm and COXII sequence analyses (Kurtzman and Robnett 2007; Kurtzman and Robnett 2013b; Lachance and Kurtzman 2013) and the phylogenomic analyses done by Shen et al. (2018). Groenewald et al. (2023) is the latest study that provides a comprehensive background on the taxonomy of the higher-level classification of Trigonopsidales. Phylogenetic analysis of D1/D2 LSU rRNA gene sequences demonstrated that the two described species of Botryozyma are quite closely related to one another as well as to the two known species of Ascobotryozyma (Kerrigan and Smith 2011), and thus represent a single genus in the new single nomenclature system. The Melbourne Code assigns equal weight to anamorphic and teleomorphic genus names. Because the genus Botryozyma (1992) has priority of date over Ascobotryozyma (2001), Lachance and Kurtzman (2013) propose assigning the species of this clade to the genus Botryozyma. Considering the exceptional early divergence of the basal branching point marking this order, additional data may eventually support the division of this new order. However, due to the lack of additional species, Groenewald et al. (2023) have decided to combine the genera Trigonopsis, Tortispora, and Botryozyma into one order, while acknowledging that future descriptions of more species in this group may lead to the split of Tortispora and Botryozyma from Trigonopsis into a separate class.
The economic and ecological significance of members of this class is unknown, as is whether they have any application in the medical/clinical field. However, the ability of Trigonopsis variabilis to produce D-amino acid oxidases that catalyse the oxidative deamination of α-amino acids to α-keto acids and ammonia (Kurtzman 2011) is of great importance to the pharmaceutical industry. Other uses for this enzyme include the synthesis of chiral intermediates to produce antihypertensive drugs (Patel 2001) and the conversion of cephalosporin C to 7-amino cephalosporanic acid, which is a key intermediate for cephem antibiotics (Dib and Nidetzky 2008).
According to Groenewald et al. (2023), currently, the class comprises one order Trigonopsidales, one family Trigonopsidaceae and three genera (Botryozyma, Tortispora and Trigonopsis).
Type order: Trigonopsidales M. Groenew., Hittinger, Opulente & A. Rokas. Stud. Mycol. 105: 16 (2023).
Type family: Trigonopsidaceae Lachance & Kurtzman, Int. J. Syst. Evol. Microbiol. 63: 3113 (2013).
Type genus: Trigonopsis Schachner, Z. Ges. Brauwesen 52: 137 (1929).
Type species: Trigonopsis variabilis Schachner, Z. Ges. Brauwesen 52: 137 (1929).
Other accepted species: Species Fungorum – search Trigonopsidomycetes.
Figure 1 – Microscopic features of taxa in Saccharomycotina. a Septate non-sporulating hyphae and pseudohyphae of Alloascoidea hylecoeti (Alloascoideaceae, Alloascoideales, Alloascoideomycetes). b-d Alloascoidea africana (Alloascoideaceae, Alloascoideales, Alloascoideomycetes) asci with ascospores and released ascospores (indicated with arrows). e,f Dipodascus albidus (Dipodascaceae, Dipodascales, Dipodascomycetes). e. Ascospores within hyphae and released ascospores. f Hyphae, arthroconidia and ascospores (indicated by arrow). g Lipomyces starkeyi (Lipomycetaceae, Lipomycetales, Lipomycetes) conjugation between a cell and its bud, ascus with ellipsoidal ascospores (indicated by arrows). h-j Pichia membranifaciens (Pichiaceae, Pichiales, Pichiomycetes) budding cells and asci with hat-shaped ascospores (indicated by arrows). k Pachysolen tannophilus (Pachysolenaceae, Alaninales, Pichiomycetes) budding cells, ascus with ascospores and liberated ascospores (indicated by arrow). l,m Metschnikowia bicuspidata (Metschnikowiaceae, Serinales, Pichiomycetes). (l) M. bucuspidata var. californica budding cells and needle-shaped ascospores. (m) M. bucuspidata var. chathamia budding cells and needle-shaped ascospores. n Saccharomyces cerevisiae (Saccharomycetaceae, Saccharomycetales, Saccharomycetes) budding cells and unconjugated, persistent ascus with globose ascospores (indicated by arrow). o, p Phaffomyces opuntiae (Phaffomycetaceae, Phaffomycetales, Saccharomycetes). (o) Budding cells and asci with hat-shaped ascospores (indicated by arrows). (p) Budding cells in short chains and asci with hat-shaped ascospores (indicated by arrows). q Saccharomycodes ludwigii (Saccharomycodaceae, Saccharomycodales, Saccharomycetes) bipolar cell division of budding cells and asci with spherical ascospores (indicated by arrows). r-t Ascoidea rubescens (Ascoideaceae, Ascoideales, Saccharomycetes). (r) Asexual cells and cluster of ascospores (indicated by arrow) (s) Asexual cells and septate hyphae, (t) Ascus with spores in different states of nascendi. u Sporopachydermia lactativora (Sporopachydermiaceae, Sporopachydermiales, Sporopachydermiomycetes) budding cells. v Trigonopsis variabilis (Trigonopsidaceae, Trigonopsidales, Trigonopsidomycetes). Budding cells with ellipsoidal and triangular morphology. Triangular cells produce ellipsoidal and triangular buds. Scale bar: a = 5μm, b-q, u,v = 10μm, r-t =30μm.
References
Entry by
Nalin N. Wijayawardene, Center for Yunnan Plateau Biological Resources Protection and Utilization, College of Biological Resource and Food Engineering, Qujing Normal University, Qujing, Yunnan 655011, P.R. China, Tropical Microbiology Research Foundation, 96/N/10, Meemanagoda Road, 10230 Pannipitiya, Sri Lanka, Department of Bioprocess Technology, Faculty of Technology, Rajarata University, Sri Lanka
Published online 25 September 2026