Fungalpedia – Note 96 Hypomyces
Hypomyces (Fr.) Tul. & C. Tul.
Citation when using this entry: Gajanayake et al., in prep – Fungalpedia, fungicolous fungi. Mycosphere.
Hypomyces (Hypocreaceae, Hypocreales) was originally considered as a subgenus of Hypocrea Fr. by Fries (1825), but later it was raised to genus rank by Tulasne & Tulasne (1860). Hypomyces lactifluorum (Schwein.) Tul. & C. Tul. which was originally discovered on Agaricus lactifluus, collected from the USA, was designated as the type species of Hypomyces. Arnold (1971) conducted the first comprehensive taxonomic study for Hypomyces and differentiated it from the closely related Arachnocrea, Apiocrea, and Peckiella. Thereafter, several studies on Hypomyces were conducted (Rogerson & Samuels 1985, 1989, 1993, 1994; Põldmaa 1996, 2003, 2011; Põldmaa et al. 1997, 2000). Accordingly, a link between asexual morphs of Hypomyces and Cladobotryum was revealed based on morphology and phylogeny (Rogerson & Samuels 1993, 1994; Poldmaa 2003, 2011). The use of Hypomyces over Cladobotyrum was recommended (Rossman et al. 2013; Hyde et al. 2020).
Hypomyces are fungicolous taxa associated with Ascomycota and Basidiomycota, but some taxa (H. mycophilus, H. perniciosus) are pathogenic on commercially cultivated mushrooms (Rogerson & Samuels 1993, 1994; Põldmaa et al. 2000; Põldmaa 2003; Gea et al. 2021; Zhang et al. 2023). Occasionally, Hypomyces taxa have been reported in association with plant and other substrates such as bark, wood, leaves, mosses, humus, rocks, insect galls and lichens (Rogerson & Samuels 1993, 1994; Lechat et al. 2017; Farr et al. 2021; Karimi et al. 2022; Perera et al. 2023). Hypomyces has a cosmopolitan distribution with most taxa reported as pathogens or saprobes (Rogerson & Samuels 1993, 1994; Rossman et al. 1999; Põldmaa 1996, 2003, 2011). Bioactive metabolites of Hypomyces chrysospermus are an important resource for the pharmaceutical and drug industries. Hypomyces chrysospermus has anticancer, antimicrobial, and antioxidant properties including anti-metastatic and anti-proliferative activity (Chakraborty et al. 2016; Dikmen et al. 2020).
The sexual morph of Hypomyces is characterized by peritheical ascomata which are superficial on or semi immersed to immersed in a concolorous subiculum. Asci are cylindrical and 8-spored. Ascospores are partially overlapping, uniseriate, fusiform with blunt or acute ends, spinulose to tuberculate or verrucose and hyaline (Rossman et al. 1999; Poldmaa 2011; Perera et al. 2023). The asexual morph of Hypomyces is hyphomycetous and it is characterized by conidiophores that are usually micronematous, occasionally semi-macronematous to macronematous, aseptate or septate and form verticils on the conidiogenous cells. Conidiogenous cells produce one to several conidiogenous loci. Conidia are solitary, usually ellipsoidal to fusiform, cylindrical, ovoid, obovoid or clavate and hyaline to green (Rossman et al. 1999; Poldmaa 2011, Perera et al. 2023).
The current identification of Hypomyces taxa is based on morphological characteristics combined with multigene phylogenetic analyses. The recommended molecular markers for Hypomyces species are ITS, LSU, rpb1, rpb2 and tef 1-α (Rehner & Samuels 1995; Põldmaa 2000; Põldmaa et al. 2000; Põldmaa 2011; Zare & Gams 2016). To date, 118 Hypomyces taxa are listed in Species Fungorum (2023) and around 60 taxa have molecular data.
Type species: Hypomyces lactifluorum (Schwein.) Tul. & C. Tul.
Other accepted species: See Species Fungorum – search Hypomyces for names.
Figure 1 – Hypomyces lactifluorum (PH00076754) a Host (Lactarius sp.). b Ascomata on host. c, d Vertical section of ascomata. e Hyphae of the subiculum in 3% KOH. f Section of peridium in 3% KOH. g Ascus. h Illustration of ascal apex (Redrawn from Rogerson & Samuels 1994). i–n Ascospores. Scale bars: b, c, d = 200 μm, g = 80 μm, e = 50 μm, f, h–n = 20 μm. Photo Credits: R.H. Perera.
Arnold GRW. 1971 – Zur Systematik der Hypomycetaceae. Nova Hedwigia 21, 529–535.
Dikmen M, Ozturk SE, Canturk Z, Ceylan G et al. 2020 – Anticancer and antimetastatic activity of Hypomyces chrysospermus, a cosmopolitan parasite in different human cancer cells. Mol Biol Rep 47, 3765–37678
Fries E. 1825 – Systema orbis vegetabilis: Primas lineas novae constructionis periclitatur Elias Fries. e Typographia Academica.
Perera RH, Hyde KD, Jones EBG, Maharachchikumbura SSN et al. 2023 – Profile of Bionectriaceae, Calcarisporiaceae, Hypocreaceae, Nectriaceae, Tilachlidiaceae, Ijuhyaceae fam. nov., Stromatonectriaceae fam. nov. and Xanthonectriaceae fam. nov. Fungal Diversity 118, 95–271.
Põldmaa K, Larsson E, Kõljalg U. 2000 – Phylogenetic relationships in Hypomyces and allied genera, with emphasis on species growing on wood-decaying homobasidiomycetes. Canadian Journal of Botany 77, 1756–1768.
Gajanayake A.J, Center of Excellence in Fungal Research, Mae Fah Luang University, Chiang Rai, Thailand and School of Science, Mae Fah Luang University, Chiang Rai 57100, Thailand.
(Edited by Ruvishika S. Jayawardena & Kevin D. Hyde)