Fungalpedia – Note 462, Irineochytrium 

 

Irineochytrium Letcher, Longcore & M.J. Powell

Citation when using this data: Tibpromma et al. 2024 (in prep.) – Fungalpedia, Chytridiomycota.

Index Fungorum, Facesoffungi, MycoBank, GenBank, Fig. 1 

Classification: Chytridiaceae, Chytridiales, Chytridiomycetidae, Chytridiomycetes, Chytridiomycotina, Chytridiomycota, Fungi.

Based on DNA sequencing and ultrastructural analyses, Letcher et al. (2014) identified Irineochytrium as a monotypic genus within Chytridiaceae and Chytridiales in Chytridiomycetes with the type species I. annulatum. This species was initially described as Chytriomyces annulatus by Dogma (1970). Dogma (1970) placed Chytriomyces annulatus under Chytriomyces because it is epibiotic and operculate. Chytriomyces annulatus is widely reported worldwide (Dogma 1969, Booth & Barrett 1976, Letcher & Powell 2002) as a distinctive organism with a pyriform sporangium in which the sporangial wall is ornamented with multiple collar-like annulations typically proximal to the rhizoidal axis, a feature that has not been observed in any other chytrid (Letcher et al. 2014). No material appears to remain from Dogma’s collection of C. annulatus, and the new collections demonstrated the morphology and saprobic habitat of Dogma’s original description (Letcher et al. 2014). In phylogenetic analysis, C. annulatus does not group with the type of Chytriomyces, C. hyalinus, therefore, the new genus Irineochytrium was introduced to accommodate C. annulatus and named as I. annulatum (Letcher et al. 2014). In addition, Letcher et al. (2014) found zoospores and aplanospores are presented in Irineochytrium, the zoospore of I. annulatum has a unique suite of ultrastructural character states among Chytridiaceae zoospores. The occurrence of aplanospores in this isolate is an interesting feature. A few chytrids are considered aplanosporic (Hibbett et al. 2007). No other species have been introduced to this genus, which remains monotypic.

Type species: Irineochytrium annulatum (Dogma) Letcher, Longcore & M.J. Powell

Other accepted species: Species Fungorum – search Irineochytrium

 

Figure 1 – Morphology of Irineochytrium annulatum. a Developing thallus with pyriform sporangium (sporangium with collar-like annulations), rhizoidal axis, and branched rhizoids. b Immature epibiotic sporangium. c Release of nonmotile aplanospores. d Multiple aplanospores and a single flagellated zoospore. Scale bars: a = 5 μm, b = 20 μm, c, d = 10 μm. Redrawn from Letcher et al. (2014).

 

References 

Booth T, Barrett P. 1976 – Taxonomic and ecologic observations of zoosporic fungi in soils of a higharctic ecosystem. Canadian Journal of Botany 54, 533–538.

Dogma IJ. 1970 – Additions to the phycomycete flora of the Douglas Lake Region VIII. Chytriomyces annulatus sp. nov. and notes on other zoosporic fungi. Nova Hedwigia 18, 349–365.

Hibbett DS, Binder M, Bischoff JF, Blackwell M et al. 2007 – A higher-level phylogenetic classification of the Fungi. Mycological Research 111, 509–547.

Letcher PM, Powell MJ. 2002 – A taxonomic summary of Chytriomyces (Chytridiomycota). Mycotaxon 84, 447–487.

Letcher PM, Longcore JE, Powell MJ. 2014 – Irineochytrium, a new genus in Chytridiales having zoospores and aplanospores. Mycologia 106(6), 1188–1198.

 

Entry by

Lu L, Center for Yunnan Plateau Biological Resources Protection and Utilization, College of Biological Resource and Food Engineering, Qujing Normal University, Qujing, Yunnan 655011, China; Center of Excellence in Fungal Research, Mae Fah Luang University, Chiang Rai 57100, Thailand; School of Science, Mae Fah Luang University, Chiang Rai 57100, Thailand.

 

(Edited by Saowaluck Tibpromma, Samaneh Chaharmiri-Dokhaharani& Achala R. Rathnayaka)

 

Published online 3 December 2024

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