Cyllamyces was the sixth anaerobic fungal genus to be described. Like Caecomyces, it is also a fungus that has a rhizomycelium with spherical holdfasts. Cyllamyces is considered to be distinctive from Caecomyces in terms of having a polycentric thallus, unlike Caecomyces which has a monocentric thallus. These bulbous fungi appear to have evolved a novel colonization mechanism involving use of hydrostatic pressure to disrupt feed particles.
Cyllamyces was formally classified by Ozkose et al in 2001, the name being derived from the Welsh word for ‘guts’ (Cylla). The type species is C. aberensis which was isolated from cattle faeces at the IBERS farm near Aberystwyth (hence aberensis). The type specimen is EO14 but sadly the associated ex-type culture is no longer viable. A second Cyllamyces species has also been described, C. icaris, which was isolated from an Indian water buffalo (Sridhar et al, 2014). C. icaris can be morphologically differentiated from C. aberensis in terms of having fewer sporangiophores that are larger in size.
Within the family Neocallimastigaceae, Cyllamyces is phylogenetically most closely related to Caecomyces and is close to Piromyces (based on LSU phylogeny). However, the placement of Cyllamyces within the broader bulbous clade is unclear and it is likely that the genus Caecomyces is paraphyletic (see Edwards et al, 2019 & references within).
Using ITS1 as a phylogenetic marker, the genetic distinctiveness of C. icaris from Caecomyces is not clear (Sridhar et al, 2014). However, further research is needed to resolve the relationship between the anaerobic fungal isolates currently classified as belonging to either of these genera. For example, some isolates may be incorrectly characterized as Cyllamyces or conversely Caecomyces.
Images are shown above of Cyllamyces cf. aberensis strains TSB2 (Image 1 & 2) and CFH681 (Images 3-6).
On solid roll agar media, it produces granular colonies (Image 1). It exhibits thin and loose biofilm-like growth in cellobiose liquid medium (Image 2). This macroscopic morphology is similar to Caecomyces.
Microscopically, Cyllamyces produces monoflagellated zoospores (Image 3). It has a characteristic polycentric thalli with a bulbous rhizoidal system and multiple sporangia (Images 4-6).
No sequenced genome or transcriptomes are currently available for Cyllamyces.
For Cyllamyces cf. aberensis strain TSB2 that is pictured above, the sequence information is available in the NCBI database (accession number MT085707: ITS1, 5.8S, ITS2 and D1/D2 LSU sequence data).