Belongs within: Pucciniomycetes.
Rust waits for no spring
It should not come as a surprise to anyone that rust fungi have a complicated taxonomic history. The complexities of their nightmarish life cycles are something I’ve considered elsewhere; go there if you feel the need for a refresher. There are many rust species for which the life cycles have not yet been clarified, with available descriptions based on a single life stage. Conversely, rusts show the usual tendency of parasitic organisms towards morphological simplification, meaning that those features that can be observed are often fairly broad and open to convergence. An example of both issues can be presented in the case of Chaconiaceae.
The chaconioid rusts were first recognised as a tribe of the family Pucciniaceae back in 1928, at a time when rusts were divided between only two families (Ono & Hennen 1983). In the usual way of these things, later authors recognised more families as research progressed, and the Chaconiaceae were awarded the status of a distinct family in 1983. Kirk et al. (2001) assigned ten genera to the Chaconiaceae. These were mostly found in tropical regions, with many being poorly studied as a result. Nevertheless, Chaconiaceae were united by the production of unicellular teliospores that germinated without going through a dormancy stage.
Because of the simplicity of their spore morphology, some authors speculated whether Chaconiaceae might represent a primitive lineage within the rust fungi. However, the advent of molecular data brought quite a different picture. The chaconioid rusts have proven to be polyphyletic, divided between multiple widely separated lineages (Aime & McTaggart 2020). As a result, ‘Chaconiaceae’ has been abandoned as a distinct family. The chaconioid spores are not a primitive feature but a convergent development, probably as an adaptation to tropical climes. When you grow in a location that does not exhibit strong seasonal variation, there is simply no need to prepare yourself for dormancy.
Systematics of Chaconiaceae
ChaconiaceaeKC01
|--Achrotelium Syd. 1928KC01
|--Aplopsora Mains 1921KC01
|--Botryorhiza Whetzel & Olive 1917KC01
|--Ceraceopsora Kakish., Sato & Sato 1984KC01
|--Ceropsora Bakshi & Singh 1960KC01
|--Chrysocelis Lagerh. & Dietel 1913KC01
|--Goplana Racib. 1900KC01
|--Maravalia Arthur 1922 (see below for synonymy)KC01
|--Olivea Arthur 1917 [incl. Tegillum Mains 1940]KC01
`--Chaconia Juel 1897 [incl. Bitzea Mains 1939, Desmotelium Syd. 1937]KC01
`--C. ingae (Sydow) Cummins 1956 (see below for synonymy)HH03
Chaconia ingae (Sydow) Cummins 1956 [=Maravalia ingae Sydow 1925, Bitzea ingae (Sydow) Mains 1939; incl. Uredo excipulata Sydow & Sydow 1904, Uredo ingae Lagerheim in Arthur 1917 (n. n.) non Henn. 1899, Uromyces ingaeiphilus Spegazzini 1925, Uro. ingicola Henn. 1904, Uredo mogy-mirim Viégas 1945, Uro. porcensis Mayor 1913, Maravalia urticulata Sydow 1925, Ravenelia whetzelii Arthur 1917]HH03
Maravalia Arthur 1922 [incl. Acervulospora Thirum. 1945, Angusia Laundon 1964, Argomycetella Syd. 1922, Scopella Mains 1939, Scopellopsis Ramakr. & Ramakr. 1947]KC01
*Type species of generic name indicated
References
Aime, M. C., & A. R. McTaggart. 2020. A higher-rank classification for rust fungi, with notes on genera. Fungal Systematics and Evolution 7: 21–47.
[HH03] Hernández, J. R., & J. F. Hennen. 2003. Rust fungi causing galls, witches’ brooms, and other abnormal plant growths in northwestern Argentina. Mycologia 95 (4): 728–755.
[KC01] Kirk, P. M., P. F. Cannon, J. C. David & J. A. Stalpers. 2001. Ainsworth & Bisby’s Dictionary of the Fungi 9th ed. CAB International: Wallingford (UK).
Ono, Y., & J. F. Hennen. 1983. Taxonomy of the chaconiaceous genera (Uredinales). Trans. Mycol. Soc. Japan 24: 369–402.