Kickxella alabastrina RSA 675 v1.0
Figure 1) White sporophores with a terminal whorl of fertile branches called sporocladia. Figures 2-4) At maturity, the fungus superficially resembles a compound flower produced by members of the Asteraceae, with umbellate sporocladia bearing densely packed, fusiform unispored sporangia on pseudophialides. Images by Kerry O'Donnell
Figure 1) White sporophores with a terminal whorl of fertile branches called sporocladia. Figures 2-4) At maturity, the fungus superficially resembles a compound flower produced by members of the Asteraceae, with umbellate sporocladia bearing densely packed, fusiform unispored sporangia on pseudophialides. Images by Kerry O'Donnell

Kickxella alabastrina Coemans RSA 675 = CBS 195.47 was collected originally by C.G. Dobbs on horse dung in Bangor, Wales United Kingdom in 1947.  It is the type species of the Order Kickxellales, which is classified within Phylum Zoopagomycota (Spatafora et al. 2016).  Members of this monotypic genus grow and sporulate asexually in pure culture at 15⁰C on the following medium: 4 g yeast extract, 4 g malt extract, 10 g peptone, 20 g agar per L.  As the epithet suggests, this iconic species produces white sporophores with a terminal whorl of fertile branches called sporocladia (Fig. 1).  At maturity, the fungus superficially resembles a compound flower produced by members of the Asteraceae, with umbellate sporocladia bearing densely packed, fusiform unispored sporangia on pseudophialides (Figs. 2-4).  Sporangia are passively released into a droplet where they are likely dispersed via a rain splash dispersal mechanism.  The available molecular phylogenetic data suggests that Kickxella + Linderina (O’Donnell et al. 1998) or Kickxella + Coemansia (Tretter et al. 2014) are sisters.  The sexual cycle involves fusion of undifferentiated hyphae followed by production of a smooth, thin walled zygospore, when cultured at 7⁰C (Benjamin 1958).  The whole-genome sequence of K. alabastrina will be useful in resolving its evolutionary relationships and in increasing our understanding of the phylogeny of the early diverging fungi as part of the NSF-funded Zygomycetes Genealogy of Life project (http://zygolife.org/home/) and JGI’s Early Diverging Fungi – 1KFG Community Sequencing Project (http://1000.fungalgenomes.org/home/).

References:

Benjamin RK. 1958. Sexuality in the Kickxellaceae. Aliso 4:149─169.

O’Donnell K, Cigelnik E, Benny GL. 1998. Phylogenetic relationships among the Harpellales and Kickxellales. Mycologia 90:624─639.

Spatafora JW, Chang Y, Benny GL, Lazarus K, Smith ME, Berbee ML, Bonito G, Corradi N, Grigoriev I, Gryganskyi A, James TY, O’Donnell K, Roberson RW, Taylor TN, Uehling J, Vilgalys R, White MM, Stajich JE. 2016. A phylum-level phylogenetic classification of zygomycete fungi based on genome-scale data. Mycologia 108:1028─1046.

Tretter ED, Johnson EM, Benny GL, Lichtwardt RW, Wang Y, Kandel P, Novak SJ, Smith JF, White MM. 2014. An eight-gene molecular phylogeny of the Kickxellomycotina, including the first phylogenetic placement of Asellariales. Mycologia 106:912─935.