Chlamydoabsidia padenii Hesselt. & J. J. Ellis 1966

Chlamydoabsidia(Hesseltine and Ellis, 1966) resemblesAbsidiabecause it forms multispored sporangia with a prominent columella and a deliquescent wall. A single septum is produced in the sporangiophore subtending the sporangium. Large, pigmented, more or less fusiform, multiseptate chlamydospores are formed in the aerial mycelium. Zygospores are unknown. (Zygomycetes.org 2015)

Species ofChlamydoabsidia:
C. padeniiHesseltine & Ellis, 1966 (Mycologia 58:763).

This genus was described (Hesseltine and Ellis, 1966) based onC. padenii.Chlamydoabsidia padeniiwas transferred toAbsidiaby Mil’ko (1968, 1970) and Váňová (1980). The second species,C. dasguptii(Behera and Mukerji, 1974), is considered a synonym ofC. padeniiaccording to theIndex of Fungionline (http://www.indexfungorum.org/). (Zygomycetes.org 2015)

Taxonomy and Phylogeny

Chlamydoabsidia padenii was first isolated at the University of Idaho from pea roots by John Paden in 1960 and was described by Hesseltine and Ellis. According to Index of Fungi (http://www.indexfungormum.org/) the one synonym to C. padenii is C. dasguptii, which was described by Behera and Mukerji in 1974. Through experiments testing mating compatibility, C. padenii had very strong mating fusions with members of the genus Absidia, specifically with the species Absidia coerulea and Absidia repens exhibiting that C. padenii is very closely related to the globose-spored as well as the oval spored species of Absidia and that it possesses a (+) mating reaction (Hesseltine & Ellis, 1966). Molecular phylogenetic studies have confirmed C. padenii as an individual species that shares a recent common ancestor with the sister species Absidia repens, confirming the original placement of C. padenii in the family Mucoraceae (Benny et. al., 2001). It belongs to the order Mucorales and to the class Absidia.

Morphology

When cultured on a medium of synthetic Mucor agar (SMA) the fungus can appear to be floccose, growing to the lid of a Petri dish, almost completely filling a Petri dish in 12 days at 25 C” (Hesseltine & Ellis, 1966). The mycelium can have a changing color appearance as it ages ranging from a light brown to almost an olive gray when young to a darker cinnamon after roughly 30 days of growth in culture. The mycelium will appear “rather tan, with irregular radiating folds from the point of inoculation, the substrate mycelium growing outward and encircled by secondary colonies, and at the edge of the dish showing only the color of the aerial mycelium through the agar” (Hesseltine & Ellis, 1966). The smell of this fungus is unpleasant, often described as “penetrating and musty” (Hesseltine & Ellis, 1966). The vegetative mycelium lacks oidia, “chlamydospores or giant cells” (Hesseltine & Ellis, 1966). However this species will take on somewhat different morphological characteristics when grown on different media types. This species was best described on Czapek’s solution agar (CSA) “since sporangia are not formed on SMA” (Hesseltine & Ellis) in order to provide a full morphological description of the cultured Chlamydoabsidia padenii. The following description is based on the mycelial growth on CSA. This media type, being less nutrient dense, allows for the production of sporangiophores “155-570 X 3 – 9 μ, erect, arising singly from stolons and also directly from the substrate mycelium, hyaline, minutely striate and sometimes encrusted with crystals, nonseptate except for a septum always under the sporangium, usually simple but sometimes sympodially branched to two or three times with each successive sporangium borne above the last” (Hesseltine & Ellis, 1966). Growth on this substrate allows for the production of stolons ranging from “4.5 – 21.5 μ in diam” and appearance described as “granular or very faintly roughened or punctuate under oil immersion” (Hesseltine & Ellis, 1966). Stolons generally only have a single septation and a glassy appearance, becoming more darkly pigmented brown near the chlamydospores (Hesseltine & Ellis, 1966). Rhizoids tend to take the same light glassy appearance as the mycelium and can grow up to 6.5 μ in diameter, slightly branched and twisted becoming tapered near the end. They will generally lack a septum but in some cases will possess one (Hesseltine & Ellis, 1966). The sporangia will tend to be pale yellow in color and pear shaped, “12-35(-40) μ” in size, and are “many-spored, borne erect” (Hesseltine & Ellis, 1966). The sporangial wall tends to absorb liquid from the air and dissolve in it giving it a transparent look (Hesseltine & Ellis, 1966). The columellae are typically ovular, with a collar, ranging from 6.5 – 25 μ in diameter, with a similar smooth glassy sheen, like the mycelium, with a single terminal projection. This projection is as long as 4.5 μ (Hesseltine & Ellis, 1966). Sporangiospores will be smooth, colorless, and globose, with a diameter of 3.5-5.5 (-6.6) μ; zygospores are not seen in this species; sexual mating is heterothallic (Hesseltine & Ellis, 1966). One of the distuinguishing characters of this species is its production of chlamydospores. The chlamydospores can range from 26 – 78 μ in diameter, are present at the terminal end of aerial mycelium opposite the rhizoids, are “often covered with droplets of exudate”, are often elliptically shaped but sometimes irregular,and have “a papilla at the distal end” (Hesseltine & Ellis, 1966). The chlamydospores will be thick-walled and separated from the mycelium by a single septation. The spore wall is dark brown to black in color and is filled with dense cytoplasm (Hesseltine & Ellis, 1966).

Ecology

This species will produce different structures when grown under different conditions, specifically the media type and nutrient density. A thick vegetative mycelium will be produced when grown on nutrient rich media, in contrast to the production of reproductive structures and thin, anemic mycelium when grown on nutrient poor media (Hesseltine & Ellis, 1966).

Overall Biology and Relevance for Humans

This species contributes to evolutionary genetic work being done to understand the loss of a flagellum, since zoopagomycetes are the earliest group to have lost their flagella.

Other External Links for C. padenii

Mycobank

Zygomycetes

Index Fungorum

Chlamydoabsidia padenii je grzib, co go ôpisoł Hesselt. & J.J. Ellis 1966. Chlamydoabsidia padenii nŏleży do zorty Chlamydoabsidia i familije Cunninghamellaceae. Żŏdne podgatōnki niy sōm wymianowane we Catalogue of Life.