Not much is known about U. dimorpha and its relevance for humans. Interestingly, U. ramanniana, a close relative, has been shown to contain a gene involved in oil production that has relevance for soybean oil production. Transgenic expression of this gene in soybean resulted in a high-oil producing soybean line (Lardizabal et al. 2008). As a close relative to U. dimorpha, the production of long chain fatty acids in U. dimorpha may hold promise.
Not much is known about the specific ecology of this species, however many species within the genus, Umbelopsis, are regarded as saprotrophs. It was originally isolated in an area where the dominant plant species were Kunzea ericoides, a shrub only found in New Zealand and Austrailia, and the grasses Poa acneps, Festuca novaezelandiae, and Rytidosperma gracile (Mahoney eta al. 2004). It is not known if U. dimorpha forms any symbiotic relationships with plants, however the closely related, non-mycorrhizal, U. nana has been shown to improve the mycorrhizal interaction between Cymbidium hybridum (an orchid species) and Epulohiza repens (Zhao et al. 2014b,2014a). The study examining the community structure of prescribed fire sites in Georgia mentioned that treatments with burns every 2 and 3 years had OTU belonging to a member of Umbelopsis (Oliver et al. 2015). Since zygospores are not readily formed in culture, it is uncertain if they form in nature, and is assumed that U. dimorpha is asexual and haploid. Even though not much is known about the specific ecology of U. dimorpha, interesting ecological phenomenon have been discovered in other members of Umbelopsis.
Umbelopsis dimorpha has only been isolated from soils. It was first isolated in New Zealand from greywacke soils (Mahoney et al. 2004). These soils are characterized by having coarse grains with > 15% clay. It was also isolated from broad leaved forest soil from various regions of China (Wang et al. 2013). Currently, China and New Zealand are the only confirmed reported geographic regions, however the geographic distribution is likely larger. For example, a study examining the fungal community structure of prescribed fire sites in Georgia, USA, showed that one of the most abundant operational taxonomic unit (OTU) present among soil dwelling fungi had similarity to U. dimorpha (Oliver et al. 2015).
Mahoney et al. (2004) describes the genus Umbelopsis as containing species with pigmented aseptate spores with the sporangiophore close to the sporangium, and species with large spores arising from hyaline deciduous sporangia. Zygospores have currently not been observed (Wang et al. 2013). Hyphae are hyaline and about 5-8 μm diameter. Colonies usually appear reddish pink with white sectoring (Wang et al. 2013). The color of the colonies are due to the sporangia. U. dimorpha gets its name from the Greek prefix –di, meaning two, and the plural form of the Latin suffix, –morphus, meaning shape, or form, indicating that U. dimorpha shows characteristics of both morphology types present in Umbelopsis under different growth conditions. One morphotype is similar to the single spored U. nana, whereas the second is more simmilar to U. versiformis, the multispored sister taxa (Mahoney et al. 2004).
Single spored morphology. Colonies of U. dimorpha on corn meal agar (CMA) and potato carrot agar (PCA) have short hyaline sporangiophors (12.5 to 75 μm long) containing a single sporangiospore inside the sporangium and without a collumella. Sporangiospores arising from single spored sporangium are hyaline, smooth and globose (6-10 μm).
Multi-spored morphology. Colonies of U. dimorpha on potato dextrose agar (PDA) and malt extract agar (MEA) contain multi-spored sporangia which form a pink to reddish hue from the color of the sometimes long (>300 μm) sporangiophores. Sporangia are smooth, globose and columellate. Columella swell 4-5 μm above the sporangiophore. Columella do not have a collar or septa beneath. Sporangiospores are typically hyaline to reddish and angular (2.5 to 5 μm diameter). Occasionally chlamydospores (≤ 10 μm diameter) and hyphal swellings occur that are smooth, hyaline and subglobose (Mahoney et al. 2004). The maximum growth temperature for U. dimorpha is 39ºC (Wang et al. 2013).
Umbelopsis dimorpha (Mahoney et al. 2004) was first described in 2004 from the “Red Hills area of Mt Richmond Forest Park, in the northern part of the South Island of New Zealand” (Mahoney et al. 2004). Umbelopsis nana and Umbelopsis versiformis are its closest relatives in the Umbelopsis genus. Umbelopsis is an early diverging lineage of phylum Mucoromycota (formerly Zygomycota) in the subphylum Mucoromycotina (Spatafora et al. 2016). Umbelopsis dimorpha belongs to the order Umbelopsidales and family Umbelopsidaceae (Spatafora et al. 2016).
Mahoney and Gams noted Umbelopsis dimorpha has similar ITS-1 sequences and morphology as U. nana to U. versiformis and was therefore placed onto a phylogeny with these two sister species (Mahoney et al. 2004). The Umbelopsis phylogeny is not complete, but using multiple genes and modern phylogenetic techniques, places U. dimorpha as a basal lineage to the Umbelopsidaceae. Walther et. al. suggested that U. nana and U. dimorpha may be conspecific (Walther et al. 2013), however Wang et. al. recommended keeping U. dimorpha as a separate species (Wang et al. 2015) (Figure 1). A new phylogeny, based on 192 orthologous proteins, placed Umbelopsis ramanniana (a closely related species) as the basal lineage to the Mucoromycotina subphylum (Spatafora et al. 2016). Since the Umbelopsis is a basal lineage to mucoromycotina and U. dimorpha is a basal lineage to Umbelopsidaceae, it could be hypothesized that U. dimorpha is the most basal member of the subphylum Mucoromycotina, making it an important transition species between Mortierellomycotina and Mucoromycotina subphyla. However, molecular evidence to support this hypothesis needs to be collected.
