Zoopagomycotina

The Zoopagomycotina are a subdivision ("incertae sedis") of the fungal division Zygomycota "sensu lato". It contains 5 families and 20 genera. Relationships among and within subphyla of Zygomycota are poorly understood, and their monophyly remains in question, so they are sometimes referred to by the informal name zygomycetes.
Zoopagomycotina are microscopic and are typically obligate parasites of other zygomycete fungi and of microscopic soil animals such as nematodes, rotifers and amoebae.<ref name="[tolweb.org/Zygomycota]"> url=http://www.tolweb.org/Zygomycota</ref> Some species are endoparasites that live mostly within the bodies of their hosts and only exit the host when they are producing spores. Other species are ectoparasites (e.g. "Syncephalis", "Piptocephalis") that live outside of the host body but produce specialized organs called haustoria that penetrate inside of the host body to capture host nutrients. Similar haustoria are found in biotrophic plant, animal and fungal pathogens in several other major fungal lineages.
Like most other zygomycete fungi, the Zoopagomycotina have cell walls containing chitin and have coenocytic (nonseptate) hyphae. Their vegetative body consists of a simple, branched or unbranched thallus. Asexual reproduction is by arthrospores (in "Helicocephalum"), chlamydospores, uni- or multi-spored sporganiola; sporangiospores of multi-spored formed in simple or branched chains (merosporangia), usually from a vesicle or stalk. Many produce haustoria. Where observed, the sexual spores (zygospores) are globose and unornamented. The hyphae used during sexual outcrossing is similar to vegetative hyphae or in some cases may be slightly enlarged.
Etymology.
The word Zoopagomycotina comes from the Greek roots "zoo" meaning "animal" and "pag" meaning "rock" or "ice/frost".
Evolutionary relationships.
Although great strides have been made in resolving the evolutionary relationships among many lineages of fungi, it has been challenging to resolve relationships within and among zygomycetes. For example, the uncertain grouping of "Zoophagus insidians" with the Kickxellomycotina.
Resolving a well-supported monophyly of the Zoopagomycotina has been particularly challenging for several main reasons: