Amoebidiidae is a

family Family (from la, familia) is a group of people related either by consanguinity (by recognized birth) or affinity (by marriage or other relationship). The purpose of the family is to maintain the well-being of its members and of society. Idea ...

of single-celled eukaryotes, previously thought to be

zygomycete Zygomycota, or zygote fungi, is a former phylum, division or phylum of the kingdom Fungi. The members are now part of two Phylum, phyla: the Mucoromycota and Zoopagomycotina, Zoopagomycota. Approximately 1060 species are known. They are mostly t ...

fungi A fungus ( : fungi or funguses) is any member of the group of eukaryotic organisms that includes microorganisms such as yeasts and molds, as well as the more familiar mushrooms. These organisms are classified as a kingdom, separately from ...

belonging to the clas
Trichomycetes
but molecular phylogenetic analysesBenny, G. L., and O'Donnell, K. 2000. ''Amoebidium parasiticum'' is a protozoan, not a Trichomycete. ''Mycologia'' 92: 1133-1137.Ustinova, I, Krienitz, L., and Huss, V. A. R. 2000. ''Hyaloraphidium curvatum'' is not a green alga, but a lower fungus; ''Amoebidium parasiticum'' is not a fungus, but a member of the DRIPS. ''Protist'' 151: 253-262.Cafaro, M. 2005. Eccrinales (Trichomycetes) are not fungi, but a clade of protists at the early divergence of animals and fungi. Molecular Phylogenetics and Evolution 35: 21-34. place the family with the

opisthokont The opisthokonts () are a broad group of eukaryotes, including both the animal and fungus kingdoms. The opisthokonts, previously called the "Fungi/Metazoa group", are generally recognized as a clade. Opisthokonts together with Apusomonadida and ...

group

Mesomycetozoea The Mesomycetozoea (or DRIP clade, or Ichthyosporea) are a small group of Opisthokonta in Eukaryota (formerly protists), mostly parasites of fish and other animals. Significance They are not particularly distinctive morphologically, appearing in ...

Mendoza L, Taylor JW, Ajello L (October 2002)
"The class mesomycetozoea: a heterogeneous group of microorganisms at the animal-fungal boundary"
''Annu. Rev. Microbiol''. 56: 315–44. doi: 10.1146/annurev.micro.56.012302.160950 (= Ichthyosporea). The family was originally called Amoebidiaceae, and considered the sole family of the fungal order Amoebidiales that included two genera: '' Amoebidium'' and '' Paramoebidium''. However, Amoebidiidae is now monogeneric as it was recently emended to include only ''Amoebidium'' (and ''Paramoebidium'' is now the sole genus of the family Paramoebidiidae).Reynolds, N.K., M.E. Smith, E.D. Tretter, J. Gause, D. Heeney, M.J. Cafaro, J.F. Smith, S.J. Novak, W.A. Bourland, M.M. White. 2017. Resolving relationships at the animal-fungal divergence: A molecular phylogenetic study of the protist trichomycetes (Ichthyosporea, Eccrinida). Molecular Phylogenetics and Evolution in press, available online 20Feb.2017. https://dx.doi.org/10.1016/j.ympev.2017.02.007 Species of ''Amoebidium'' are considered obligate symbionts of freshwater-dwelling arthropod hosts such as midge larvae and water fleas (''

Daphnia ''Daphnia'' is a genus of small planktonic crustaceans, in length. ''Daphnia'' are members of the order Anomopoda, and are one of the several small aquatic crustaceans commonly called water fleas because their saltatory swimming style resembl ...

'').Lichtwardt, R.W. 2001. Trichomycetes: fungi in relationship with insects and other arthropods. In: ''Symbiosis''. J. Seckbach, ed. Kluwer Academic Publishers, Netherlands, p. 515-588. However, because ''Amoebidium'' species attach to the

exoskeleton An exoskeleton (from Greek ''éxō'' "outer" and ''skeletós'' "skeleton") is an external skeleton that supports and protects an animal's body, in contrast to an internal skeleton (endoskeleton) in for example, a human. In usage, some of the ...

(exterior) of the host and grow in axenic culture, at least some species may be facultative symbionts.Lichtwardt, R.W., M.J. Cafaro, M.M. White. 2001. The Trichomycetes: Fungal Associates of Arthropods Revised Edition. Published online http://www.nhm.ku.edu/%7Efungi/Monograph/Text/Mono.htm

Etymology

The "amoeb-" prefix refers to the

amoeba An amoeba (; less commonly spelled ameba or amœba; plural ''am(o)ebas'' or ''am(o)ebae'' ), often called an amoeboid, is a type of cell or unicellular organism with the ability to alter its shape, primarily by extending and retracting pseudop ...

-like dispersal cells that are produced during the life cycle of ''Amoebidium''.Lichtenstein, J. L. 1917a. Sur un ''Amoebidium'' a commensalisme interne du rectum des larves dAnax'' ''imperator'' Leach: ''Amoebidium'' ''fasciculatum'' n. sp. ''Archives de Zoologie Expérimentale et Générale'' 56: 49-62.

Description

As the family is monogeneric, the description follows that of the genus, ''Amoebidium''. ''Amoebidium'' species are single-celled, cigar-shaped or tubular in vegetative growth form (=

thallus Thallus (plural: thalli), from Latinized Greek (), meaning "a green shoot" or "twig", is the vegetative tissue of some organisms in diverse groups such as algae, fungi, some liverworts, lichens, and the Myxogastria. Many of these organisms ...

), and attach to the exoskeleton of various freshwater arthropod hosts ( Crustaecea or

Insect Insects (from Latin ') are pancrustacean hexapod invertebrates of the class Insecta. They are the largest group within the arthropod phylum. Insects have a chitinous exoskeleton, a three-part body ( head, thorax and abdomen), three ...

a) by means of a secreted, glue-like basal holdfast. Th
thalli
are coenocytic (i.e. lack divisions within the cell) and are unbranched. Sexual reproduction is unknown

may proceed along two different routes: 1) the entire content of the cell divides into elongated,

uninucleate {{Short pages monitor