The Mesomycetozoea (or DRIP clade, or Ichthyosporea) are a small group of
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 ...
protist
A protist () is any eukaryotic organism (that is, an organism whose cells contain a cell nucleus) that is not an animal, plant, or fungus. While it is likely that protists share a common ancestor (the last eukaryotic common ancestor), the exc ...
s), mostly
parasite
Parasitism is a close relationship between species, where one organism, the parasite, lives on or inside another organism, the host, causing it some harm, and is adapted structurally to this way of life. The entomologist E. O. Wilson has ...
s of fish and other animals.
Significance
They are not particularly distinctive morphologically, appearing in host tissues as enlarged spheres or ovals containing spores, and most were originally classified in various groups as fungi, protozoa, or colorless algae. However, they form a coherent group on molecular trees, closely related to both
animal
Animals are multicellular, eukaryotic organisms in the Kingdom (biology), biological kingdom Animalia. With few exceptions, animals Heterotroph, consume organic material, Cellular respiration#Aerobic respiration, breathe oxygen, are Motilit ...
s and
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 ...
and so of interest to biologists studying their origins. In a 2008 study they emerge robustly as the sibling-group of the clade
Filozoa
The Filozoa are a monophyletic grouping within the Opisthokonta. They include animals and their nearest unicellular relatives (those organisms which are more closely related to animals than to fungi or Mesomycetozoa).
Three groups are curre ...
, which includes the animals.
Huldtgren et al., following x-ray tomography of
microfossil
A microfossil is a fossil that is generally between 0.001 mm and 1 mm in size, the visual study of which requires the use of light or electron microscopy. A fossil which can be studied with the naked eye or low-powered magnification, ...
Doushantuo Formation
The Doushantuo Formation (formerly transcribed as Toushantuo or Toushantou, from ) is a geological formation in western Hubei, eastern Guizhou, southern Shaanxi, central Jiangxi, and other localities in China. It is known for the fossil Lagerst ...
, has interpreted them as mesomycetozoan spore capsules.
Terminology
The name DRIP is an acronym for the first protozoa identified as members of the group,
Cavalier-Smith
Thomas (Tom) Cavalier-Smith, FRS, FRSC, NERC Professorial Fellow (21 October 1942 – 19 March 2021), was a professor of evolutionary biology in the Department of Zoology, at the University of Oxford.
His research has led to disc ...
later treated them as the class Ichthyosporea, since they were all parasites of fish.
* order Dermocystida
** "D": '' Dermocystidium''. One species, '' Rhinosporidium seeberi'', infects birds and mammals, including humans.
** "R": the "rosette agent", now known as ''
Sphaerothecum destruens
''Sphaerothecum destruens'' (the rosette agent) is a parasite of fish. It was first discovered in the United States in association with invasive species including topmouth gudgeon, but was found to be the causative agent of a disease in the UK ...
''
* order Ichthyophonida
** "I": '' Ichthyophonus''
** "P": '' Psorospermium''
Since other new members have been added (e.g. the former fungal orders Eccrinales and Amoebidiales), Mendoza ''et al.'' suggested changing the name to Mesomycetozoea, which refers to their evolutionary position. On Eukaryota tree, in
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 ...
clade, Mesomycetozoea is in the middle ("Meso-") of the fungi ("-myceto-") and the animals ("-zoea"). Note the name Mesomycetozoa (without a third e) is also used to refer to this group, but Mendoza ''et al.'' use it as an alternate name for basal Opisthokonts.
Phylogeny
Taxonomy
* Class Ichthyosporea Cavalier-Smith 1998
** Order Dermocystida Cavalier-Smith 1998
*** Family Rhinosporidiaceae Mendoza et al. 2001
**** Genus '' Amphibiocystidium'' Pascolini et al. 2003
**** Genus '' Chromosphaera'' Grau-Bové et al. 2017
**** Genus '' Dermocystidium'' Pérez 1908 'Amphibiothecum''_Feldman,_Wimsatt_&_Green,_2005;_''Dermocystis.html" ;"title="Amphibiothecum.html" ;"title="'Amphibiothecum">'Amphibiothecum'' Feldman, Wimsatt & Green, 2005; ''Dermocystis">Amphibiothecum.html" ;"title="'Amphibiothecum">'Amphibiothecum'' Feldman, Wimsatt & Green, 2005; ''Dermocystis'' Pérez 1907 non]
**** Genus ''Dermosporidium'' Carini 1940
**** Genus ''Dermotheca''
**** Genus ''Rhinosporidium'' Minchin & Fantham 1905
**** Genus ''Sphaerothecum'' Arkush et al. 2003 (Rosette agent)
**** Genus '' Valentines (genus), Valentines'' Borteiro et al. 2018
** Order Ichthyophonida Cavalier-Smith 1998 chthyophonae Mendoza et al. 2001; Amoebidiales; Eccrinales Léger & Dubosq 1929*** Suborder Sphaeroformina Cavalier-Smith 2012
**** Family Creolimacidae Cavalier-Smith 2012
***** Genus '' Anurofeca'' Baker, Beebee & Ragan 1999
***** Genus '' Creolimax'' Marschall et al. 2008
***** Genus '' Sphaeroforma'' Jostensen et al. 2002 'Pseudoperkinsus'' Figueras et al. 2000**** Family Psorospermidae Cavalier-Smith 2012
***** Genus '' Psorospermis'' Cavalier-Smith 2012 Psorospermium''_Hilgendorf_1883_non_Eimer_1870.html" ;"title="' Psorospermium'' Hilgendorf 1883 non Eimer 1870">' Psorospermium'' Hilgendorf 1883 non Eimer 1870
**** Family Piridae Cavalier-Smith 2012
***** Genus '' Caullerya'' Chatton 1907
***** Genus '' Abeoforma'' Marshall & Berbee 2011
***** Genus '' Pirum'' Marshall & Berbee 2011
*** Suborder Trichomycina Cavalier-Smith 2012
**** Genus †'' Paleocadus'' Poinar 2016
**** Family Amoebidiidae Lichtenstein 1917 ex Kirk et al. 2001
***** Genus '' Amoebidium'' Cienkowski 1861
**** Family Ichthyophonidae Cavalier-Smith 2012
***** Genus '' Ichthyophonus'' Plehn & Mulsow 1911
**** Family Paramoebidiidae Reynolds et al. 2017
***** Genus '' Paramoebidium'' Léger & Duboscq 1929
**** Family Parataeniellaceae Manier & Lichtward 1968
***** Genus '' Lajassiella'' Tuzet & Manier 1951 ex Manier 1968
***** Genus '' Nodocrinella'' Scheer 1977
***** Genus '' Parataeniella'' Poiss. 1929
**** Family Eccrinaceae Leger & Duboscq 1929 alavasciaceae Manier & Lichtward 1968***** Genus '' Alacrinella'' Manier & Ormières ex Manier 1968
***** Genus '' Arundinula'' Léger & Duboscq 1906 'Arundinella''_Léger_&_Duboscq_1905_non_Raddi_1823.html" ;"title="Arundinella.html" ;"title="'Arundinella">'Arundinella'' Léger & Duboscq 1905 non Raddi 1823">Arundinella.html" ;"title="'Arundinella">'Arundinella'' Léger & Duboscq 1905 non Raddi 1823***** Genus ''Astreptonema'' Hauptfleisch 1895 [''Eccrinella'' Léger & Duboscq 1933]
***** Genus ''Eccrinidus'' Manier 1970
***** Genus ''Eccrinoides'' Léger & Duboscq 1929 'Eccrinopsis''_Léger_&_Duboscq_1916.html" ;"title="Eccrinopsis.html" ;"title="'Eccrinopsis">'Eccrinopsis'' Léger & Duboscq 1916">Eccrinopsis.html" ;"title="'Eccrinopsis">'Eccrinopsis'' Léger & Duboscq 1916***** Genus ''Enterobryus'' [''Andohaheloa'' Manier 1955; ''Capillus (genus), Capillus'' Granata 1908; ''Cestodella'' Tuzet, Manier & Jolivet 1957; ''Daloala'' Tuzet, Manier & Vog.-Zuber 1952; '' Eccrina'' Leidy 1852; '' Lactella'' Maessen 1955; '' Paratrichella'' Manier 1947; '' Pistillaria'' Jeekel et al. 1959 non Fries 1821; '' Recticoma'' Scheer 1935; '' Trichella'' Léger & Duboscq 1929; '' Trichellopsis'' Maessen 1955]
***** Genus '' Enteromyces'' Lichtwardt 1961
***** Genus ''
Enteropogon
''Enteropogon'' is a genus of tropical and subtropical plants in the grass family. It is widespread across many parts of Asia, Africa, Australia, the Americas, and various islands.Leidyomyces'' Lichtwardt et al. 1999
***** Genus '' Palavascia'' Tuzet & Manier 1947 ex Lichtwardt 1964
***** Genus '' Paramacrinella'' Manier & Grizel 1971
***** Genus '' Passalomyces'' Lichtwardt et al. 1999
***** Genus '' Ramacrinella'' Manier & Ormiéres 1962 ex Manier 1968
***** Genus '' Taeniella'' Léger & Duboscq 1911
***** Genus '' Taeniellopsis'' Poisson 1927