Ichthyosporea
Parasitic opisthokonts bridging the gap between animals and fungi.
The Ichthyosporea (also known as the DRIP clade or Mesomycetozoea) are a small group of Opisthokonta within Eukaryota, formerly classified as protists. They are mostly parasites of fish and other animals, appearing in host tissues as enlarged spheres or ovals containing spores. Originally placed in various groups as fungi, protozoa, or colorless algae, they form a coherent group on molecular trees and are closely related to both animals and fungi, making them of interest to biologists studying the origins of these kingdoms.
- classification
- Class Ichthyosporea (Opisthokonta, Eukaryota)
- also_known_as
- DRIP clade, Mesomycetozoea
- typical_hosts
- Fish and other animals
- morphology
- Enlarged spheres or ovals containing spores
- evolutionary_position
- Sibling-group of Filozoa (including animals) per a 2008 study
- notable_member
- Rhinosporidium seeberi (infects birds and mammals, including humans)
Quick Facts
- Taxon
- Ichthyosporea
- Subdivision
- Dermocystida / Ichthyophonida
Facts from the source article.
Lore & Background
The group was originally recognized through the DRIP acronym, standing for the first protozoa identified as members: Dermocystidium, the 'rosette agent' (Sphaerothecum destruens), Ichthyophonus, and Psorospermium. Cavalier-Smith later treated them as the class Ichthyosporea, reflecting that all were parasites of fish. Subsequent additions, including the former fungal orders Eccrinales and Amoebidiales, led Mendoza et al. to propose the name Mesomycetozoea, referring to their evolutionary position in the middle ('Meso-') of fungi ('-myceto-') and animals ('-zoea').
Reader's Guide
The Ichthyosporea hold significance primarily as a phylogenetic bridge between animals and fungi. Their placement within Opisthokonta, closely related to both kingdoms, makes them crucial for understanding the evolutionary origins of animals. Although morphologically unremarkable—appearing as spore-filled spheres or ovals in host tissues—their molecular coherence has clarified relationships that were obscured by their former classification as fungi, protozoa, or colorless algae. The group includes parasites of fish and other animals, with one species, Rhinosporidium seeberi, capable of infecting birds and mammals, including humans. The interpretation of Ediacaran microfossils as mesomycetozoan spore capsules suggests a deep evolutionary history. The ongoing refinement of their taxonomy, including the addition of former fungal orders and the alternative naming conventions (DRIP, Ichthyosporea, Mesomycetozoea), reflects the dynamic nature of protist classification and the importance of molecular phylogenetics in resolving such groups.
Did You Know?
- The name DRIP is an acronym for the first protozoa identified as members: Dermocystidium, the rosette agent (Sphaerothecum destruens), Ichthyophonus, and Psorospermium.
- One species, Rhinosporidium seeberi, infects birds and mammals, including humans.
- Huldtgren et al. interpreted microfossils from the Ediacaran Doushantuo Formation as mesomycetozoan spore capsules.
- The name Mesomycetozoea refers to their evolutionary position in the middle of fungi ('-myceto-') and animals ('-zoea').
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