Keppenodinium mycetoides

Super Group: 
Alveolata
Phylum: 
Dinophyta
Sub-Phylum: 
Dinozoa
Class: 
Syndinea
Order: 
Syndiniales
Family: 
Euduboscquellidae
Genus: 
Keppenodinium
Species: 
mycetoides
Authority: 
Loeblich & Loeblich 1966 (Cachon 1964)
Synonym(s): 
Hollandella mycetoides Cachon 1964

Diagnosis

Diagnosis_Genus: The trophont develops inside the endoplasm of its host (Radiolaria, Polycystinea, Spumellarida). Chromosomes have a normal appareance at this stage. Digitations of the cytoplasm are formed. A small structure, likely homologous to the lamina pharyngea in Euduboscquella, is formed at the external part of one of these digitations. Sporulation develops inside the ectoplasm, and starts when one or more digitations pass through the host shell. During sporulation, chromosomes have a V-shaped appearance.

Diagnosis-Species: The trophont develops inside the endoplasm as a plasmodium (several nuclei are produced). Young trophonts have 10 x 5-6 µm, rounded in one pole. The host nucleus is rapidly digested, whilst the ectoplasm remains intact as well as the pseudopods. Thus, infection at this stage cannot be observed directly without a specific coloration. The trophont forms digitations located at all possible aperture within the radiolarian skeleton (but remaining inside the endoplasm), and nuclei are located at the apex of these digitations. Eosinophylic elongated structure present in mature trophont. Sporulation starts when one digitation (never the one associated with the lamina pharyngea) develops inside the ectoplasm. The sporont elongates, until 200 µm long, in the host cytoplasm. It looks like to a long cylindrical pedoncul ends by a dilated apical end. All nuclei migrate to this apex, but only one of them, the first to reach this apex, will sporulate (all other will degenerate). An external membrane is produced, and the pedoncul is separated from the rest of the plasmodium remaining inside the endoplasm, which degenerates. The sporont, now uninucleated, become piriform. Number of V-shaped chromosomes= 8. Successive mitoses occur (at least five generations in total) and each daughter cell divides rapidly. Sporocytes (stage 32) have a lemon-like appearance, surrounded by 5-8 several furrows, with 2-3 of them interrupted by two small flagella.Sporocytes after five generations (32 cells) have 30-35 µm long.
More than one sporont (until six) at different maturation stages could be observed within the same host: they correspond the multiple infections from different individuals.

Type species

This is the type species of the genus.

Type illustration / Type locality / Type specimen

Type host: Spongosphaera

Ecology

Sociability_sporont: solitary
Sociability_sporont: sometime gregarious
Sociability_trophont: plasmodium

Substrate: endozoic
Salinity: marine

Life cycle

Generation: <1 month
Reproduction_mode: asexual
Symbiont: horizontal

Feeding behaviour

Osmotrophy
Parasitism

Mode of locomotion

Flagellum: 2

Observation site(s)

Observation site(s)

HOSTS

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Association with... Region origin Name of site In reference...
Spongosphaera

SYMBIONTS

ASQME static network (beta)

ASQME dynamic network (beta)

ASQME map (beta)