Syndinium borgerti

Super Group: 
Hollande, Enjumet & Manciet 1953


Diagnosis_Genus: These parasites were initially confounded with a putative formation of anisospores during sexual reproduction of radiolarian by Hertwig 1879 and Brandt 1885. Chatton 1923 erected a new genus (Merodinium) for all Syndinium-like parasites infesting radiolarian, then separating parasites of copepods  from the ones infecting radiolarian. This separation is based on the mode of infection (intracellular in Merodinium and in the general cavity of copepods), by the earlier fragmentation of the plasmodium in Merodinium, and the shape of their spores (fusiform in Syndinium and piriform for Merodinium). Hollande and Enjumet 1953 kept the genus name Syndinium for all parasites of radiolarian located inside the capusle, and reserved the genus name of Merodinium for all extracapsular parasites. Merodinium and Syndinium were considered as synonymous two years after by Hollande and Enjumet 1955. Delineation of these two genera, if valid, needs to be more studied. Species were mainly separated based upon the identity of their host species.
Diagnosis_Species: S. borgerti Hollande, Enjumet & Manciet 1953. Intracapsular parasite of Aulacantha scolymantha. First stage unknown, but the parasite may penetrate its host by the astropyle (Cachon-Enjumet 1961). Young trophonts intracapsular, forming plasmodium that fragmented. The host nucleus and cytoplasm are digested together with the multiplication of plasmodia.  Sporogenesis end with the formation of two types of spores (macro and microspores), but generally one host provides a single spore type. Spores are released outside the capsule when the latter breacks. V-shaped chromosomes (4 in total). Detected all the year.
Body_macrospores: 18 x 9 µm
Body_microspores: 13 x 5 µm



borgerti: In honour of Pr. Borgert, who first observed sporogenesis of these parasites, thinking to have discovered evidences for sexual reproduction in phaeodarés.

Type illustration / Type locality / Type specimen

Type host: Aulacantha scolymantha
Type locality: Alger Bay


Substrate: endozoic
Salinity: marine

Life cycle

Phases_alternance: haplontic
Generation: <1 month
Reproduction_mode: asexual
Symbiont: horizontal

Feeding behaviour


Mode of locomotion


Observation site(s)


Displaying 1 - 4 of 4
Association with... Region origin Name of site In reference...
Aulacantha scolymantha Alger Bay
Aulacantha scolymantha
Hovasse R, Brown EM (1953) Contribution à la connaissance des radiolaires et de leurs parasites syndiniens. Annales des Sciences Naturelles, Zoologie et Biologie Animale Tome XV:405-437.
Coelodendrum ramosissimum
Cachon-Enjumet M (1961) Contribution à l'étude des radiolaires phaeodariés. Archives de Zoologie Expérimentale et Générale 100:151-238.
Phaeodina valdiviae
Cachon-Enjumet M (1961) Contribution à l'étude des radiolaires phaeodariés. Archives de Zoologie Expérimentale et Générale 100:151-238.