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SYNOPTIC DESCRIPTION OF PHYLUM ENDOMYXA

SYNOPTIC DESCRIPTION OF PHYLUM ENDOMYXA

EUKARYA> CHROMALVEOLATA> RHIZARIAE> ENDOMYXA
ENDOMYXA LINKS

Introduction

Hierarchical Classification

Descriptions of the phylum come from Kudo (1966), Grell (1976), Cachon et al. (1990), Febvre (1990), Febvre-Chevalier (1990), Patterson (1999), Swale and Belcher 1974, Beech and Moestrup 1986; Patterson and Zolffel 1991, Dylewski (1990), Margulis and Schwartz (1998), and Sleigh et al. (1984).

I. SYNONYMS: Sarcodina (some), radiolaria (some), amoboeflagellates (some), heliozoans (some). The parasitic forms are known as Plasmodiophorids, plasmodiophoromycota, endoparasitic slime molds, phytomyxea, Sporozoans, acetosporans, ascetosporeans..

II. NUMBER: > 1,000 species?

III. PHYLUM CHARACTERISTICS

  • A. Structure
    • Cell Form: Unicells that may have radiating, filose pseudopods, parasitic forms tend to be plasmodial. Some taxa have flagellated spores.
    • Flagella: Zoospores (text with tooltip) A zoospore is an asexual spore that is motile. Zoo- (pronoumced zo-o) is a prefix that means moving. (when present) with unequal, whiplash flagella (text with tooltip) (1) A whiplash flagellum is a eukaryotic 9+2 flagellum with few or no flagellar hairs or scales. These may be directed anteriorly or posteriorly. (2) A whiplash flagellum is free of hair-like mastigonemes and usually is trailing or posteriorly-directed. ; the shorter flagellum is directed anteriorly (text with tooltip) An anteriorly-directed flagellum extends in the direction of the motion of the motile cell. The interpretation is that the flagellum functions by pulling the cell. and the longer flagellum is directed posteriorly (text with tooltip) Recurrent flagella bend to the posterior end of the cell. Typically, they are identified as recurrent when anteriorly-directed flagella are present. .
    • Basal Bodies: Variable; 45 – 60 degrees
    • Cell Covering : Generally naked; cyst covering of polysaccharide other than cellulose; probably chitin; some with organic test. Haplosporidians have distinctive spore with a lid.
    • Chloroplasts: Not present
    • Food Reserves: Not known
    • Mitochondria: Present with tubular cristae (text with tooltip) Mitochondrial cristae that form as extended saccate structures or tubes are called tubular cristae. .
    • Golgi (text with tooltip) Golgi apparatus (also called dictyosome) is an internal membrane system of stacked flattened sacs. They occur in nearly all eukaryotes and are involved in storing and secreting cellular products. : Present.
    • Nucleus: Many are plasmodial (multinucleate); some with cruciform division (text with tooltip) Cruciform division is a cross-like appearance of the nucleus during metaphase in the plasmodiophorotists. The appearance of a cross comes from an elongate nucleolus perpendicular to the direction of the movement of the chromosomes in closed division. . Haplosporidians with persistent spindle in all non dividing cells.
    • Centrioles: Present
    • Inclusions and Ejectile Organelles: Food vacuoles?
  • B. Mitosis, Meiosis and Life History
    • Mitosis: Likely closed (text with tooltip) Mitosis is closed when the segregation of daughter chromosomes occurs within the bounds of the nuclear membrane (the nuclear membrane does not break down). with intranuclear spindle (text with tooltip) An intranuclear spindle elaborates within the nuclear membrane of an organism with closed mitosis. . Plasmodiophorids have an unusual method of chromosome segregation called cruciform division (chromatin divides in a clump and moves to the poles while the nucleolus elongates).
    • Meiosis: Nuclei become invisible (akaryotic) during meiosis. Not described for most groups.
    • Sexual Reproduction and Life History: Complex in the parasitic forms; poorly known for the free-living taxa. Plasmodiophorans: Life cycle is complex with haploid and diploid plasmodia and secondary zoospores which function as isogametes (text with tooltip) Isogametes are gametes that are equal in size. . Haplosporidians may have a sexual life history.
  • C. Ecology: Many are intracellular parasites of plants and animals. Free-living taxa feed on bacteria, detritus, algae, and other eukaryotes; mostly associated with substrates.
LITERATURE CITED

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By Jack R. Holt. Last revised: 03/05/2013
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