world of amoeboid organisms


Haplomyxa saranae Dellinger, 2014

Diagnosis: cell body from small rounded (0.1 mm) to large elongated shape (up to 3.5 x 0.3 mm), usually flat but may become globular in altered media or when forming cysts, cytoplasm colorless or lightly grey-brownish, may appear dark green or brown due to algal preys, binary -sometimes ternary- division by cytoplasm migration through large pseudopods, cyst usually single or few in a cluster. Multinucleate, with hundreds of small nuclei (2-4 µm) equally spread over the central cell body. In a typical large cell (1300 µm x 75 µm), it was inferred from the analysis of 12% of the cell that the total number of nuclei was about 1800.

Ecology: freshwater pond in Saran, 45770 France (type locality, 2008). Only isolated from the type locality, similar species in Lake Neuchâtel (Switzerland) observed by molecular phylogeny analyses of environmental samples (Holzmann et al. 2003).
Feeding mainly on microalgae. This species was maintained in Volvic® water and fed with Chlorogonium elongatum.

Cell shape and pseudopodial network. A: bright field microscopic image of the first cell observed in the primo-culture (pseudopodia not visible). B: phase-contrast microscopic image of a cultured cell showing an elongated cell body with two main pseudopodia and some smaller ones. C: bright field microscopic image of a of a R. filosa cell. D: image of a dried fixed cell obtained by stitching several dark-field (inverted colors) microscopic images showing the network of pseudopodia radiating from the cell body. Scale bars: 500 m. (from Dellinger et al, 2014)
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