Genus Haplomyxa Dellinger, 2014

 

Diagnosis: naked multinucleated cell of various shape, cell body from globular to flat extended shape, usually massive and elongated, may be with few branches and/or holes but not extensively and constantly reticulated, cytoplasm with several alternatively opposite flows, producing a few large and extended pseudopodia (€œveins€) and a network of interconnected filopodia (reticulopodia) all forming from any part of the cell and bearing granules and attached particles circulating bidirectionally (granuloreticulopodia), numerous cytoplasmic granules and contractile vacuoles, migration and division by translation within large pseudopodia, making covered cysts. Freshwater.
Type species: Haplomyxa saranae Dellinger.

Etymology: from the Greek haplo (single, simple) and myxa (slime), to report on its massive shape, different from the reticulated shape of Reticulomyxa.

Other species: at least two other undescribed species reported by N. Hülsmann might be of the same genus (Hülsmann 1984; Kaufmann D, Wylezich C, Hülsmann N (2006) Deutschen Gesellschaft für Protozoologie: Protist Diversity: Past, Present and Future 8-11 March 2006, Liebenwalde, Germany, Abstract KV4) and one species only known by an environmental rDNA sequence reported from Lake Neuchâtel (Switzerland) (Holzmann et al. 2003).

 

 

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. 

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)