Angulamoeba

Van Wichelen, Jeroen, D’Hondt, Sofie, Claeys, Myriam, Vyverman, Wim, Berney, Cédric, Bass, David & Vanormelingen, Pieter, 2016, A Hotspot of Amoebae Diversity: 8 New Naked Amoebae Associated with the Planktonic Bloom-forming Cyanobacterium Microcystis, Acta Protozoologica 55 (2), pp. 61-87 : 76

Angulamoeba

In the Angulamoeba ML phylogeny ( Fig. 8A ), the additional reticulate strains (A4 WVB, A7 WVB) and sequences (A1 WVB, A2 WVB) were situated in the same lineage as the already published Angulamoeba microcystivorans sequences ( Van Wichelen et al. 2010, Berney et al. 2015). A. microcystivorans sequences differed by 0.0–0.3% (0–3 bp) from each other. The nearest other sequence, obtained from a natural sample, differed by 6.6–7.5% (65–111 bp) from A. microcystivorans .

The trophozoites of all our strains were elongated, deeply inclined, sometimes seemingly connected with filopodia, and became aggregated into a plasmodiumlike mucilage matrix at high population densities. They had an amoeboflagellate (1–3 flagella) and a cyst stage ( Fig. 8B ) and fed voraciously on Microcystis , resulting in the clearance of Microcystis cultures in a matter of days.

The morphology and 18S rDNA sequence of our strains were similar to our previously studied strain A1 WVB isolated from the same bloom sample and newly described as Angulamoeba microcystivorans ( Berney et al. 2015) . We thus concluded they belonged to this species as well.

Figures

Fig. 8. A – 18S rDNA maximum likelihood phylogeny of Angulamoeba. Sequences new for this study are indicated in bold. ML bootstrap values respectively posterior probabilities are shown at the nodes. GenBank accession numbers are given together with the species names. B – LM pictures of Angulamoeba microcystivorans (strains A1WVB (1, 2, 4) and A4WVB (3)) showing the characteristic rusty-colored plasmodium-like mucilage matrix with embedded trophozoites devouring a culture of Microcystis aeruginosa colonies (1–2), multi-vacuolated trophozoites that are seemingly connected by their filopodia (3) and amoeba-flagellates in different stages of transition (4). Scale bars: 200 µm (1), 100 µm (2), 20 µm (3, 4).