Copromyxa microcystidis Van Wichelen & Vanormelingen, 2016

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 : 82

Copromyxa microcystidis Van Wichelen & Vanormelingen sp. n.

Diagnosis: Locomotive amoebae limax-shaped, 20– 59 µm long and 7–17 µm wide with anteriorly a well pronounced hyaline cap. Monopodial movement eruptive-like by means of alternating lateral sprouting lobes regularly adopting a bipodial or multipodial state. Vesicular oval nucleus of 5–10 µm in diameter with one central to slightly eccentrically placed globular nucleolus. Usually one, rarely up to 3 small contractile vacuoles present posteriorly. The cytoplasm always contains up to 22 opaque crystals and several smaller, refractive spheres. Floating form spherical with a diameter of 15–20 µm and radially displaying up to 10 small hyaline lobes. Cysts spherical with a diameter of maximally 20 µm.

Feeding behavior: It feeds voraciously on Microcystis aeruginosa . Other Microcystis morphotypes ( M. viridis , M. wesenbergii ), heterotrophic bacteria and green algae ( Acutodesmus ) were not ingested (Van Wichelen, unpublished).

Type material: Strain A2 JEPDK is available from the NIES Microbial Culture Collection (NIES-3723). The 18 S rDNA GenBank accession number is KP719188 .

Type locality: Isolated from a Microcystis bloom sample originating from a mesocosm in Silkeborg ( Denmark) ( Table 1) .

Etymology: microcystidis referring to Microcystis , its main food.

Differential diagnosis: Morphologically, C. microcystidis differs slightly from the next species ( C. vandevyveri ) by its more eruptive-like pseudopodium formation, its smaller, more globular subpseudopodia during non-oriented movement and the presence of large crystals in the cytoplasm. Also its 18 S rDNA sequence distinguishes it from C. vandevyveri .