Raphidocystis tubifera Penard, 1904
Diagnosis: Periplast 10-27 µm in diameter, with tangential plate-scales and radial spine-scales. Spine-scales of two kinds: short spine-scales broadly funnel-shaped, 2.5-4.5 µm high, about 2.8 µm in diameter with a thick, hollow rim, and long spine-scales 15-27 µm high, trumpet-shaped or only slightly enlarged distally. All spine-scales with a hollow stem and a button-like base. Sometimes there are a few short spine-scales with only a cup-shaped depression. Plate-scales oval, 5.0-7.9 x 2.5-3.2 µm, with a thick border and a median line. Plate-scales and short spine-scales with a reticulate structure. The number of long spine-scales can vary greatly.
Ecology: Freshwater, mesotrophic waters. Never en masse, all year round. Switzerland (Penard 1904), Great Britain (Wailes 1939), Germany (Rainer 1968), Netherlands (Siemensma 1991), Canada (Rees et al. 1980), New Zealand, Malaysia, Chile, Sri Lanka (Nicholls and Dürrschmidt 1985).