Pinaciophora fluviatilis
P. fluviatilis, note the perforated plate scales in lateral view.

Pinaciophora fluviatilis Greeff, 1873 sensu Penard, 1904

Diagnosis: Cells spherical to ovoid with a diameter ranging from 45-50 µm. The plate-scales are circular, discoid, 4-6 µm in diameter; they are flat and have commonly a distinct hexagonal pattern of large boles. 17-24 in number, mostly arranged in a regular 3-4-5-4-3 or a 4-5-6-5-4 sequence. Smaller perforations are irregularly distributed along the periphery. Nucleus relatively large, finely granulated with a larger granule in the center.

Ecology: Freshwater; oligotrophic and mesotrophic water-types; between water plants and in sediment of shallow waters. In lakes, marshes, canals, ditches streams and rivers. Consuming detritus and algae. Reported from Germany Greeff, 1873, Rainer, 1968), Scandinavia (Thomsen, 1978), United Kingdom (Belcher and Swale, 1978), the Netherlands (Siemensma, 1991), Peru, Texas (Gaarder et al., 1976), Antarctica (Takahashi, 1981).
I found it at several locations, e.g. a small fountain fed by a small natural stream (Royal Palace het Loo), in a large lake, the IJsselmeer, near Kornwerderzand, in another lake, the Spiegelplas, and a shallow ditch in Gaasterland, all in the Netherlands.

Pinaciophora fluviatilis
P. fluviatilis
Pinaciophora fluviatilis
Pinaciophora fluviatilis, dried specimen – the Netherlands, SEM photomicrograph Eckhard Voelcker
Pinaciophora fluviatilis
Pinaciophora fluviatilis, plate scales – the Netherlands, SEM photomicrograph Eckhard Voelcker
Pinaciophora fluviatilis
Pinaciophora fluviatilis, plate scale – the Netherlands, SEM photomicrograph Eckhard Voelcker
Pinaciophora fluviatilis
Pinaciophora fluviatilis, plate scale with structure of the basal plate – the Netherlands, SEM photomicrograph Eckhard Voelcker
Pinaciophora fluviatilis
Pinaciophora fluviatilis – after Siemensma, 1991: b-c TEM-photomicrographs of plate-scales – drawing: Ferry Siemensma; TEM: Rudy Roijackers
Pinaciophora fluviatilis
Pinaciophora fluviatilis
Scale after Thomsen 1978; Relatively large nucleus and small nucleolus
Habitus
Holes in the scales as seen by light microscopy
Pinaciophora fluviatilis
P. fluviatilis
Pinaciophora fluviatilis
Pinaciophora fluviatilis, note the perforated plate scales
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