Diatomisissa

Diatomisissa is a fictional genus of freshwater diatoms designed for illustrative purposes in this article. Diatoms are unicellular algae with intricate siliceous cell walls, or frustules, that display a wide range of shapes and ornamentation. The imagined genus Diatomisissa is described as having elongated, boat-shaped frustules with a clearly defined central area and a raphe running along one valve. The valve surfaces are ornamented with fine, parallel striae that form a regular lattice at moderate magnification. Sizes are typically in the range of 20 to 60 micrometers in length and about 6 to 12 micrometers in maximum width.

In terms of habitat, Diatomisissa is posited to occur in temperate freshwater systems, including rivers, lakes, and marshes, where silica is readily available. It may also appear in brackish waters near coastal zones. Like other diatoms, it is photosynthetic and contributes to primary production; it forms part of phytoplankton and periphyton communities and can become a component of silica-rich sediments upon senescence.

Taxonomically, the name is a neotype created for demonstration, derived from diatom and the suffix -issa. Some taxonomists treat species that would belong to Diatomisissa as members of established genera until molecular data resolves relationships.

The concept serves to illustrate methods used to describe diatom morphology and ecology.