Cosmarium paragranatoides. Notice pyramidal semicell outline and faintly undulate lateral sides.

Cell dimensions (L x B): 29 x 19 µm

Empty cell of C. paragranatoides showing a relatively thick cell wall.

A slightly distorted, empty cell of C. paragranatoides focussed on its cell surface showing evenly distributed, coarse scrobiculae and a protuberance in the semicell centre.



Desmid of the month
November 2021

Cosmarium paragranatoides

Cosmarium paragranatoides somewhat resembles C. granatoides. Apart from a slightly different semicell outline (more pyramidal, with less deep marginal incurvations than in C. granatoides), the main diagnostic feature in C. paragranatoides is its relatively thick, coarsely scrobiculate cell wall provided with a distinct protuberance in about the centre of the semicell. In the Netherlands, C. paragranatoides is of occasional occurrence in slightly acidic, mesotrophic fen hollows.

SEM picture of C. paragranatoides showing that cell wall scrobiculae are lacking in the periphery and the central protuberances.