Image © Maarten Mandos
Staurastrum monticulosum. Notice subtrapeziform semicells with pairs of spines both at the lateral angles and at the apex.
Cell dimensions (L x B, including spines): ca 50 x 42 µm
A cell of St. monticulosum the semicells of which are hexagonal rather than subtrapeziform in outline. Notice semicell lobes with a vertical pair of spines at the lateral angles and a horizontal pair of spines at the apex.
St. monticulosum belongs to a group of triradiate Staurastra characterized by a cell wall ornamentation consisting of both spines and granules. Cell sinus is widely open from its apex and semicells are subtrapeziform to hexagonal in outline. Lateral angles are truncate and marked by two spines lying in the same vertical plane. Also at the apex of each semicell lobe a pair of similar spines but lying in a horizontal plane and mutually more removed. Cell wall further furnished with a variable number of small, acute granules arranged in concentric series around the angles. In the Netherlands, St. monticulosum is a rare species of oligo-mesotrophic habitats.
Image © Wil Leurs
Empty cell of St. monticulosum showing cencentric series of cell wall granules at the semicell lobes.