Separation spines
In certain species within Aulacoseira, separation spines are formed by some valves, causing the frustules within a chain to break apart. Separation spines are long, in contrast to short, linking spines that join frustules together.
Image Credit: Marina Potapova
Aulacoseira granulata is one of the species that forms separation spines and linking spines. Here, a valve has three separation spines.
Image Credit: Marina Potapova
The separation spines of A. muzzanensis are long and coarse.
Image Credit: Marina Potapova
Separation spines are one of the diagnostic features of A. granulata.