Aulacoseira Muzzanensis Guide
Credit: Marina Potapova
  1. Ratio of mantle height to valve diameter < 1.2
  2. Separation spines long, few
  3. Mantle areolae appear square or oval
  4. Rows of mantle areolae in separation valves straight or curved to right
  5. Rows of mantle areolae often appear biseriate

Valves are 9-24 µm in diameter, with a mantle height of 5-13 µm. The ratio of the mantle height to valve diameter is 0.4-1.2. The mantle areolae are square, but sometimes appear as oval in LM. The rows of are almost straight and parallel to pervalvar axis in separation valves, but often curved to the right in linking valves, 7-15 in 10 µm. Areolae in separation valves are often coarse and disorganized. The straight rows of areolae often appear as biseriate in LM. Linking spines are located at the end of each pervalvar costa. They are short, triangular or bifurcated. Separation spines originate from two pervalvar costae. Most separation spines are 0.5-2 µm long, but some spines are long, almost equal in length to the valve mantle. The ringleiste is solid and moderately shallow. Coiled rimoportulae are usually positioned at the distance of 1-3 areolae from the collum.