Aulacoseira pusilla has one spine for every two costae.

Aulacoseira distans has a lower density of mantle rows of areolae, the valve face is covered by areolae, a deep ringleiste is present, and numerous (4-12) prominent rimoportulae are visible in LM in valve view. Note that A. distans has not been documented in modern material; it is considered to be extinct.

LM scalebar = 10 µm
Aulacoseira alpigena LM2 Aulacoseira alpigena LM1 Aulacoseira alpigena LM4 Aulacoseira alpigena LM3 Aulacoseira alpigena LM5 Aulacoseira alpigena LM6 Aulacoseira alpigena LM7
4-15 µm
Width Range
4-7 µm
Striae in 10 µm

Aulacoseira pusilla

(Meister) Tuji and Houki 2004

Aulacoseira pusilla LM3 Aulacoseira pusilla LM4 Aulacoseira pusilla LM5 Aulacoseira pusilla LM6 Aulacoseira pusilla LM1 Aulacoseira pusilla LM2
4.5-7.5 µm
Width Range
2.2-4.5 µm
Striae in 10 µm

Also compare to

Aulacoseira distans

(Ehrenb.) Simonsen