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Pinnularia decrescens and Pinnularia undula are larger, lack a central fascia, and lack a strongly curved external raphe slit.

LM scalebar = 10 µm
Pinnularia lailaensis LM6 Pinnularia lailaensis LM5 Pinnularia lailaensis LM4 Pinnularia lailaensis LM3 Pinnularia lailaensis LM1 Pinnularia lailaensis LM7 Pinnularia lailaensis LM8
Length Range
61-79 µm
Width Range
11.1-13.3 µm
Striae in 10 µm
10-11

Pinnularia decrescens

(Grunow) Krammer 2000

Pinnularia decrescens LM3 Pinnularia decrescens LM5 Pinnularia decrescens LM2 Pinnularia decrescens LM1 Pinnularia decrescens LM4 Pinnularia decrescens LM6 Pinnularia decrescens LM7
Length Range
80-93 µm
Width Range
14-17 µm
Striae in 10 µm
9-11

Pinnularia undula

(Schumann) Krammer 2000

Pinnularia undula Pinnularia undula Pinnularia undula Pinnularia undula Pinnularia undula Pinnularia undula
Length Range
63-87 µm
Width Range
15-17 µm
Striae in 10 µm
9-10