Halamphora acutiuscula and H. tumida both have a lower stria density.

LM scalebar = 10 µm
Length Range
15-40 µm
Width Range
5-7 µm
Striae in 10 µm
17-21 at center, 22-24 near apices
Halamphora coffeaeformis LM3
Halamphora coffeaeformis LM6
Halamphora coffeaeformis LM1
Halamphora coffeaeformis LM5
Halamphora coffeaeformis LM7
Halamphora coffeaeformis LM4
Halamphora coffeaeformis LM2
Halamphora coffeaeformis LM3 Halamphora coffeaeformis LM6 Halamphora coffeaeformis LM1 Halamphora coffeaeformis LM5 Halamphora coffeaeformis LM7 Halamphora coffeaeformis LM4 Halamphora coffeaeformis LM2

Halamphora latecostata

Štěpánek and Kociolek 2013

Length Range
16-50 µm
Width Range
4.1-7.9 µm
Striae in 10 µm
9-13 at dorsal center; 15-18 at dorsal apices; 19-20 ventral
Halamphora latecostata LM1 Halamphora latecostata LM6 Halamphora latecostata LM5 Halamphora latecostata LM7 Halamphora latecostata LM2 Halamphora latecostata LM3 Halamphora latecostata LM4

Also compare to

Halamphora tumida

(Hust.) Levkov