Craticula acidoclinata

Lange-Bert. and Metzeltin 1996      Category: Symmetrical biraphid

Craticula accomodiformis


Craticula ambigua

LM scalebar = 10 µm = 20 pixels.


Contributor: Loren Bahls - June 2012
Length Range: 94-168 µm
Width Range: 22-29 µm
Striae in 10 µm: 12-14


Valves are lanceolate with weakly protracted (subrostrate) and broadly rounded apices. The axial area is narrow and widens gradually into the central area, which is longitudinally elongate with convex sides. The raphe is weakly lateral with proximal ends that are moderately distant, somewhat inflated and hooked to the same side. Striae are weakly radiate but convergent very near the apices. Areolae are easily distinguished in LM and number 23-24 in 10 µm. Craticula are present in some specimens.

Original Description

Author: Lange-Bert. and Metzeltin 1996
Length Range: 60-110 µm
Width Range: 16-23 µm
Striae in 10 µm: 13-15

Original Description

Original Images

Cite This Page:
Bahls, L. (2012). Craticula acidoclinata. In Diatoms of the United States. Retrieved April 26, 2018, from

Species: Craticula acidoclinata

Contributor: Loren Bahls

Reviewer: Steve Main


Lange-Bertalot, H. (2001). Navicula sensu stricto, 10 genera separated from Navicula sensu lato, Frustulia. Diatoms of Europe 2: 1-526.

Lange-Bertalot, H. and Metzeltin, D. (1996). Indicators of oligotrophy - 800 taxa representative of three ecologically distinct lake types, Carbonate buffered - Oligodystrophic - Weakly buffered soft water. Lange-Bertalot, H. (ed.), Iconographia Diatomologica. Annotated Diatom Micrographs. Vol. 2. Ecology, Diversity, Taxonomy. Koeltz Scientific Books. Königstein, Germany, 2:390 pp.

Links & ID's

Index Nominum Algarum (INA)

California Academy of Sciences (CAS)

Craticula acidoclinata CAS

North American Diatom Ecological Database (NADED)

NADED ID: 21037

Autecology Discussion

Craticula acidoclinata is uncommon in small ponds and pools in the Northern Rockies. The Montana population pictured here was found in a small pond in a conifer forest at 2,000 m elevation along the Continental Divide near Helena. The pH of this pond measured 6.98 and specific conductance measured 46 µS/cm. These low pH and specific conductance values distinguish this species ecologically from Craticula cuspidata, which prefers more alkaline water with higher electrolyte content. Craticula acidoclinata was described from an oligo-dystrophic lake in Finland with a pH of 6.5 and a specific conductance of 17 µS/cm.