Cavinula cocconeiformis

(Gregory ex Grev.) D.G.Mann and Stickle in Round, R.M.Crawford and D.G.Mann 1990      Category: Symmetrical biraphid
BASIONYM: Navicula cocconeiformis Gregory ex Grev. 1855

Capartogramma crucicula


Cavinula davisiae

LM scalebar = 10 µm = 80 pixels.


Contributor: Megan Otu | Sarah Spaulding - March 2011
Length Range: 9-28 µm
Width Range: 6-9 µm
Striae in 10 µm: 26-32 in the center valve, 28-34 at the ends


Valves are lanceolate in larger specimens to elliptical at the small end of the size range. The apices are narrowly to broadly rounded. The axial area is narrow and linear and extends onto the valve margins at the apices. The central area is oval in large valves, becoming linear-lanceolate in smaller valves. The raphe is filiform with expanded central fissures. The terminal raphe fissures are deflected to the same side. The striae are punctate and radiate. In the central valve, several striae are short do not extend from the central area to the valve margin. The stria density increases slightly towards the apices. The external expressions of the areolae are oval, except at the central area where they are elongated in the transapical axis. The areolae bordering the central area are elongated to a greater extent than the other areolae (SEM). Internally, the areolae are slightly elongated. Internally, the raphe slit is narrow at the proximal and terminal fissures. Helictoglossae are reduced.

Original Description

Basionym: Navicula cocconeiformis
Author: Gregory ex Grev. 1855
Length Range: µm
Striae in 10 µm:

Original Description

Navicula cocconeiformis, Greg. MS. Pl. IX. fig. 6. Length .0008” to .0011”. Navicula nugax, W. Sm. MSS. A new species, somewhat similar in outline to Achnanthidium flexellum, with striae so fine that I have not succeeded in resolving them. I find that this species has been known for above a year to Professor Gregory, who had both sketched and named it previous to my detection of it in the Braemar gatherings. He had obtained it from Elchies and various other places in Banffshire, and latterly from Loch Leven.

Original Images

Cite This Page:
Otu, M., and Spaulding, S. (2011). Cavinula cocconeiformis. In Diatoms of the United States. Retrieved April 21, 2018, from

Species: Cavinula cocconeiformis

Contributor: Megan Otu | Sarah Spaulding

Reviewer: Pat Kociolek


Greville, R.K. (1855). Report on a collection of Diatomaceae made in the district of Braemar by Professor Balfour and Mr. Gerge Lawson. Annals and Magazine of Natural History, 2nd series, 15:252-261.

McGowan, S., Grauertb M. and Anderson, N.J. (2008). A late holocene record of landscape degradation from Heygsvatn, the Faroe Islands . Palaeogeography, Palaeoclimatology, Palaeoecology 264 (1-2): 11-24 . 10.1016/j.palaeo.2008.03.003

Round, F.E., Crawford, R.M. and Mann, D.G. (1990). The Diatoms. Biology and Morphology of the Genera. Cambridge University Press, Cambridge, 747 pp.

Links & ID's

Index Nominum Algarum (INA)

Transfer INA

California Academy of Sciences (CAS)

Cavinula cocconeiformis CAS

North American Diatom Ecological Database (NADED)

NADED ID: 195001

Autecology Discussion

EMAP Assessment

The Environmental Protection Agency (EPA) western Environmental Monitoring and Assessment Program (EMAP) study was completed during the years 2000-2004 (see citations at bottom of this page). Over 1200 streams and rivers in 12 western states (Arizona, California, Colorado, Idaho, Montana, Nevada, North Dakota, Oregon, South Dakota, Utah, Washington and Wyoming) were selected for sampling based on a stratified randomized design. This type of design insures that ecological resources are sampled in proportion to their actual geographical presence. Stratified randomized design also allows for estimates of stream length with a known confidence in several “condition classes” (good or least-disturbed, intermediately-disturbed, and poor or most-disturbed) for biotic condition, chemistry and habitat.

EMAP Distribution

Cavinula cocconeiformis

EMAP Response Plots

Cavinula cocconeiformis

EMAP citations

Results are published in:

Johnson, T., Hermann, K., Spaulding, S., Beyea, B., Theel, C., Sada, R., Bollman, W., Bowman, J., Larsen, A., Vining, K., Ostermiller, J., Petersen, D. Hargett, E. and Zumberge, J. (2009). An ecological assessment of USEPA Region 8 streams and rivers. U.S. Environmental Protection Agency Region 8 Report, 178 p.

Stoddard, J. L., Peck, D. V., Olsen, A. R., Larsen, D. P., Van Sickle, J., Hawkins, C. P., Hughes, R. M., Whittier, T. R., Lomnicky, G. A., Herlihy, A. T., Kaufman, P. R., Peterson, S. A., Ringold, P. L., Paulsen, S. G., and Blair, R. (2005). Environmental Monitoring and Assessment Program (EMAP) western streams and rivers statistical summary. U.S. Environmental Protection Agency Report 620/R-05/006, 1,762 p.

Stoddard, J. L., Peck, D. V., Paulsen, S. G., Van Sickle, J., Hawkins, C. P., Herlihy, A. T., Hughes, R. M., Kaufman, P. R., Larsen, D. P., Lomnicky, G. A., Olsen, A. R., Peterson, S. A., Ringold, P. L., and Whittier, T. R. (2005). An ecological assessment of western streams and rivers. U.S. Environmental Protection Agency Report 620/R-05/005, 49 p.