Tryblionella gracilis

W.Sm. 1853      Category: Nitzschioid
SYNONYM(S): Nitzschia tryblionella Hantzsch 

Tryblionella calida


Tryblionella hungarica

LM scalebar = 10 µm = 40 pixels.


Contributor: Jacob Lister - June 2016
Length Range: 79-117 µm
Width Range: 20-24 µm
Striae in 10 µm: 32-34


Valves are linear-lanceolate and gradually taper to apices that are cuneate to sometimes slightly rostrate. The raphe is keeled and eccentric, fibulae 6-8 in 10 µm. The raphe is slightly constricted at the central nodule. A longitudinal undulation is located along the apical axis of the valve. Costae at the apices are easily distinguishable (6-8 in 10 µm), while costae near the valve center may appear thinner and less pronounced (7-11 in 10 µm). Costae may appear slightly curved and non-parallel across the valve undulation. Striae are difficult to observe with light microscopy.

The original description of Tryblionella gracilis by W. Smith (1853) is valid and legitimate. The taxon was renamed Nitzschia tryblionella Hantzsch in Rabenhorst when it was transferred to Nitzschia by Hantzsch in Rabenhorst 1848-1860. The change in the specific epithet was necessary because the name N. gracilis was already occupied. When the genus Tryblionella was resurrected by Round et al. (1990), the original name Tryblionella gracilis W. Smith 1853 was again recognized as the valid and legitimate name of this taxon.

Original Description

Author: W.Sm. 1853
Length Range: 23-75 µm
Striae in 10 µm:

Original Description

  1. Tryblionella gracilis, n. sp. F.V. linear, attenuate towards the extremitics; V. linear acuminate ; canaliculi parallel, extending to the central line, 10 to 12 in.001” ; alae distinct. Length .0023” to 0075”. v.v. Fresh and brackish water. Near Lewes, Dec. 1850, and Oct. 1852, W. Sm. Plate X. 75. Frustule with endochrome, Frontispiece, fig. LXXV.

Original Images

Cite This Page:
Lister, J. (2016). Tryblionella gracilis. In Diatoms of the United States. Retrieved April 22, 2018, from

Species: Tryblionella gracilis

Contributor: Jacob Lister

Reviewer: Mark Edlund


Hofmann, G., Werum, M. and Lange-Bertalot, H. (2011). Diatomeen im Süßwasser-Benthos von Mitteleuropa. Koeltz Scientific Books, Königstein, 908 pp.

Krammer, K. and Lange-Bertalot, H. (1988). Bacillariophyceae. 2. Teil: Bacillariaceae, Epithemiaceae, Surirellaceae. In: Ettl, H., J. Gerloff, H. Heynig and D. Mollenhauer (eds.) Susswasserflora von Mitteleuropa, Band 2/2. Gustav Fisher Verlag, Jena.

Rabenhorst, L. (1848). Die Algen Sachsens. Resp. Mittel-Europa’s Gesammelt und herausgegeben von Dr. L. Rabenhorst, Dec. 1-100. No. 1-1000. Dresden. [Exsiccata, issued at various dates]. Dec. 1-100. No. 1-1000. Dresden. [Exsiccata, issued at various dates].

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.

Smith, W. (1853). Synopsis of British Diatomaceae. John Van Voorst, London 1853. 89 pp., pls 1-31.

Witkowski, A., Lange-Bertalot, H. and Metzeltin, D. (2000). Diatom Flora of Marine Coasts I. Iconographia Diatomologica 7: 1-925.

Links & ID's

Index Nominum Algarum (INA)


California Academy of Sciences (CAS)

Tryblionella gracilis CAS

North American Diatom Ecological Database (NADED)

NADED ID: 185001

Autecology Discussion

Tryblionella gracilis was found in an epiphytic sample taken in Beck’s Canal, Dickinson County, Iowa, a site with slightly basic water (pH 8.05). Additionally, T. gracilis specimens in the Reimer Herbarium were collected in a benthic sample from Lazy Lagoon, Dickinson County, Iowa. Tryblionella gracilis is found in a variety of habitats: coastal, brackish, and fresh water. (Hofmann et al. 2011).


Distribution of Tryblionella gracilis in rivers of the continental U.S. based on the National Water Quality Assessment program. Retrieved 10 June 2016.

Credit/Source: USGS BioData

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

Tryblionella gracilis

EMAP Response Plots

Tryblionella gracilis

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.