Tryblionella apiculata

Gregory 1857      Category: Nitzschioid
BASIONYM: Tryblionella apiculata Gregory 1857
SYNONYM(S): Nitzschia apiculata (Gregory) Grunow 1878 
REPORTED AS: Nitzschia constricta (Krammer and Lange-Bertalot, 1988, Taf. 15, Figs 1-6) 

Thalassiosira weissflogii


Tryblionella calida

LM scalebar = 10 µm = 80 pixels.


Contributor: Marge Penton - June 2013
Length Range: 39-47 µm
Width Range: 5-7 µm
Striae in 10 µm: 15-17


Valves are linear and constricted in the middle. The ends are expanded, so that the valves are panduriform in shape. The apices are protracted and apiculate to subcapitate. A longitudinal fold is present along the the length of the axial area. On some valves, the fold appears as lack striae, or ghost striae may be apparent. The ratio of striae to fibulae is 1:1, and they can be seen to align with one another. The raphe is eccentric. Although a central nodule is present, it is not always easily seen.

Krammer and Lange-Bertalot (1988, pg. 43) report species as Nitzschia constricta (Kützing) Ralfs in Pritchard 1861 non (Gregory) Grunow in Cleve and Grunow 1880. This taxon has also been referred to as Tryblionella constricta Gregory 1855 in some references. Note that Mann (1990) transferred Nitzschia constricta to Psammodictyon constrictum (Gregory) Mann, but that P. constrictum is a marine taxon quite different from T. apiculata.

Original Description

Basionym: Tryblionella apiculata
Author: Gregory 1857
Length Range: 38-43 µm
Striae in 10 µm: 17-18

Original Description

Form linear, narrow, slightly constricted in the middle; extremities apiculate. Keel strongly marked in many specimens, striae fine but distinct, about 45 in 0.001”. Length 0.0015” to 0.0017”. The striation is peculiar, for in many species it is easy to see not only transverse, but oblique striae.

Original Images

Cite This Page:
Penton, M. (2013). Tryblionella apiculata. In Diatoms of the United States. Retrieved May 24, 2016, from

Species: Tryblionella apiculata

Contributor: Marge Penton

Reviewer: Sam Rushforth


Gregory, W. (1857). On the Post-Tertiary Diatomaceous Sand of Glenshira. Part II. Transactions of the Microscopical Society of London 5:67-88, pl. I.

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.

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)

Original INA

California Academy of Sciences (CAS)

Tryblionella apiculata CAS

NCBI Genbank Taxonomy

Tryblionella apiculata NCBI

North American Diatom Ecological Database (NADED)

NADED ID: 185023

Autecology Discussion


Bill Williams River in western Arizona. The specimens presented here are from sample collected at this site.