Mastogloia pseudosmithii

Lee, E.E.Gaiser, Van de Vijver, Edlund, and S.A.Spauld. 2014      Category: Symmetrical biraphid

REPORTED AS: Mastogloia smithii Morphotype II (Slate and Stevenson 2007) 

Mastogloia lacustris


Mastogloia pumila

LM scalebar = 10 µm = 80 pixels.


Contributor: Sylvia Lee - January 2014
Length Range: 28-51 µm
Width Range: 11-14 µm
Striae in 10 µm: 16-17


Valves are elliptic-lanceolate with rostrate ends (small valves have subrostrate to round ends). Striae are punctate, gently radiate and become parallel at the apices. The striation pattern on the valve face continues unchanged onto the mantle. The central area is elliptic to polygonal, and is often asymmetric. Areolae are round to elliptic, 16 areolae per 10 µm, and some are reduced around the central area. The areolae are internally occluded by a cribrum. The raphe is straight with a median kink. The proximal raphe ends are expanded and pore-like and open into a spathulate groove. The distal raphe ends extend centrally over the mantle and hook to the same side. There is a small hyaline area where the curve of the distal raphe ends occurs.

Internally, the raphe is straight and encased in a thickened sternum. The internal proximal raphe ends are straight and the sternum fuses into the thickened central nodule. The internal distal raphe ends are occluded by pseudosepta. The partectal ring is closed, forming a complete band, and lacks a flange separating the ring from the valve margins. The partectal ring has a broad cleft at both apices. Pores are present between partecta near the advalvar edge of the partectal ring. Partecta are distributed along both sides of the partectal ring except near the apices. Partecta are clearly distinguishable and evenly sized, but are slightly larger closest to the apices, 6-8 partecta in 10 µm. The virgae and vimines are the same thickness throughout the valve interior. Cribral pores become irregular near the sternum and the central nodule.

Mastogloia pseudosmithii, M. calcarea, M. lacustris and M. albertii have all been misidentified as M. smithii, which has not yet been verified in North America. Mastogloia pseudosmithii and M. calcarea have not been verified outside of the Florida Everglades, the Caribbean and Mexico.

Cite This Page:
Lee, S. (2014). Mastogloia pseudosmithii. In Diatoms of the United States. Retrieved April 25, 2018, from

Species: Mastogloia pseudosmithii

Contributor: Sylvia Lee

Reviewer: Sarah Spaulding


Gaiser, E., La Hée J.M., Tobias, F.A.C. and Wachnicka, A.H. (2010). Mastogloia smithii var lacustris Grun.: a structural engineer of calcareous mats in karstic subtropical wetlands. Proceedings of the Academy of Natural Sciences of Philadelphia 160(1):99-112. 10.1635/053.160.0111

Lee S.S., Gaiser E.E., Van de Vijver, B., Edlund, M.B., and Spaulding, S.A. (2014). Morphology and typification of Mastogloia smithii and M. lacustris, with descriptions of two new species from the Florida Everglades and the Caribbean region. Diatom Research. doi:10.1080/0269249X.2014.889038

Slate, J.E. and Stevenson, R.J. (2007). The diatom flora of phosphorus-enriched and unenriched sites in an Everglades marsh. Diatom Research 22: 355–386. 10.1080/0269249X.2007.9705721

Links & ID's

Index Nominum Algarum (INA)

Original INA

California Academy of Sciences (CAS)

North American Diatom Ecological Database (NADED)


Autecology Discussion

Comprises <1% of total diatom abundance in non-calcareous periphyton assemblages in waters of high conductivity, such as brackish areas near the coastal marshes of the Everglades, slightly acidic pH, and slightly higher periphyton total phosphorus. Weighted-averaging optima: water depth 41 cm, pH 6.7, conductivity 2500 µS/cm, and periphyton total phosphorus 480 μg/g.