• Category
  • Length Range
    15-32 µm
  • Width Range
    11-23 µm
  • Striae in 10 µm
  • Synonyms
    Cocconeis binotata Grunow 1863
    Orthoneis binotata (Grunow) Grunow 1867



Valves are broadly elliptic, such that the valve length is almost twice the width. Striae are composed of punctate areolae arranged in a crossed, nearly decussate, pattern. Striae become radiate near the apices. The raphe is straight, terminating a short distance from the valve margin at the apices. The proximal raphe ends are rounded. The central area is small and transversely elongated into a narrow, lanceolate fascia that terminates before reaching the valve margin. A single, rectangular partectum is present at the middle of each side of the valvocopula. The inner margins of the partectae are smooth and straight. Careful focusing on the plane of the partectal ring in LM reveals the external opening of the partectal pore in the middle of each partectum along the outer margin.

SEM micrographs of valve internal and external ultrastructure including the valvocopula and partecta are available (Ricard 1975, Stephens and Gibson 1979, Lobban et al. 2012, Pennesi et al. 2013, Álvarez-Blanco and Blanco 2014). An SEM of the external partectal pore is available in Figure 7 of Pennesi et al. (2013).


The specimens shown on this page were sampled from seagrass (Syringodium filiforme and Thalassia testudinum) and an unknown ascidian found along the beach shoreline of St. George Island State Park, Franklin County, Florida. It co-occurred with numerous other Mastogloia species, including very abundant M. pusilla, many species of Amphora, a few species of Epithemia, and a diverse community of epiphytic diatoms.

In live samples, epiphytic and free-living live cells were observed. Most cells were moving along the seagrass surface. On Syringodium, hydrozoan epibionts were observed with epizooic M. binotata and numerous individuals of Cocconeis spp. Hein et al. (2008) observed M. binotata attached to various seagrass, periphyton, zooplankton, snails, and sand. It has a reported pantropical distribution: Indian River, Florida (epiphytic on Halodule wrightii seagrass, Stephens and Gibson 1979), Puerto Rico (Navarro 1983), Guam (Lobban et al. 2012), the Bahamas (Hein et al. 2008), and Calabria, Italy (Pennesi et al. 2013).

The dominant species within epiphyte communities of diverse Mastogloia genera on seagrass may depend upon the types and shapes of seagrass blades. More observations are needed of live specimens of Mastogloia spp. to understand their preference for attachment to the surfaces of associated flora.

Saint George Island FL
Credit: Sylvia Lee
Beach shoreline with seagrass on St. George Island State Park, Florida
Autecology seagrass and ascidian Mastogloia
Credit: Sylvia Lee
Seagrass with numerous epibionts and unknown ascidian

Original Description

Cocconeis valvis ovatis, utroque latere macula semicirculari marginali notatis, punctis in lineas decussatas et transversales subradiantes ordinatis, 36-42 in 0.001". Longit. 0.0008-0.0017", latitudo valvae 0.0005-0.0010".
- Tab. nostr. 13 fig. 13 a (400/1)
Habitat in maribus Europam alluentibus nec non in mari rubro.

  • Basionym
    Cocconeis binotata
  • Author
    Grunow 1863

Original Images

Cocconeis binotata Grunow 1863 orig image
Cocconeis binotata Grunow 1863

Citations & Links



Cite This Page

Gilpin, C., Lee, S. (2023). Mastogloia binotata. In Diatoms of North America. Retrieved October 03, 2023, from https://diatoms.org/species/mastogloia-binotata


The 15 response plots show an environmental variable (x axis) against the relative abundance (y axis) of Mastogloia binotata from all the stream reaches where it was present. Note that the relative abundance scale is the same on each plot. Explanation of each environmental variable and units are as follows:

ELEVATION = stream reach elevation (meters)
STRAHLER = distribution plot of the Strahler Stream Order
SLOPE = stream reach gradient (degrees)
W1_HALL = an index that is a measure of streamside (riparian) human activity that ranges from 0 - 10, with a value of 0 indicating of minimal disturbance to a value of 10 indicating severe disturbance.
PHSTVL = pH measured in a sealed syringe sample (pH units)
log_COND = log concentration of specific conductivity (µS/cm)
log_PTL = log concentration of total phosphorus (µg/L)
log_NO3 = log concentration of nitrate (µeq/L)
log_DOC = log concentration of dissolved organic carbon (mg/L)
log_SIO2 = log concentration of silicon (mg/L)
log_NA = log concentration of sodium (µeq/L)
log_HCO3 = log concentration of the bicarbonate ion (µeq/L)
EMBED = percent of the stream substrate that is embedded by sand and fine sediment
log_TURBIDITY = log of turbidity, a measure of cloudiness of water, in nephelometric turbidity units (NTU).
DISTOT = an index of total human disturbance in the watershed that ranges from 1 - 100, with a value of 0 indicating of minimal disturbance to a value of 100 indicating severe disturbance.