• Category
  • Length Range
    21-93 µm
  • Width Range
    4.5-6.6 µm
  • Striae in 10 µm
    11-14 in the valve center, 16-18 near the valve apices.

Identification

Description

Valves with the ventral margin slightly concave to nearly straight, the dorsal margin evenly convex up to the rounded ends, with apices slightly set off by a change in slope of the dorsal margin, 21 – 93 μm long, 4.5 – 6.6 μm wide. Helictoglossae prominently visible in the light microscope as apical thickenings. Raphe extending from helictoglossa to 20-30% of the length of the valve. Striae slightly radiate, radiate at apices, 11 – 14 in 10 μm in the valve center, 16 – 18 in 10 μm near the valve apices. Rimoportula apical, at one end of valve, nearly parallel to striae.

In valve outline, it is most similar to E. minor, and bears particularly a close similarity to a valve out of the Taunus Mountains in Germany (Krammer & Lange-Bertalot 1991, Tafel 142, Fig. 15) attributed to E. minor. Although this previously figured valve may be conspecific with E. macroglossa, the size range of specimens from the type locality includes valves of much greater length than reported for E. minor, and the ends are not nearly as attenuated as in that taxon (Krammer & Lange-Bertalot 1991, Tafel 142, Figs 7-9, 13, 14). Eunotia macroglossa keyed to E. soleirolii based on the European flora (Krammer & Lange-Bertalot 2000); however it differed markedly in overall valve shape. Similarly, E. macroglossa did not fit the description for E. pectinalis with which E. soleirolii is sometimes confused. Eunotia soleirolii and E. pectinalis have parallel edges that end in a slight shoulder at the valve edge (Krammer & Lange-Bertalot 1991), in contrast with E. macroglossa which had a slightly curved dorsal edge, with the valve ends only very slightly set off from the evenly curved dorsal margin. The helictoglossae of E. macroglossa appeared further from the apices than its position in both E. soleirolii and E. pectinalis. Additionally, SEM micrographs of E. soleirolii show spines on the valve apices at the junction of the valve face and mantle, which were absent from E. macroglossa. Other distinguishing features of this taxon include the radiate striae at the valve apices. These are clearly visible even in most LM views (if ends are focused for this feature), and are visible in external SEM’s of all valves. The external pore of the rimoportula is inconspicuous in comparison to many taxa. The mantle has a large hyaline area associated with the raphe as it curves from the mantle up on to the valve face. The raphe end on the valve face is usually simply curved, but can have a more irregular structure.

Autecology

Epiphytic on bryophytes; found in low abundance in streams around the Great Smoky Mountains National Park, occasionally observed in higher abundances in mid to high elevation springs and headwater streams ranging from 1300 to 1600 m altitude.

Gsm 8 10 05 8  F 0103
Credit: P.C. Furey
Type location: Otter Creek, Great Smoky Mountains National Park, Cocke County, Tennessee

Original Description

Similar to E. minor (Kütz.) Rabh., E. pectinalis (Dillwyn) Rabh. and E. soleirolii Kütz. (Rabh.), but notable for the prominent helictoglossae and minor differences in valve outline. Valves with the ventral margin slightly concave to nearly straight, the dorsal margin evenly convex up to the rounded ends, with apices slightly set off by a change in slope of the dorsal margin, 21 – 93 μm long, 4.5 – 6.6 μm wide. Helictoglossae prominently visible in the light microscope (LM) as apical thickenings. Raphe extending from helictoglossa to 20-30% of the length of the valve. Striae slightly radiate, radiate at apices, 11 – 14 in 10 μm in the valve center, 16 – 18 in 10 μm near the valve apices. Rimoportula apical, at one end of valve, nearly parallel to striae.

  • Author
    Furey, Lowe, and Johansen 2009
  • Length Range
    21-93 µm
  • Width
    4.5-6.6 µm
  • Striae in 10µm
    11-14 in the center valve, 16-18 at the ends

Original Images

Eunotia macroglossa orig illus
Eunotia macroglossa SEM
E Macroglossa  Cropof Orig Pdf
Original text and images reproduced with permission by the author.

Cite This Page

Furey, P. (2011). Eunotia macroglossa. In Diatoms of North America. Retrieved July 17, 2018, from https://diatoms.org/species/eunotia_macroglossa

Responses

The 15 response plots show an environmental variable (x axis) against the relative abundance (y axis) of Eunotia macroglossa 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.