Fragilaria pennsylvanica | Species - Diatoms of North America

Category

Araphid
Length Range

12.8-25.6 µm
Width Range

1.8-2.2 µm
Striae in 10 µm

19.2-21.6

Contributor

Gina LaLiberte - Nov 2015
Reviewer

Eduardo A. Morales - Dec 2015

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Identification

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Description

Valves are small, narrow and linear to linear-lanceolate, tapering to narrow rostrate apices. The axial area is broadly lanceolate. Striae are short, marginal, alternating and slightly radiate. The central area is variable, with striae slightly shortened on one side and absent on one side, or absent on both sides. The absence of striae makes the central area appear hyaline when viewed with the light microscope, but when enlarged and enhanced in photographs the central area may appear to have ghost striae.

Autecology

Morales (2003) noted that Fragilaria pennsylvanica likely forms sessile stellate colonies. The Pennsylvania streams in which it has been found so far are non-calcareous and have relatively warm temperatures (21-27°C) during the growing season (Morales 2003).

Size Range, µm3

11-100
Motility

Non-motile
Attachment

Prostrate
Habitat

Benthic
Waterbody

Inland
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Original Description

Length: 12–24.5 μm, width: 1–2.5 μm, striae: 18–22 per 10 μm. Central area clear on one or both sides (Figs. 20, 22). Central sternum wide and lanceolate (Figs. 20–26). Striae alternate and short, composed of round to slightly apically elongated areolae. Up to four areolae located on valve face and up to two on the valve mantle per stria. Volae were not observed. Spines absent. Apical pore fields of the ocellulimbus type with three to four rows of vertical poroids (Figs. 25–26). One rimoportula present (Figs. 24, 25). Girdle bands closed apparently bearing small isolated unoccluded perforations (Figs. 27–29). Plastids unknown.

Author

E.Morales 2003
Length Range

12-24.5 µm
Width

1-2.5 µm
Striae in 10µm

18-22

Original Images

Fragilaria Pennsylvanica Morales Originaldescription

Citations & Links

Citations

Morales, E.A. (2003) Fragilaria pennsylvanica, a new diatom (Bacillariophyceae) species from North America, with comments on the taxonomy of the genus Synedra Ehrenberg Proceedings of the Academy of Natural Sciences of Philadelphia 153: 155-166.

Cite This Page

LaLiberte, G. (2015). Fragilaria pennsylvanica. In Diatoms of North America. Retrieved December 16, 2024, from https://diatoms.org/species/50952/fragilaria_pennsylvanica

Responses

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