Valves are heteropolar, with a rounded headpole and cuneate footpole. Frustules may have a slight torsion about the apical axis. Length to width ratio is 3-4:1. A narrow-lanceolate hyaline axial area is present in the center of the valve, along the apical axis. Porcae, or transapical undulations, are usually positioned opposite each other, on either side of the apical axis. There are transapical depressions between porcae along the apical axis from headpole to footpole, forming a distinct corrugated pattern. Porcae are radiate at the apices. An alar wing is evident in girdle view. The raphe is placed in a raised canal and the canal appears about as wide as the fenestrae, which number 18-26 in 100 μm. The raphe is situated atop a raised keel, or alar wing, around the valve margin. Alar canals are visible as hollow openings associated with the porcae along the margin between the valve face and the advalvar side of the raphe system.
This taxon was observed in Waller Creek, a small stream in an urban area of Austin, Texas. It was unattached and fairly abundant in the benthos. It was also reported from Alaska, where it tended to be present in alkaline environments (Foged 1981). That publication also described the species as having a global distribution distribution and as being oligohalobous (Foged 1981). Oligohalobous taxa include those that prefer slightly brackish waters, as well as taxa that prefer freshwater environments but can tolerate brackish waters (Pienitz et al. 1991).
The following are examples of reports of this taxon included in a species list - but lacking verifiable images. This taxon was reported in oligotrophic lakes with acidic conditions in Florida (Whitmore 1989). Hemphill-Haley (1990) reported (as Surirella tenera) in middle intertidal samples of Niawiakum River in northern Willapa Bay, Washington. Also, Ognjanova-Rumenova et al. (2011) reported the greatest relative abundance of this taxon in Bliznaka, Bubreka, Okoto (Sedemte Ez- era Cirque) and Dolno Marichino, Gorno Marichi-no (Marishki cirque) lakes, the alkaline cirques of the Rila Mountains of southwest Bulgaria.
From 2/9/2016 until 6/30/2024, this taxon appeared as Surirella tenera W.Greg. Following the nomenclatural transfers of Ruck et al. (2016), the webpage was updated to Iconella tenera (W.Greg.) Ruck and Nakov 2016. - S. Spaulding
Rouzbahani, T. (2016). Iconella tenera. In Diatoms of North America. Retrieved September 07, 2024, from https://diatoms.org/species/iconella_tenera
The 15 response plots show an environmental variable (x axis) against the relative abundance (y axis) of Iconella tenera 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.