• Category
  • Length Range
    29-37 µm
  • Width Range
    8.0-9.5 µm
  • Striae in 10 µm
    14-15 on raphe valve, 12-13 on rapheless valve

Identification

Description

Valves are triundulate, with broadly rounded ends. The raphe valve has a narrow axial area and a nearly rectangular central area extending to the valve margins. The raphe is externally sinuous, with proximal ends deflected slightly in one direction and distal ends curved strongly towards mantle in the opposite direction. The rapheless valve has an axial area near the valve margin. Striae are punctate and radiate throughout on the raphe valve. On the rapheless valve, the striae are parallel in the center, becoming radiate with respect to the axial area then becoming slightly to strongly curved at the ends.

Autecology

Achnanthes undulorostrata was described from the island of Maui, Hawaii. It was also found in collections from Oahu. This taxon occurs in relatively dry sites in association with A. tumescens, Pinnularia borealis, Diadesmis spp. and Cosmioneis spp.

Original Description

Valves triundulate with broadly rounded ends, 30.5-35.5 µm long, 8.0-9.5 µm wide. Raphe valve with narrow axial area and a nearly rectangular central area extending to the valve margins. Raphe externally sinuous, with proximal ends deflected slightly in one direction, with distal ends curved strongly towards mantle in opposite direction (Fig. 63). Internal raphe slits with proximal ends slightly deflected to one side (Fig. 64). Rapheless valve with axial area near valve margin. Striae punctate, radiate throughout on raphe valve (Figs 55¬-58), on rapheless valve parallel in the center, becoming radiate with respect to the axial area, slightly to strongly curved at the ends (Figs 59-62, 65-66), 14-15 in 10 µm on raphe valve, 12-13 in 10 µm on rapheless valve. Intemal costae separating striae, wíth oblique ridges in rapheless valve resulting in a spiral pattern visible in SEM (Fig. 66). Puncta 16 in 10 µm on both valves.

  • Author
    R.L.Lowe and A.R.Sherwood 2009
  • Length Range
    30.5-35.5 µm
  • Width
    8.0-9.5 µm
  • Striae in 10µm
    14-15 in 10 µm on raphe valve, 12-13 in 10 µm on rapheless valve

Original Images

Achnanthes undulorostrata orig illus
Achnanthes undulorostrata orig descr

Cite This Page

Lowe, R. (2011). Achnanthes undulorostrata. In Diatoms of North America. Retrieved July 21, 2018, from https://diatoms.org/species/achnanthes_undulorostrata

Responses

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