• Category
  • Length Range
    9-25 µm
  • Width Range
    4.8-7.0 µm
  • Striae in 10 µm
  • Synonyms
    Planothidium lanceolatum var. haynaldii (Schaarschmidt) Bukht.
    Achnanthes lanceolata var. haynaldii (Schaarschmidt) Cleve



Valves are lanceolate to elliptical-lanceolate with capitate apices; specimens at the small end of the size range are nearly elliptical. The raphe valve has a linear axial area and central area that varies in shape - from transversely rectangular to elliptical. The rapheless valve has a linear-lanceolate axial area that slightly widens in the center. The asymmetrical central area on the rapheless valve contains a rimmed depression on the internal valve surface.The raphe is straight with expanded external proximal endings. Terminal raphe fissures are curved to the secondary valve side. The striae are multiseriate and radiate throughout both valves.

This page follows the concept presented in Patrick and Reimer (1966). However, recent investigation of the type material Achnanthes haynaldii (Wetzel et al. 2014) shows that that this taxon page requires revision.


Original Description

A. minuta, solitaria vel 2-3 in fascias conjuncta, lateribus anguste linearibus, leniter genuflexis; valvis oblongo-ellipticis apicibus rotundatis, vel elliptico-lanceolatis sub polis leniter constrictis, medio inflatis, - vel cymbiformibus, medio valde tumidis, ventricosis, utroque fine porrectis, apicibus obsolete capitatis, rotundatis; nodulo centrali valvae inferioris lateraliter dilatato duam fasciam semitransversalem Vformem referent, linea media recta, striis transversis subradiantibus distinctis, subtilibus circa 140 in 100 μ.

  • Basionym
    Achnanthes haynaldii
  • Author
    Schaarschmidt 1881
  • Striae in 10µm

Original Images

Achnanthes haynaldii orig descr

EMAP Assessment

EMAP Distribution

Planothidium Haynaldii   Schaarschmidt   Lange  Bertalot 10
Map 10

Response Plots

Planothidium Haynaldii   Schaarschmidt   Lange  Bertalot

Cite This Page

Potapova, M. (2011). Planothidium haynaldii. In Diatoms of North America. Retrieved February 24, 2020, from https://diatoms.org/species/planothidium_haynaldii


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