• Category
  • Length Range
    12-20 µm
  • Width Range
    4.7-7.5 µm
  • Striae in 10 µm
  • Reported As
    Achnanthes delicatula (Cleve and Grunow 1880)



Valves are lanceolate with protracted subrostrate apices The raphe valve has a transversely elliptical or rectangular central area. The rapheless valve has a linear-lanceolate axial area. The features of the middle of the rapheless valve are variable across populations: valves may lack a distinguishable central area, or two middle striae on one side of the axial area can be slightly more distant from one another than from the other striae. The raphe is straight with expanded external proximal ends. The striae are strongly radiate on the raphe valve and slightly radiate on the rapheless valve.

Note that this concept of P. delicatulum more or less corresponds to the "Sippen mit schnabelartig vorgezogenen Polen" (Krammer and Lange-Bertalot 1991, Figs 39:6-14), while the neotype of Achnanthes delicatula may represent a similar, but different species (Figs 39: 1-5. Further work is needed to clarify taxonomy of this species complex.


Original Description

A. a latere secundario ven-tricosum, apicibus productis.

  • Basionym
    Achnanthidium delicatulum
  • Author
    Kütz. 1844
  • Length Range
    16 µm

Original Images

Orig Ill  Pldel
Orig Descr  Pldel

Cite This Page

Potapova, M. (2010). Planothidium delicatulum. In Diatoms of North America. Retrieved May 18, 2024, from https://diatoms.org/species/planothidium_delicatulum


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