• Category
  • Length Range
    12-25 µm
  • Width Range
    5.4-7.0 µm
  • Striae in 10 µm
    12-15

Identification

Description

Valves are lanceolate with capitate to subrostrate apices. Raphe valve has a linear axial area and a variable central area - from transversely rectangular to elliptical. Rapheless valve has a linear-lanceolate axial area and an asymmetrical central area containing a hood on the internal valve surface. The raphe is straight with expanded external proximal endings. Terminal raphe fissures are curved to the secondary side of the valve. The striae are multiseriate, radiate throughout both valves.

Note that in the type population larger valves have only capitate apices. Populations from other locations have large valves (large valves are early stages in the vegetative life cycle) with subrostrate valve apices. These two morphologies are included here in the concept of Planothidium biporomum, but further studies may show that they represent separate species.

Autecology

Original Description

Valve lanceolate, ends subcapitate; length 20.8-22.8 μ, width 6.8-7.0 μ; striae straight, finely punctate, radiate throughout 14-16/10 μ; raphe valve: axial area narrow linear-lanceolate, central area moderate, transapically rectangular; raphe thin, sigmoid at terminal pores; rapheless valve: pseudoraphe narrowly linear lanceolate; unilateral horse-shoeshaped silaceous thickening superimposed on broad semicircular thickening. This taxon resembles several varieties of Achnanthes lanceolata (Bréb.) Grun. (K. sv. Vet-Akad. Handl. 17(2): 23, 1880) particularly A. lanceolata var. haynaldi (Saarsch.) Cl. (Diatomiste 2(17): 99, pl. 7, fig. 14, 1894). It differs in that the axial area of the raphe valve is distinctly lanceolate rather than linear and the terminal raphe pores are sigmoid, whereas in A. lanceolata var. haynaldii they are unilaterally bent. The rapheless valve differs from that of A. lanceolata var. haynaldii in that the pseudoraphe is lanceolate and the unilateral siliceous platform is composed of two overlapping areas of different thickness rather than a single platform.

  • Basionym
    Achnanthes biporoma
  • Author
    M.H.Hohn and Hellerman 1963
  • Length Range
    20-8-22.8 µm
  • Width
    6.8-7.0 µm
  • Striae in 10µm
    14-16

Original Images

Orig Ill  Plbip
Orig Descr  Lbip

EMAP Assessment

EMAP Distribution

Planothidium Biporomum 40 Copy
Map 40

Response Plots

Planothidium Biproromum Copy

Cite This Page

Potapova, M. (2010). Planothidium biporomum. In Diatoms of North America. Retrieved June 18, 2018, from https://diatoms.org/species/planothidium_biporomum

Responses

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