• Category
  • Length Range
    7–22.5 µm
  • Width Range
    5–7 µm
  • Striae in 10 µm
    9–11

Identification

Description

Valves with rostrate to cuneate ends, or broadly rounded in smaller specimens. The central area is expanded laterally. The valve face is undulate due to raised costae. The valve face/mantle junction forms a sharp angle. The abvalvar edge of the mantle is parallel to the valve face/mantle junction. In girdle view, frustules are rectangular with raised central area. Cells form short ribbon-like colonies, joined by linking spines. The axial area is narrowly lanceolate. Striae are distinct, composed of up to four rows of round areolae, which converge into a single row at the axial area and valve mantle. Striae terminate sharply at axial area. Striae extend continuously from valve face to mantle. Costae are wider than the striae. Spines are spatulate and sometimes expose laminar ligulae projected downwards to the valve mantle. Spines are present along the valve face edge, except at the apices, and are located on the striae. Small, ocellulimbus type, apical pore fields with round poroids are present on both valve apices, but are more developed at foot pole than at the head pole. Pore fields are located on the junction between the valve face and mantle. Rimoportulae are absent. Copulae, or girdle bands, are open and not perforated. Valvocopulum (first girdle band) is wider than the rest of the girdle elements and presents well-developed fimbriae.

Autecology

Significant populations of P. mimetica were found in alkaline water (pH = 8.2) of moderately low conductivity (179 mS/cm) and moderate concentrations of P (orthophosphate) and total N (0.129 mg/L and 0.437 mg/L, respectively).

Original Description

Frustula aspectu cingulari rectangularia in catenis cum marginibus spiniferis. Valvae heteropolares cruciform-rhomboid, extremiis acuminat-subrostratis. Longitudo 7–22 mm, latitudo 5–7 mm, striae 9–11 per 10 mm (n = 50). Sternum linearum vel lanceolatum. Striae parallelae aut aliqua tulus radiatae. Areolae compositio multiposthoc singulari ordinis. Volae nullae. Costae elevare crassae cum spinae bifurcate, areae porellum ad apices distincta. Valvocopulae maior quam alias elementa.

  • Author
    E.Morales 2005
  • Length Range
    7-22 µm
  • Width
    5-7 µm
  • Striae in 10µm
    9-11

Original Images

P Mimetica Orig Illus 1
P Mimetica Orig Illus2 1
P Mimetica Orig Des 1

Cite This Page

Morales, E, and Rosen, B, and Spaulding, S. (2013). Punctastriata mimetica. In Diatoms of North America. Retrieved July 21, 2018, from https://diatoms.org/species/punctastriata_mimetica

Responses

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