• Category
  • Length Range
    18.0-31.5 µm
  • Width Range
    2.5-5.0 µm
  • Striae in 10 µm
    30-45
  • Reported As
    Proschkinia bulnheimii (in part) (Clavero I Oms 2009, Figs 82:4-8, 10-11, 15-18, 20-22, 25-26)

Identification

Description

Valves are lanceolate, with rounded, protracted to rostrate apices. The axial area is very narrow, with a distinct sternum. The central area is barely distinguishable. Only 2–4 nearly parallel striae on both sides of the raphe at mid-valve can be resolved with LM; other striae are not visible. Virgae are wider at mid-valve. In girdle view, valves are rectangular with rounded apices. Numerous narrow copulae are present. Frustules are weakly silicified and often fragmented during the cleaning process.

Scanning electron microscopy, external view: The valve face is covered by relatively narrow longitudinal cord-like silica strips running nearly continuously from apex to apex. Small breaks and deflections in the strips occur near mid-valve, lying noticeably above the plane of the striae. Virgae are wider in the valve middle. Proximal raphe ends are closely spaced and slightly bent toward the secondary side of the valve. The proximal raphe ends are spathulate, with raised silica rims. Terminal raphe fissures are strongly hooked toward the secondary side, extending onto the valve mantle. The opening of the fistula is not evident, but obscured by a pocket-like silica flap formed by two fused thickened longitudinal strips on the primary side of the valve.

SEM, internal view: Uniseriate striae are nearly parallel to slightly radiate in the valve middle. Striae become slightly curved and, finally, convergent near the apices, 38–43 in 10 µm. Striae are separated by raised virgae, composed of rectangular to almost square areolae, which are occluded by hymenes. Raphe branches are visible only near the central area and at the apices. The proximal raphe ends open laterally on the secondary side of the valve, within a thick axial rib. Proximal raphe ends are straight and simple. The fistula is covered by a nearly circular domed structure, located at the end of a shortened central stria close to the axial area, not reaching the axial rib. Terminal raphe ends are elongate and positioned laterally on the sternum. The raphe terminates in simple helictoglossae.

Autecology

Proschkinia browderiana has been documented in Biscayne Bay, Florida, as a seagrass epiphyte and in the hypersaline Ojo de Liebre Lagoon, Guerrero Negro, Baja California Sur, Mexico (Majewska et al. 2019).

Original Description

Frustules usually observed with partially detached valves lying in valve view, fully intact frustules rarely seen. Frustules weakly silicified, 4–6 µm wide (n = 6, natural population), rectangular in girdle view showing rounded apices and numerous narrow copulae. Valves lanceolate with rounded, protracted to rostrate apices. Valve dimensions (n = 30): length 18.0–31.5 µm, width 3–4 µm, length to width ratio 4.8–7.8. Axial area very narrow with distinct sternum. Central area barely distinguishable, showing 2–4 more distantly spaced central striae on both sides of raphe. Other striae indiscernible in LM.

Scanning electron microscopy: External view: Valve face covered by relatively narrow longitudinal cord-like silica strips running nearly continuously from apex to apex with only small breaks and deflections around the central area, lying noticeably above the plane of the striae. Near the apices, silica strips fused to form a small pore-free area. Areolae weakly visible in the grooves formed between the longitudinal strips. Virgae noticeably wider in the valve middle. Mantle shallow, lacking a clear transition between valve face and mantle. A single apically elongated slit present at the valve apices on the primary side of the valve. Raphe straight located between two thickened longitudinal strips. Strips opening near the central raphe endings. Central raphe endings very closely spaced, slightly bent towards the secondary side of the valve, spathulate with raised silica rims. Terminal raphe fissures strongly hooked towards the secondary side, extending onto the valve mantle. Fistula opening not evident, obscured by a pocket-like silica flap formed by two fused thickened longitudinal strips on the primary side of the valve.

Internal view: Uniseriate striae nearly parallel to very slightly radiate in the valve middle becoming slightly curved and finally convergent near the apices, 38–43 in 10 µm. Striae separated by clearly raised virgae, composed of rectangular to almost square areolae, occluded by hymenes, ca. 60 in 10 µm. Raphe branches visible only near the central area and at the apices, opening laterally on the secondary side of the valve within a thick axial rib. Central raphe endings straight, simple. A wafer-like silica thickening with a small blunt tip on the central nodule extending laterally towards the secondary side of the valve from the axial rib. Fistula opening covered by a nearly circular domed structure, located at the end of a shortened central stria close to the axial area, not reaching the axial rib. Terminal raphe endings elongated, lying laterally on the sternum, terminating onto simple helictoglossae. Small pore-free area present at the apices. Apices showing a slight thickening corresponding to the hooked terminal raphe fissure on the external surface of the valve with up to two small areolae at the end of the thickening. Single areola present at the apices on the primary side of the valve.

Cingulum composed of multiple open copulae, folded with the fold on the cell interior showing a row of hymenate, transapically elongated pores forming a comb-like appearance; pore density approx. 7 in 1 µm. Pars exterior plain.

  • Author
    Frankovich, Ashworth and M.J.Sullivan 2019
  • Length Range
    18.0-31.5 µm
  • Width
    3-4 µm
  • Striae in 10µm
    38-43

Original Images

Proschkinia Browderiana Orig Illus

Cite This Page

Frankovich, T. (2019). Proschkinia browderiana. In Diatoms of North America. Retrieved August 08, 2020, from https://diatoms.org/species/proschkinia-browderiana

Responses

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