Identification

Description

Valves are elliptic. Striae are 23-26 in 10 µm, and may be greater in some valves. Areolae are 28-33 in 10 μm. The axial area is narrow and linear, broadening slightly towards the central area; the central area is round to elliptic. The raphe is filiform with expanded central fissures. The terminal raphe fissures are small on the valve face. The striae are strongly radiate, and are usually visibly punctate. Long and short striae alternate in the central area. Short striae are present extending just inside the margin of the valve face, and continuing onto the mantle. The stria density increases towards the apices. Areolae are elliptic, with depressed occlusions, and with a row of elongated areolae along the axial area that lengthen to slit-like structures around the central area. At each apex one enlarged pore-like fissure is visible immediately adjacent to the distal fissures on the primary side of the valve; this pore is elliptical on the external surface and transapically elongated on the internal surface. Internally, the raphe is linear, terminating in a small helictoglossa at the terminal fissure. Helictoglossa not present at proximal fissure. Internally, the striae are positioned between costa thickenings, and each stria is covered internally by a hymen. Valves have two or more open copulae, with one row of pores.

Navicula pseudoscutiformis was identified from the Gulf of Finland (Snoeijs and Potapova, 1995, p. 32). The specimens are similar to C. vincentii in valve shape and features, however the specimens differ from C. vincentii by a lanceolate axial area and the absence of enlarged, pore-like structures at the apices. A specimen identified as N. pseudoscutiformis (Krammer and Lange-Bertalot,1986, fig. 59: 12) is also similar to C. vincentii, however it is difficult to discern the length of the areolae around the central area. Closer examination of specimens identified as C. pseudoscutiformis may reveal their affinity to C. vincentii.

Autecology

The type locality of C. vincentii is a shallow arctic pond (max. depth 1 m) near Alert (White Pond, Ellesmere Island, Nunavut, Canada) with extremely inorganic, sandy sediment. Water chemistry of the pond was: pH 8.3, specific conductivity 185 μS, total phosphorus 8.7 μg/L, total nitrogen 0.562 mg/L, dissolved organic carbon 1.9 mg/L and dissolved inorganic carbon 28.0 mg/L.

Original Description

Valvae ellipticae cum anguste rotundatis extremis. Longitudo 12-15 μm, latitudo 8-11 μm, cum 23-26 (30?) striis et 28-33 areolis in 10 μm. Axialis area angusta, linearis, dilatans leviter ad centralem aream; centralis area rotunda ad ellipticam. Raphe filiformis cum expansis centralibus fissuris. Terminalis raphis fissurae parvae super fronde. Striae valenter radiatae, fere manifesto punctatae. Longae et breves striae alternate in centralis area. Breves striae praesentes extensae modo internam marginem frondis, et continuantes deorsum limbum. Striae crassitudines crescentes versus apices. Areolae ellipticae, cum series elongatae areolae secus area axialem quam elongatam ad pseudorimas structuras circa centralem aream. Areolae cum depressis occlusis. Ad uterque apex unus ampliatus porus praesens statim adiacet distales fissures in primo latere valvae; porus ellipticus in externa pagina et transapicallis elongatus in interna pagina. Interne, raphe linearis, in parva helictoglossa ad terminalem fissuram. Helictoglossa non praesentia ad proximalem fissuram. Interne, striae positae inter costas concreties, unaquaeque stria tecta ab hymenio. Valvae cum dua vel pluris apertis copulis cum una series pori.

  • Author
    Antoniades & Hamilton in Antoniades et al. 2009
  • Length Range
    12-15 µm
  • Width
    8-11 µm
  • Striae in 10µm
    23-26

Cite This Page

Hamilton, P. (2011). Cavinula vincentii. In Diatoms of North America. Retrieved July 22, 2018, from https://diatoms.org/species/cavinula_vincentii

Responses

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