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A Diatom - Gomphadelpha montana
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General Description
Morphological Category – Asymmetric biraphid
Valves lanceolate with acutely pointed headpoles. Footpole capitate and separated from the valve body by a very narrow isthmus.
Axial Area very narrow, barely wider than the raphe, and merges with a small rhombic central area.
Central Area contains a single stigma on one side of the central nodule.
Raphe distinctly lateral and somewhat sinuous. External proximal raphe ends narrow and bent towards the stigma. Terminal raphe ends are comma-shaped. From the central area towards the headpole,
striae are markedly radiate and sinuous, becoming parallel and straight close to the headpole. From the central area towards the footpole, striae are straight and slightly radiate. A longitudinal line interrupts the striae close to and on either side of the axial area.
Size Range Length 34–58 µm.
Width 10.6–13.4 µm.
Stria e in 10mm 13–15 at valve center; 15–16 at the apices.
Stigmata 1.
Useful Link :
Diatom Glossary [Diatoms of North America website]
Diagnostic Characteristics
Smaller than
Gomphadelpha septa with narrower ends and a narrower isthmus between valve body and footpole
Range Comments
Recorded from three locations in Montana: Flathead Lake, Hebgen Lake and Black Coulee NWR.Type Locality
Habitat
Lakes, reservoirs and wetlands.
Ecology
Cool, alkaline waters with moderate nutrients and conductivity.Water Chemistry
Reproductive Characteristics
Diatoms typically reproduce by cell division (mitosis) and occasionally by meiosis—sexual reproduction in which female and male gametes combine to form a specialized zygote called an auxospore. Repeated divisions result in cells of a population becoming progressively smaller and smaller. When cells reach a critically small size, sexual reproduction is initiated, resulting in an auxospore and initial cells that are the largest attainable for the species, after which cell division and size reduction resume (Amato 2010).
Stewardship Responsibility
Threats or Limiting Factors
Climate change and regional warming.
References
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