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Diatoms of the United States is now known as Diatoms of North America.
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SPECIES starting with "d"


Decussata placenta

  1. Axial area narrow
  2. Proximal raphe ends prominent
  3. Areolae offset

Symmetrical biraphid - Valves elliptic with rostrate to rostrate-apiculate ends. The axial area is narrow. The raphe is filiform and straight to slightly undulate, with prominent, dilated external proximal raphe ends. Areolae are slightly offset from one another, producing decussate striae.

Denticula creticola

  1. Costae robust, parallel to curved
  2. Valve small, bacilliform
  3. Striae not visible in LM

Nitzschioid - Valves are small, with rounded ends. Striae are not visible in LM. Costae are parallel, becoming curved at the apices.

Denticula subtilis

  1. Valve small, linear-lanceolate
  2. Costae robust
  3. Ends acute

Nitzschioid - Valves are small, with acute ends. Striae of some specimens are visible in LM. Costae are mostly parallel.

Denticula tenuis

  1. Valves lanceolate to elliptic-lanceolate
  2. Protracted apices
  3. Costae distinct
  4. Raphe eccentric

Nitzschioid - Valves lanceolate to elliptic-lanceolate, with protracted apices. The raphe is distinct, positioned off center and contained within a canal. Costae are distinct and number 5-7 in 10 µm.

Diadesmis confervacea

Navicula confervacea

  1. Valves elliptic
  2. Central nodule rounded
  3. Striae punctate

Symmetrical biraphid - Valves are elliptic, with apices protracted in larger specimens. A rounded central nodule is visible when focusing on the interior of the valve. Striae are radiate, punctate and of variable length.

Diatoma ehrenbergii

Diatoma vulgaris var. ehrenbergii

  1. Valves narrow, elongate
  2. Costae 9-15 in 10 µm
  3. Apices sub-rostrate to capitate
  4. Single rimoportula present

Araphid - Valves are narrow and elongate. Apices are sub-rostrate to capitate. A single rimoportula is present near the apical pore field.

Diatoma moniliformis

Diatoma tenue var. moniliforme

  1. Smaller valves elliptic, with rounded ends
  2. Larger valves lanceolate, with subrostrate ends
  3. Valve width most often 3-5 µm
  4. Transapical ribs 6-11 in 10 µm

Araphid - Valves are elliptic to elliptic-lanceolate, with rounded to subcapitate apices. Transapical ribs are clearly visible under LM. In contrast, striae are not visible under LM.

Diatoma tenuis

Diatoma elongatum var. tenuis

  1. Valves linear with capitate ends
  2. Valves usually 3-4.5 µm wide
  3. Transapical ribs 6-11 in 10 µm

Araphid - Valves are linear with capitate apices. Transapical ribs number 6-11 in 10 µm. Striae are not distinguishable under LM. One rimoportula is positioned at one valve apex.

Diatoma vulgaris

  1. Valve elliptical to elliptical-lanceolate with rounded subrostrate ends
  2. Valve 8-12 µm wide
  3. Transapical costae 6-10 in 10 µm

Araphid - Valves elliptical to elliptical-lanceolate with broadly rounded subrostrate apices. Transapical costae visible under LM, striae not visible under LM.

Diatomella balfouriana

  1. Valves linear with rounded apices
  2. Septum present
  3. Axial area wide
  4. Proximal raphe ends distant

Symmetrical biraphid - Valves linear, with rounded apices. The axial area is wide. A septum is present extending the entire length of the valve, and has three large openings, the largest in the center, smaller two at the ends. The proximal raphe ends are relatively distant from one another; they are widely spaced.

Didymosphenia geminata

Gomphonema geminatum

  1. Valves large
  2. Headpole capitate
  3. Stigmata 2-5
  4. Apical porefield present
  5. Distal raphe deflected

Asymmetrical biraphid - The valves are large and robust. The headpole is distinctly capitate, while the footpole may be capitate or not. The number of stigmata is variable, but depends on valve size. A porefield is present at the footpole. The distal raphe is deflected at the footpole, rather than bisecting it.

Diploneis elliptica

  1. Valves elliptic
  2. Central area large, round
  3. Striae radiate
  4. Striae uniseriate

Symmetrical biraphid - Valves are elliptic. The central area is large and round. Striae are radiate throughout, becoming more strongly radiate near the apices. Striae are uniseriate. Most specimens have a single row of areolae along the longitudinal canal, but in some specimens there may be two rows of areolae.

Diploneis finnica

  1. Valves large and broadly elliptical
  2. Longitudinal canals broad
  3. Striae biseriate
  4. Central area small

Symmetrical biraphid - Diploneis finnica has large elliptical valves with biseriate striae and a small central area. The longitudinal canals are wide and lanceolate, 1/3 to 1/2 the width of the valve at the center.

Diploneis krammeri

  1. Valves elliptic to linear-elliptic
  2. Longitudinal canals narrow
  3. Striae uniseriate
  4. Central area large, orbicular

Symmetrical biraphid - Diploneis krammeri has large elliptic to linear-elliptic valves with a large orbicular central area. Striae are uniseriate and longitudinal canals are narrow.

Diploneis marginestriata

  1. Valves narrow, linear
  2. Longitudinal canals linear
  3. Central area nearly linear

Symmetrical biraphid - Valves are narrow and linear. The longitudinal canals are linear, with no inflation, or only slight inflation, at the central area. Areolae are not discernible in LM.

Diploneis ovalis

  1. Valves elliptic-oval
  2. Longitudinal canals narrow
  3. Striae uniseriate
  4. Central area large

Symmetrical biraphid - Valves are elliptic to oval and up to 33 µm wide. The longitudinal canals are narrow. Striae are uniseriate and radiate throughout. The central area is large and orbicular, up to 8.5 µm wide.

Diprora haenaensis

  1. Single row of pores along the valve margin
  2. Frustules joined into filaments
  3. Valve mantles with apical prows
  4. Open cingulum present (but missing in adjacent frustule of this image)

Araphid - Valves are linear with broad, rounded ends; the smallest valves within the size series are nearly circular. A single row of pores is present along the valve margin. Frustules are joined into filaments. The valve mantle is extended to form apical prows, a feature visible in girdle view. Under SEM, it is possible to view an open cingulum. This species is currently known only from wet walls on the island of Hawai’i.

Discostella pseudostelligera

  1. Valves extremely small
  2. Central valve flat, concave or convex
  3. Central ornamentation present or absent
  4. Marginal fultoportulae evident
  5. Fultoportulae may possess projecting tubes and/or hoods

Centric - Valves are extremely small, less than 10 µm in diameter. The central valve may be flat, concave or convex. Ornamentation in the central valve may be absent, or there may be a stellate ornamentation. Marginal fultoportulae are evident in LM. These fultoportulae may possess externally projecting tubes and/or hoods.

Discostella stelligera

  1. Valves concave or convex
  2. Central stellate pattern of striae
  3. Marginal striae form well-defined ring

Centric - Valves are either concave or convex in the center. Central striae form a stellate pattern, although the central striae may be absent or composed of ghost striae.The marginal striae are of equal length.

Distrionella incognita

  1. Valves linear with capitate ends
  2. Valves < 3 µm wide
  3. Costae 11-17 in 10 µm
  4. Striae 20-26 in 10 µm

Araphid - Valves linear with capitate ends and less than 3 µm wide. Costae number 11-17 in 10 µm. Striae number 20-26 in 10 µm.