SPECIES starting with "e"

 

Ellerbeckia arenaria

  1. Frustules robust and drum-shaped
  2. Frustules joined in colonies
  3. Ridges and grooves on linking valves extend to valve margin

Centric - Ellerbeckia arenaria has robust, drum-shaped frustules that are linked by their valve faces to form long filamentous colonies. The interlocking ridges and grooves on linking valves extend to the valve margin.


Encyonema hamsherae

  1. Apices slightly capitate
  2. Raphe straight
  3. Striae radiate in center, parallel at apices

Asymmetrical biraphid - The dorsal margin is arched, while the ventral margin is slightly convex to somewhat flat in smaller specimens. Apices are protracted and slightly capitate. Striae are radiate in the center valve, becoming nearly parallel at the apices. Central striae on the ventral side are often somewhat bowed. The dorsal stria density is usually greater than the ventral stria density by 1 or 2 in 10 µm.


Encyonema hebridicum

Cymbella hebridica

  1. Ventral margin tumid at center
  2. Central area round to indistinct

Asymmetrical biraphid - The ventral margin is usually moderately tumid in the center valve, while the ventral margin in the smallest specimens is convex. The central area varies within populations, from round to indistinct.


Encyonema latum

  1. Ventral margin very slightly expanded
  2. Valve apicies rounded
  3. Central, dorsal striae 6-8 in 10 µm
  4. Dorsal areolae closest to the central area oval, becoming lineolate

Asymmetrical biraphid - The species was described from the Miocene lacustrine diatomites of Terrebonne, Oregon (Krammer 1997). Valves are strongly dorsi-ventral. The dorsal margin is broadly arched, while the ventral margin is only very slightly expanded. The valve apices are rounded. The axial area is relatively broad in the central part, narrowing at the valve ends.


Encyonema nicafei

  1. Ventral margin linear
  2. Valve apicies broadly rounded
  3. Central dorsal striae number 9 in 10 μm
  4. Rows of dorsal areolae closest to the central area oval, becoming lineolate

Asymmetrical biraphid - Valves are strongly dorsi-ventral. The dorsal margin is broadly arched, while the ventral margin is linear with broadly rounded apices.


Encyonema norvegicum

Encyonema norvegica

  1. Valves relatively narrow
  2. Central area asymmetric

Asymmetrical biraphid - Valves are relatively narrow. The central area is asymmetric and slightly to moderately rounded on the dorsal side. The ventral margin is variable in shape and may be slightly biundulate or triundulate.


Encyonema reimeri

  1. Ventral margin expanded
  2. Valve terminations acute
  3. Central, dorsal striae count measures 10 in 10 µm
  4. Rows of dorsal areolae closest to the central area oval, becoming lineolate

Asymmetrical biraphid - Valves are strongly dorsi-ventral. The dorsal margin is broadly arched, while the ventral margin is expanded with acute valve apices. The number of dorsal, central striae is important in distinguishing this species from similar species, as well as the density of areolae in a central, dorsal striae. Ventrally, central striae number 8 in 10 μm, and distal striae number 6 in 5 μm. The density of areolae within a central, dorsal stria is 7-8 in 5 μm.


Encyonema temperei

Encyonema turgidum var. ventricosum
Cymbella muelleri f. ventricosum
Encyonema stoermeri

  1. Ventral margin distinctly gibbous
  2. Valve terminations moderately rounded
  3. Central, dorsal striae 11-12 in 10 µm
  4. Rows of dorsal areolae closest to the central area oval, becoming lineolate

Asymmetrical biraphid - Valves are strongly dorsi-ventral. The dorsal margin is broadly arched, while the ventral margin is distinctly gibbous. The number of dorsal, central striae is important in distinguishing this species from similar species, as well as the density of areolae in a central, dorsal striae. Ventrally, central striae number 9 in 10 μm, and distal striae number 5 in 5 μm. The density of areolae within a central, dorsal stria is 9 in 5 μm.


Encyonema triangulum

Cymbella triangulum

  1. Valves elliptic-lanceolate
  2. Apices acute
  3. Areolae coarse

Asymmetrical biraphid - Encyonema triangulum has broad, elliptic-lanceolate valves with acute apices. The areolae are extremely coarse and number 8-10 in 10 µm.


Encyonema yellowstonianum

  1. Ventral margin slightly expanded
  2. Valves relatively narrow
  3. Central, dorsal striae 10-11 in 10 µm
  4. Rows of dorsal areolae closest to the central area oval, becoming lineolate

Asymmetrical biraphid - Valves are strongly dorsi-ventral. The dorsal margin is broadly arched, while the ventral margin is slightly expanded. The number of dorsal, central striae is important in distinguishing this species from similar species, as well as the density of areolae in a central, dorsal striae. Ventrally, central striae number 10-11 in 10 μm, and distal striae number 5 in 5 μm. The density of areolae within a central, dorsal stria is 8 in 5 μm.


Encyonopsis aequaliformis

  1. Valves lanceolate to elliptic-lanceolate
  2. Apices capitate
  3. Central area small
  4. Valves >20 µm in length

Asymmetrical biraphid - Encyonopsis aequaliformis has lanceolate to elliptic-lanceolate valves, with capitate apices. Valves are greater than 20 µm in length. The central area is small and somewhat variable within a population.


Encyonopsis aequalis

  1. Valves lanceolate
  2. Apices sub-rostrate
  3. Central area small
  4. Valves >20 µm in length

Asymmetrical biraphid - Encyonopsis aequalis has lanceolate valves more than 20 µm in length with sub-rostrate apices. The central area is small.


Encyonopsis albertana

  1. Valves narrowly lanceolate
  2. Ventral margin flat or weakly arched
  3. Apices rostrate
  4. Striae 20-24 in 10 μm
  5. Valves mostly < 20 µm long

Asymmetrical biraphid - Encyonopsis albertana has narrowly lanceolate and moderately dorsiventral valves that are generally less than 20 µm long and with rostrate apices. The ventral valve margin is flat or weakly arched. Striae number 20-24 in 10 μm.


Encyonopsis cesatii

  1. Valves narrowly lanceolate
  2. Valves 4.6-6.0 µm wide
  3. Apices subrostrate
  4. Central area small

Asymmetrical biraphid - Encyonopsis cesatii has narrowly lanceolate valves with subrostrate apices. Valve width ranges from 4.6-6.0 µm. The central area is small and asymmetric. Striae number 16-22 in 10 µm.


Encyonopsis czarneckii

  1. Valves linear-lanceolate
  2. Apices capitate
  3. Central area small, asymmetric
  4. Valves usually >20 µm in length

Asymmetrical biraphid - Encyonopsis czarneckii has linear-lanceolate valves, with capitate apices. Valves are generally more than 20 µm in length. The central area is small and asymmetric. Striae number 22-26 in 10 µm.


Encyonopsis dakotae

  1. Valves linear to linear-lanceolate
  2. Apices capitate
  3. Central area small, asymmetric
  4. Valves >20 µm in length

Asymmetrical biraphid - Valves of E. dakotae are linear to linear-lanceolate with capitate apices. Valves are more than 20 µm in length. The central area is small and asymmetric. Striae number 18-23 in 10 µm.


Encyonopsis descripta

Cymbella descripta

  1. Valves linear-lanceolate
  2. Apices capitate
  3. Central area large, round, symmetric
  4. Valves >20 µm in length

Asymmetrical biraphid - Encyonopsis descripta has linear-lanceolate valves with capitate apices. Valves are more than 20 µm in length. The central area is large, round and nearly symmetric.


Encyonopsis descriptiformis

  1. Valves lanceolate
  2. Apices rostrate to apiculate
  3. Central area large, round
  4. Valves >20 µm in length

Asymmetrical biraphid - Encyonopsis descriptiformis has lanceolate valves more than 20 µm in length, with rostrate to apiculate apices. The central area is large, rounded and nearly symmetric.


Encyonopsis falaisensis

Cymbella falaisensis

  1. Valves linear-lanceolate
  2. Apices subrostrate
  3. Central area moderately large

Asymmetrical biraphid - Encyonopsis falaisensis has linear-lanceolate valves with short subrostrate apices. The central area is moderately large.


Encyonopsis hustedtii

  1. Valves linear to linear-lanceolate
  2. Apices capitate
  3. Central area round
  4. Valves <20 µm in length

Asymmetrical biraphid - Encyonopsis hustedtii has linear to linear-lanceolate valves with capitate apices. Valves are less than 20 µm in length. The central area is round and variable in size. Striae number 23-26 in 10 µm.


Encyonopsis krammeri

  1. Valves narrowly lanceolate
  2. Ventral margin flat or weakly convex
  3. Apices rostrate
  4. Valves mostly <20 µm in length

Asymmetrical biraphid - Encyonopsis krammeri has narrowly lanceolate valves with rostrate apices. Valves are generally less than 20 µm in length. Valves are moderately dorsiventral with a strongly arched dorsal margin and a flat, or weakly convex, ventral margin. Striae number 25-30 in 10 μm.


Encyonopsis lacuscaerulei

  1. Valves linear
  2. Valve margins triundulate or concave
  3. Terminal raphe fissures very prominent
  4. Apices deflected ventrally

Asymmetrical biraphid - Encyonopsis lacuscaerulei has linear valves with triundulate or concave margins. Terminal raphe fissures are very prominent and hooked towards the ventral margin. The apices are deflected ventrally.


Encyonopsis microcephala

  1. Valves asymmetrical to the apical axis
  2. Apices protracted
  3. Striae parallel on the dorsal margin
  4. Striae radiate on the ventral margin

Asymmetrical biraphid - Valves are asymmetrical to the apical axis. The apices are protracted and relatively large compared to the size of the valve, broadly rounded, and curved slightly towards the dorsal margin. The axial area narrow. Striae are parallel on the dorsal margin, radiate on the ventral margin and number 22-24 in 10 µm.


Encyonopsis neerlandica

  1. Valves lanceolate to rhombic-lanceolate
  2. Apices rostrate to subcapitate
  3. Central area absent

Asymmetrical biraphid - Encyonopsis neerlandica has small lanceolate to rhombic-lanceolate valves, with rostrate to subcapitate apices. A central area is absent. Striae number 24-28 in 10 μm.


Encyonopsis stafsholtii

  1. Valves rhombic-lanceolate
  2. Apices gradually protracted
  3. Central area small, asymmetric

Asymmetrical biraphid - Encyonopsis stafsholtii has rhombic-lanceolate valves 25-45 µm long. The apices are gradually protracted and narrowly subrostrate. The central area is small and asymmetric. Striae number 22-25 in 10 µm.


Encyonopsis subminuta

  1. Valves slightly asymmetrical to the apical axis
  2. Apices protracted
  3. Axial area very narrow
  4. Central area absent

Asymmetrical biraphid - Valves 10-15 µm long by 3-4 µm wide, slightly asymmetrical to the apical axis. Apices are protracted, relatively narrow and short. The axial area is very narrow and linear and the central area is absent. Striae are radiate to nearly parallel.


Encyonopsis subspicula

  1. Valves weakly dorsiventral
  2. Stigma present
  3. Striae 16-20 in 10 µm

Asymmetrical biraphid - Encyonopsis subspicula has lanceolate, weakly dorsiventral valves. Valves are 5.7-8.7 µm wide. A single stigma is present. Striae number 16-20 in 10 µm.


Encyonopsis treinishii

  1. Valves rhombic-lanceolate
  2. Striae 12-17 in 10 µm
  3. Striae sinuous near center
  4. Usually, one stigma present

Asymmetrical biraphid - Encyonopsis treinishii has rhombic-lanceolate valves that are 7.6-10.3 µm wide. Striae number 12-17 in 10 µm and are sinuous near the valve center. One, or rarely two, stigmata are present on the dorsal side of the central area.


Entomoneis alata

Amphiprora alata

  1. Junction line a series of subequal dots and swellings
  2. Striae 15-18 in 10 µm
  3. Areolae more widely spaced on keel than on valve face

Asymmetrical biraphid - Entomoneis alata has a junction line composed of several sub-equal dots and swellings. The striae number 15-18 in 10 µm. Areolae within a stria are more widely spaced on the keel than they are on the valve face.


Entomoneis ornata

  1. Junction line with a few large and irregular swellings
  2. Striae 20-24 in 10 µm
  3. Areolae on keel more widely spaced than areolae on valve face

Asymmetrical biraphid - Entomoneis ornata has a junction line composed of a few large and irregularly shaped swellings. Striae number 20-24 in 10 µm. Areolae within a stria are more widely spaced on the keel than on the valve face.


Entomoneis paludosa

  1. Junction line contains a single bulge
  2. Striae 20-26 in 10 µm
  3. Areolae ~30 in 10 µm on both valve face and keel

Asymmetrical biraphid - The junction line of Entomoneis paludosa has a single bulge or swelling. Striae number 20-26 in 10 µm, with approximately 30 areolae in 10 µm on both valve face and keel.


Entomoneis punctulata

Entomoneis paludosa var. punctulata

  1. Frustules small and weakly silicified
  2. Junction line short and curved near the terminal portion of each lobe of the keel
  3. Striae very fine

Asymmetrical biraphid - Entomoneis punctulata has small and weakly silicified valves with faint markings and an abbreviated junction line near the terminus of each lobe of the keel. Striae are very fine and number 36-40 in 10 µm.


Envekadea metzeltinii

  1. Raphe sigmoid
  2. Axial costae present
  3. Striae radiate, except at apices

Symmetrical biraphid - Valves are linear with almost parallel margins. The raphe is sigmoid, with small, straight proximal raphe ends and distal raphe ends hooked to opposite sides. Striae are radiate throughout, and weakly bent. Sortened central striae are arranged in a complex pattern. Near the apices, clear shift in stria orientation is visible.


Epithemia adnata

  1. Striae 12-14 in 10 μm
  2. Costae 3-4 in 10 μm
  3. Raphe canal lies against ventral margin at distal ends of valve arching toward the dorsal margin in valve center
  4. Central arch of canal approximately 3-6 μm above the ventral margin reaching less than half the distance to the dorsal margin

Epithemioid - Valves are dorsiventral, with rounded to rostrate ends. Striae 12-14 in 10 μm, costae are 3-4 in 10 μm with 3-7 striae between costae. Dorsal margin is strongly convex and ventral margin is moderately concave. Raphe canal lies against the ventral margin at distal ends of the valve arching toward the dorsal margin in valve center. The central arch of the canal is approximately 3-6 μm above the ventral margin reaching less than half the distance to the dorsal margin.


Epithemia reicheltii

  1. Valves strongly dorsiventral
  2. Ends rounded
  3. Raphe canal straight
  4. Striae 14-15 in 10 μm

Epithemioid - Valves are asymmetric to the apical axis and dorsiventral. The valve ends are rounded. The straight raphe canal lies close to the dorsal margin. Striae number 14-15 in 10 μm and costae number 3-4 in 10 μm.


Epithemia sorex

  1. Valves strongly dorsiventrally arched
  2. Raphe canal arches almost to the dorsal margin
  3. Striae 12-15 in 10 μm
  4. Cells relatively small

Epithemioid - Valves are strongly dorsiventrally arched and are 20-33 μm long and 7.3-9 μm wide. Valves taper toward rounded to rostrate ends. Striae are 12-15 in 10 μm and costae are 6-8 in 10 μm. There are 2 (sometimes 3) striae between costae. The dorsal margin is strongly convex and the ventral margin is weakly concave. The raphe canal lies against the ventral margin at distal ends of the valve and arches toward the dorsal margin in the valve center. The central arch of the canal reaches almost to the dorsal margin.


Epithemia turgida

  1. Striae 8-10 in 10 μm
  2. Costae 4-5 in 10 μm
  3. Raphe canal at ventral margin at distal ends
  4. Central arch of the canal approximately 7-8 μm above the ventral margin

Epithemioid - Striae are 8-10 in 10 μm and costae are 4-5 in 10 μm, with 2-3 striae between costae. The ventral margin is slightly concave. The raphe canal lies against the ventral margin at distal ends of the valve and arches toward the dorsal margin in the valve center. The central arch of the canal is approximately 7-8 μm above the ventral margin reaching almost half the distance to the dorsal margin.


Eucocconeis alpestris

Achnanthes flexella var. alpestris
Achnanthes alpestris
Eucocconeis flexella var. alpestris

  1. Valves parallelogram-shaped
  2. Raphe oblique to apical axis
  3. Striae 25-30 in 10 μm

Monoraphid - Valves are rectangular-elliptical with slanted ends or in the shape of a parallelogram. Raphe valve has a transversely rectangular central area. Raphe is oblique to the apical axis of the valve. Central area on rapheless valve is large, hexagonal to diamond-shaped or rounded. Striae are slightly radiate, or radiate on one side of the valve, but parallel to slightly convergent on the other side, 25-30 in 10 μm.


Eucocconeis americana

  1. Valves flat, elliptic-lanceolate
  2. Valves 7.8-13.4 µm wide
  3. Apices subrostrate
  4. Central area on raphe valve large, symmetric, transversely elliptic to rectangular
  5. Central area on rapheless valve large hexagonal

Monoraphid - Valves are elliptic-lanceolate with flat faces and subrostrate apices. Valves are 7.8 to 13.4 µm in width. The central area on the raphe valve is large, symmetric and transversely elliptic to rectangular. The raphe is straight to slightly sigmoid with terminal fissures bent in opposite directions. The rapheless valve has a narrow sigmoid axial area and large hexagonal central area.


Eucocconeis flexella

Achnanthes flexella

  1. Frustules large, 18-40 μm long
  2. Frustules strongly bent
  3. Striae 22-24 in 10 μm

Monoraphid - Frustules are large and strongly bent. Valves are elliptical-lanceolate with slightly drawn-out ends and deep mantles. The raphe valve has lanceolate-rhomboid central area. The rapheless valve has a large rectangular or hexagonal central area. The striae are strongly radiate on raphe valve and slightly radiate on rapheless valve, 22-24 in 10 μm.


Eucocconeis laevis

  1. Frustules strongly bent
  2. Asymmetrical central area on raphe valve
  3. Central area on rapheless valve large, often asymmetrical and expanded to one or both margins
  4. Striae 25-35 in 10 μm

Monoraphid - Frustules are often strongly bent in the girdle view. Valves are elliptical-lanceolate with slightly drawn-out ends. Raphe valve has an asymmetrical central area. Rapheless valve has a large central area of variable shape, often asymmetrical and expanded to one or both valve margins. Sometimes a shallow depression is visible on one side of the central area.


Eunotia areniverma

  1. Dorsal margin broadly arched
  2. Apices broadly rounded
  3. Hyaline line at ventral margin

Eunotioid - The dorsal margin is broadly arched, although the dorsal margin of smaller valves is more highly arched than the dorsal margin of larger valves. The apices are broadly rounded. The apices are usually unconstricted (not “set off”), but the largest valves may have slightly constricted apices. The striae are nearly parallel and are interrupted by a hyaline line at the ventral margin.


Eunotia bilii

  1. Dorsal margin undulate
  2. Apices terminate bluntly
  3. Striae on dorsal margin short and irregular

Eunotioid - The dorsal margin with 5 to 8 undulations. The ventral margin is straight or slightly concave. The ends are protracted but terminate bluntly, with a slight ventral curvature at the ends. Irregular, shortened striae are present on the dorsal margin near the center valve.


Eunotia boomsma

  1. Dorsal margin broadly biundulate
  2. Apices broadly rounded
  3. Helictoglossae visible in LM

Eunotioid - The dorsal margin of E. boomsma is biundulate, in large to small specimens. The apices are broadly rounded. Helictoglossae are visible in the LM. The striae are slightly radiate.


Eunotia canicula

  1. Ventral margin straight to weakly concave
  2. Dorsal margin convex
  3. Apices acutely rounded and nose-like
  4. Helictoglossae equidistant from midpoint of apical axis and apices

Eunotioid - The ventral margin of Eunotia canicula is straight to weakly concave. The dorsal margin is convex. The apices are acutely rounded, tapered, subrostrate and nose-like in appearance. The apices are delimited by a very slight change in the slope of the dorsal margin. Helictoglossae are equidistant from the midpoint of the apical axis and the ends.The helictoglossae are also set in, forming a ventral indentation. Striae are slightly radiate.


Eunotia cataractarum

  1. Ventral margin concave
  2. Dorsal margin slightly convex
  3. Apices capitate
  4. Striae parallel to slightly radiate
  5. One apical rimoportula

Eunotioid - Valves with a concave ventral margin. The dorsal margin is slightly convex and set off dorsally by a steep sloping shoulder. Apices are capitate and rounded. Striae are parallel to slightly radiate. One apical rimoportula at the center of the apex (visible in SEM), with a distinct external pore. .


Eunotia diadema

  1. Dorsal and ventral margins highly arched
  2. Dorsal margin with 6 undulations
  3. Apices broad, obtusely rounded

Eunotioid - Eunotia diadema has large valves with highly arched dorsal and ventral margins. The dorsal margin has a constant 6 undulations. Apices are broad and obtusely rounded.


Eunotia enischna

  1. Ventral margin concave
  2. Dorsal margin convex
  3. Apices capitate
  4. Striae indistinct, radiate
  5. Raphe short

Eunotioid - Eunotia enischna valves are small and slender. The ventral margin is concave and the dorsal margin is convex. The apices are defined by a marked change in slope on the dorsal margin. The apices are capitate, rounded and dorsally recurved. The striae of E. enischna are radiate and very faint, even though the striae density is not high. The aerolae can not be resolved in the LM. The raphe is short and curves on to the valve face.


Eunotia exigua

  1. Ventral margin concave
  2. Dorsal margin convex
  3. Apices protracted and dorsally reflexed
  4. Distal raphe curves onto valve face

Eunotioid - Ventral margin is concave. In smaller specimens the ventral margin is slightly concave or straight. Dorsal margin is strongly convex. Apices are protracted, and frequently strongly dorsally reflexed. Apices of shorter specimens are more obtusely rounded. Distal raphe end curves a short distance on to the valve face.


Eunotia faba

  1. Valves variably asymmetric to transverse axis
  2. Apices broadly rounded
  3. Helictoglossae relatively distant from apices

Eunotioid - Eunotia faba has stout valves with broadly rounded, unprotracted apices. Valves are 8.1-11.1 µm wide.


Eunotia gibbosa

  1. Valves bilobed
  2. Narrow, central isthmus present

Eunotioid - Eunotia gibbosa has bilobed valves with a narrow central isthmus. Valves are nearly symmetric with regard to the apical axis.


Eunotia hexaglyphis

  1. Valves weakly arched
  2. Dorsal undulations 4 to 6
  3. Apices with broad, shallow notch

Eunotioid - Eunotia hexaglyphis has large, weakly arched, and more or less linear valves with 4 to 6 bluntly pointed undulations on the dorsal side. Apices Apices are set off from the rest of the valve by broad, but shallow, notches.


Eunotia horstii

  1. Ventral margin lightly concave to nearly straight
  2. Dorsal margin convex
  3. Apices rostrate, dorsally deflected
  4. Striae parallel

Eunotioid - Eunotia horstii valves have a slightly concave, to nearly straight ventral margin The dorsal margin is convex and the apices are “set off” by a change in slope in the dorsal margin. The apices are rostrate and dorsally deflected. The distal ends of the raphe are dorsally curved. The striae are parallel.


Eunotia incisa

  1. Ventral margin straight to weakly concave
  2. Dorsal margin convex
  3. Apices acutely rounded,(nose-like)
  4. Helictoglossae set in equidistant from the ends
  5. Distal raphe ends lie on valve mantle

Eunotioid - The ventral margin of Eunotia incisa is straight to weakly concave. The dorsal margin is convex. The apices are acutely rounded, appearing ‘nose-like’ due to the inset position of the helictoglossae which are set in equidistant from the ends (symmetric to the transapical axis). The distal ends of the raphe lie on the valve mantle and terminal raphe nodules are well set in from the apices.


Eunotia kociolekii

  1. Ventral margin concave to nearly straight
  2. Dorsal margin slightly biundulate
  3. Valve apices flattened
  4. Striae radiate

Eunotioid - The ventral margin is slightly concave to nearly straight. The dorsal margin is convex and biundulate, becoming straight in smaller valves. The apices are attenuated and flattened. Striae are radiate.


Eunotia lewisii

  1. Ventral margin depressed between proximal raphe ends
  2. Stria density consistent
  3. Striae radiate distal to the terminal raphe ends
  4. Terminal raphe ends cross the valve face near the apices
  5. Helictoglossae prominent

Eunotioid - The ventral margin is depressed between the proximal raphe ends; the dorsal margin is flat and parallel to the ventral margin. Apices are rostrate. Striae are evenly spaced and parallel, becoming radiate distal to the terminal raphe ends. The raphe curves across the valve face at the apices, with a prominent helictoglossa and a thickened ridge running from the helictoglossa to the dorsal margin.


Eunotia macroglossa

  1. Helictoglossae prominent
  2. Dorsal margin convex, with apices slightly set off by a change in slope
  3. Ventral margin slightly concave to nearly straight
  4. Striae radiate at apices
  5. One apical rimoportula

Eunotioid - Valves with the ventral margin slightly concave to nearly straight, the dorsal margin evenly convex up to the rounded ends, with apices slightly set off by a change in slope of the dorsal margin. Helictoglossae prominently visible in the LM as apical thickenings. Raphe extending from helictoglossa to 20-30% of the length of the valve. Striae slightly radiate, radiate at apices. One apical rimoportula positioned nearly parallel to striae.


Eunotia microcephala

  1. Ventral margin weakly concave
  2. Dorsal margin with central undulation
  3. Apices capitate to subcapitate

Eunotioid - Ventral margins are weakly concave, with two slight swellings marking the position of the proximal raphe ends. Dorsal margins are irregular andly weakly triundulate, with the central undulation being most prominent. Valve ends are protracted and capitate to subcapitate. Helictoglossae are located close to the apices. The raphe extends in a short curve on to the valve face.


Eunotia montuosa

  1. Dorsal margin biundulate
  2. Ventral margin concave
  3. Ends dorsally recurved
  4. Striae radiate
  5. Shorter, more radiate striae distal to raphe ends

Eunotioid - The dorsal margin is strongly biundulate with two acutely pointed peaks. The ventral margin is slightly concave with subapical swellings. The valve ends are dorsally recurved and apically flattened. Striae are radiate. Shorter, more radiate striae are present distally to the distal raphe ends. The distal raphe is slightly curved and clearly visible in the LM.


Eunotia mydohaimasiae

  1. Ventral margin concave
  2. Dorsal margin convex
  3. Dorsal margin with change in slope near apices
  4. Ends narrow
  5. Striae radiate

Eunotioid - Valves are concave on the ventral margin and convex on the dorsal margin. The apices are set off by a change in slope of the dorsal margin. The ends are narrowed, extended, and rostrate. Striae are radiate.


Eunotia naegelii

  1. Valves moderately arched
  2. Valves narrow toward apices
  3. Apices slightly dorsally recurved
  4. Distal raphe end curves 180º

Eunotioid - Valves moderately arched. Valves become progressively narrower toward the apices. The apices slightly recurved toward the dorsal margin. The distal raphe end curves on to the valve face, then bends 180º and continues a short distance towards the proximal raphe ends.


Eunotia nymanniana

  1. Valves are strongly arched
  2. Margins similar in shape, equidistant
  3. Apices recurved
  4. Raphe curves onto valve face
  5. Striae evenly spaced, parallel

Eunotioid - Valves are strongly arched, more so in larger specimens. The margins are equally spaced along length of valve. The apices are rounded, protracted and dorsally recurved. The distal raphe ends curve onto the valve face, extending a little less than halfway to the dorsal margin. Striae are evenly spaced, and parallel along the length of the valve, becoming radiate at the apices.


Eunotia obliquestriata

  1. Ventral margin concave
  2. Dorsal margin convex
  3. Dorsal margin lacking shoulder
  4. Apices slightly narrowed
  5. Striae distinctly oblique

Eunotioid - The ventral margin is concave, while the dorsal margin is convex and lacks a shoulder, or change in slope. The apices are slightly narrowed and rounded. The striae are distinctly oblique on the valve mantle and in the valve center, and become radiate near the ends.


Eunotia orthohedra

  1. Ventral margin with subapical swellings
  2. Dorsal margin straight
  3. Angular shoulders subtending the apices
  4. Apices capitate, dorsally recurved
  5. Striae indistinct, radiate

Eunotioid - The ventral margin is slightly concave with subapical swellings at the proximal raphe ends. The dorsal margin is flattened with angular shoulders subtending the apices. Valves are narrow and 4.2 – 6.0 times longer than wide. The apices are capitate, dorsally recurved and rounded. The raphe is short and curves on to the valve face. The striae are radiate and may be faint in appearance.


Eunotia paludosa

Himantidium paludosum

  1. Valves weakly curved
  2. Ventral margin concave
  3. Ventral margin with subapical swellings
  4. Apices rounded, slightly reflexed

Eunotioid - Valves are weakly curved. Ventral margins are straight in smaller specimens and moderately concave in mid-size to large specimens. Ventral margins of larger specimens with barely visible swellings marking the position of the proximal raphe ends. Valve apices are rounded and slightly dorsally reflexed.


Eunotia papilioforma

  1. Valve asymmetric to apical axis
  2. Position of the helictoglossae asymmetric to transapical axis
  3. Apices 'nose-like'
  4. Distal raphe curves onto valve face
  5. One apical rimoportula

Eunotioid - Valves asymmetric to the apical axis, that is, one apex is wider than the other. The helictoglossae are removed from the apices, in a position that is asymmetric to the transapical axis. The apices are rounded, tapered and combined with the inset helictoglossae, the apices .appear ‘nose-like’. Distal raphe curves onto the valve surface. One apical rimoportula is present at the wider valve end.


Eunotia rhomboidea

  1. Rhomboid in girdle view
  2. Asymmetric to the apical and transapical axis
  3. One apex wider than the other
  4. Helictoglossae close to or a short distance from apices
  5. Distal raphe curves on to valve face

Eunotioid - Frustules appear rhomboid in girdle view. Valves are asymmetric to the apical and transapical axes, with one apex wider than the other. The ventral margin is straight to weakly concave, and the dorsal margin is convex. The apices are rounded. The helictoglossae lie close to or are a short distance from the apices. The distal raphe end curves a short distance onto the valve face.


Eunotia richbuttensis

  1. Dorsal margin slightly biundulate
  2. Apices bluntly rounded
  3. Striae mostly parallel
  4. Irregular short striae on the dorsal margin

Eunotioid - The dorsal margin is slightly biundulate in larger valves. The dorsal margin of smaller valves is almost flat. At the smallest end of the size range, the dorsal margin is convex. The valve apices are bluntly rounded and slightly “set off” by a gradual change in slope of the dorsal margin. The striae are mostly parallel and curved towards the apices distal to the the helictoglossa. often with a few irregular, short striae on the dorsal margin.


Eunotia rushforthii

  1. Ventral margin slightly concave to nearly straight
  2. Dorsal margin with faint swelling
  3. Apices acutely rounded
  4. Raphe curves onto valve face
  5. Striae slightly radiate

Eunotioid - E. rushforthii valves have a slightly concave to nearly straight ventral margin. The dorsal margin is convex with a very slight central swelling. The apices are acutely rounded and very slightly delimited from the rest of the valve. The raphe curves onto the valve face. Striae are slightly radiate.


Eunotia serra

  1. Valves very large
  2. Dorsal and ventral margins highly arched
  3. Dorsal margin with 6 to 22 undulations

Eunotioid - Eunotia serra has very large valves with highly arched dorsal and ventral margins. The dorsal margin has 6 to 22 bluntly pointed and evenly spaced undulations.


Eunotia subherkiniensis

  1. Dorsal margin biundulate
  2. Apices obliquely capitate
  3. Apices dorsally recurved
  4. Striae radiate

Eunotioid - The dorsal margin is convex and biundulate.The apices are obliquely capitate and dorsally reflexed in medium-sized to larger valves, truncate in smaller valves. Striae are radiate. Internally, the openings of the areolae are aligned in a narrow groove (SEM).


Eunotia sudetica

  1. Helictoglossae relatively distant from apices
  2. Dorsal margin nearly flat
  3. Apices rostrate

Eunotioid - Eunotia sudetica has somewhat convex, to nearly flat dorsal margins. The apices are rostrate, or nose-shaped, and helictoglossae lie some distance from the apices. Striae number 10-15 in 10 µm.


Eunotia tenella

Eunotia exigua var. tenella

  1. Ventral margin concave
  2. Dorsal margin parallel
  3. Apices broadly rounded to truncate
  4. Helictoglossae close to apices
  5. Distal raphe curves onto valve face

Eunotioid - Ventral margin is slightly concave. Dorsal margin is parallel in longer specimens to more convex in smaller specimens. Apices are broadly rounded to truncate. Helictoglossae are positioned close to the apices. Distal raphe ends curve slightly on to the valve face.


Eunotia tetraodon

  1. Dorsal and ventral margins highly arched
  2. Dorsal margin with 4 undulations
  3. Apices broad, obtusely rounded

Eunotioid - Eunotia tetraodon has large valves with highly arched dorsal and ventral margins. The dorsal margin has a constant 4 undulations. Apices are broad and obtusely rounded.


Eunotia trinacria

Eunotia paludosa var. trinacria

  1. Valves elongate triangular
  2. Ventral margin straight to weakly concave
  3. Dorsal margin with slight central undulation

Eunotioid - Valves are elongate-triangular, becoming more linear in larger specimens. Ventral margins are straight to weakly concave. Dorsal margins are slightly convex, with a slight central undulation. Valve ends are weakly subcapitate, subrostrate and not off, or only slightly set off, from the main part of the valve.


Eunotia triodon

  1. Valves moderately arched
  2. Dorsal margin with three undulations
  3. Apices protracted, broadly rounded

Eunotioid - Eunotia triodon has moderately arched valves with three broadly rounded, rather than deeply rounded, undulations on the dorsal margin. Apices are protracted and broadly rounded, but more narrow than the undulations.


Eupodiscus radiatus

Aulacodiscus radiatus
Roperia radiata

  1. Valves circular with hexagonal areolae uniform across valve
  2. Prominent ocelli near valve margin, usually four
  3. Rimoportulae on valve margin
  4. Valve margin scalloped, forming circumferential ridge

Centric - Valves circular with hexagonal areolae uniformly distributed across valve; a distinct central area is absent. Prominent ocelli are present near the valve margin, usually 4, sometimes 3-6. Rimoportulae may be visible on interior valve interspersed with ocelli, 1-2 between each pair of consecutive ocelli. The valve margin is scalloped, forming a narrow circumferential ridge.