SPECIES starting with "E"

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.

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.

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.

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

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.

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.

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.

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

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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. .

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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).

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.

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.

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.

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.