SPECIES starting with "G"

Symmetrical biraphid - Valves are small elliptical and small. The striae are radiate. Two rows of annulae are present at the poles, but may be difficult to discern. The presence of a stigma in the central area is a variable character within the species.

Symmetrical biraphid - Valves are elliptical-lanceolate with rostrate to capitate apices. Striae are radiate and often deflected, or bent. Short and long striae alternate in the central part of the valve. The presence of a stigma in the central area is a variable feature in the species.

Symmetrical biraphid - Valves triundulate with rostrate to subcapitate ends. The central area is expanded laterally with 2-4 shortened striae at the valve margin. Striae are radiate near the center of the valve, becoming parallel near the ends. Two to three rows of annulae are present at each apex of the valve.

Symmetrical biraphid - Valves are elliptical-lanceolate with subrostrate ends, 5.0-7.5 µm wide and 11-23 µm long. The central area is small, without isolated areolae. Striae are uniseriate, radiate, and number 16-23 in 10 µm. The annulae form three-four rows at each pole.

Symmetrical biraphid - Valves are elliptical-lanceolate, often slightly dorsiventral, with narrowly rostrate or subrostrate ends, 7.0-9.0 µm wide and 15-25 µm long. The central area is small, with one to five isolated areolae. Striae are radiate, and number 18-22 in 10 µm. The annulae form three-four rows at each pole.

Symmetrical biraphid - Valves are lanceolate with subrostrate broadly rounded ends, 6.0-8.5 µm wide and 16-27 µm long. The central area is small, formed by one shortened stria on each side of the valve, with an isolated stigma. Striae are radiate, 16-18 in 10 µm. The annulae form three rows at each pole.

Asymmetrical biraphid - Larger valves are lanceolate-clavate and angular, with a slightly protracted headpole and broadly rounded footpole. The raphe is lateral and undulate. Longitudinal lines are distinct and positioned near the axial area. A single, distinct stigma is present in the central area.

Asymmetrical biraphid - Valves trullate, with broadest portion of the valve outline located towards the footpole from the central nodule. Valves are relatively small, 34-67 um in length. Striae number 10-13 in center and 14-16 at the poles.

Asymmetrical biraphid - Valves are broadly lanceolate-clavate, with an apiculate headpole and a rounded footpole. Longitudinal lines are present on either side of the axial area, and may be indistinct in some specimens.

Asymmetrical biraphid - Valves are lanceolate-clavate. Smaller valves are elliptical-clavate, with the headpole protracted slightly. Striae are radiate at the central portion of the valve and strongly radiate at the poles. A small, barely circular central area with a single stigma is present. Longitudinal lines are distinct near the axial area, less so at the apices.

Asymmetrical biraphid - Valves are clavate. An isolated stigma is present in the central area, at the end of one stria. The helictoglossae are distinct. Striae are doubly-punctate, although this feature is not discernible in LM.

Asymmetrical biraphid - Valves are large and robust, strongly lanceolate-clavate with broadly rounded headpole and narrow, rounded footpole. The axial area is narrow and straight. The central area is relatively small, irregularly rounded and bears a single stigma. The longitudinal lines are positioned approximately one-half the way between the axial area and margin.

Asymmetrical biraphid - Valves linear-clavate. Valve length 76-160um, valve breadth 16-25um. Longitudinal lines are positioned approximately one-half the distance between the axial area and margin.

Asymmetrical biraphid - Valves broadly trullate, with broadly rounded apices. Longitudinal lines of are positioned approximately one-half the way between the axial area and margin. The striae density varies across the valve: 8-12 in 10um in the center valve, 12-14 in 10 um at the headpole, 13-16 in 10 um at the footpole.

Asymmetrical biraphid - Valves are distinctly clavate in shape. The axial area is relatively narrow, straight, widening only slightly to form a narrowly elliptical central area with a single stigma. The raphe is lateral, weakly undulate. External proximal raphe ends are dilated. Striae are evidently doubly-punctate, radiate the length of the valve. Longitudinal lines are evident on either side of the axial area, positioned 1/5-1/4 the way from the valve margin towards the axial area. At the headpole are two conspicuous spines. The footpole bears distinct apical pore fields. Septa and pseudosepta are present at the apices.

Asymmetrical biraphid - Valves are linear-clavate, with convex margins. The margins do not become tumid at the center valve. Longitudinal lines are present, located about half-way between the axial area and margin.

Asymmetrical biraphid - Valves are clavate with a broadly rounded headpole and narrow footpole. The central area is bordered by shortened striae at, or near, the valve margin. Stigmoids are absent. Striae are costate and individual areolae within a stria are not discernible. Striae are radiate.

Asymmetrical biraphid - Valves clavate. Axial area very narrow, straight, with filiform raphe. Central area rectangular with four isolated stigmoids. Striae costate, areolae not resolved. Apical pore fields appear as condensed striae.

Asymmetrical biraphid - Valves lanceolate-clavate. Valve tapers gently towards the headpole, more strongly towards the footpole especially in shorter specimens. Longitudinal lines are positioned on either side of the axial area; they are indistinct in some specimens.

Asymmetrical biraphid - Valves are lanceolate-trullate and broadest below the central nodule. The raphe is lateral and distinctly undulate. Longitudinal lines are submarginal in larger specimens and are positioned about mid way between the margin and axial area in smaller specimens.

Asymmetrical biraphid - Valves clavate, tumid at the center with two constrictions along the margin; at the headpole the valve is broad and then becomes apiculate at the headpole, the footpole is rounded. The axial area is narrow, straight, until broadening to form an irregular central area. The raphe is lateral and undulate.

Asymmetrical biraphid - Valves acuminate-apiculate and asymmetric to the transapical axis. The striae are punctate and radiate throughout to nearly parallel in the middle of the valve. Striae in the central valve are more widely spaced. On one side of the central area a stria is shortened, on the other side the central stria terminate next to the single stigma.

Asymmetrical biraphid - Valves are lanceolate-clavate, with the headpole rounded to narrowly acute. The axial area is expanded to produce a lanceolate hyaline area running the length of the valve. The central nodule is distinct and round in shape. Striae are short, radiate along the length of the valve, with each stria comprised of a single elongated areola.

Asymmetrical biraphid - Valves bluntly acuminate, with the headpole protracted and bluntly rounded. The valve is biconstricted; it is broadest near the headpole, but tumid at the center of the valve. The raphe is lateral and undulate.

Asymmetrical biraphid - Valves are acuminate-apiculate, with a small, acute to blunt protracted headpole. The broadest portion of the valve is at the headpole and/or the central portion of the valve. On one side of the central area there is a shortened stria, on the opposite side the central stria terminates at the stigma.

Asymmetrical biraphid - Valves acuminate-apiculate, with the headpole weakly expanded and protracted. The central valve is tumid. Both of the central striae are shortened, and on one side is positioned a single, isolated stigma.

Asymmetrical biraphid - Gomphonema johnsonii has lanceolate valves with narrow subapiculate apices. Striae are radiate and more widely spaced near the valve center. A single stigma is present at the end of the longest central stria. The central area is moderately large.

Asymmetrical biraphid - Valves are linear-clavate with headpole rounded and footpole narrowly rounded. The striae are strongly radiate at the footpole. The axial area is narrow at poles, widening toward the central area. The central area is broadly rectangular with shortened striae on either side. A single stigma is located in the central area.

Asymmetrical biraphid - Valves are elliptical-clavate. The headpole is slightly produced and broadly rostrate, while the footpole is rounded. The stigma opening on the inside is quite offset from the external opening. Striae are punctate, parallel to radiate and strongly radiate at the footpole. Septa and pseudosepta are present at the poles.

Asymmetrical biraphid - Valves are linear-lanceolate to clavate. Axial area is lanceolate with a linear-ellipitcal, slightly asymmetrical central area with the side opposite the stigma being larger than the side bearing the stigma. Striae are parallel to radiate at the center and towards the headpole, more strongly radiate at the footpole.

Asymmetrical biraphid - Valves are lanceolate-clavate, broadest at the center with a broadly-rounded headpole and rounded footpole. Axial area is narrowly lanceolate forming a distinct, mostly irregularly elliptical central area which possesses a single stigma. The raphe is weakly undulate and lateral. Striae are punctate, radiate to parallel. Septa are frequently observed.

Asymmetrical biraphid - Valves are linear-clavate with a broadly rounded headpole, sometime with an acute tip, footpole rounded. Striae are usually short, near the margin, but there may be isolated areolae extending towards the broad axial area. The footpole has a more dense arrangement of striae around the terminus.

Asymmetrical biraphid - Valves are linear-clavate to clavate. The headpole is narrowly rounded to nearly acute and the footpole is narrowly rounded. The axial area is lanceolate. Stigmata are absent. The central nodule is distinct and round. The striae are formed by a single areola, with an additional 1-2 isolated areolae towards the axial area. The striae are radiate, becoming parallel near the footpoles.