natashaphillips's Identifications

Scale bar = 10µm

Fragilaria mesolepta is set apart from other species in its genus by its unique silhouette: a thin valve with rostrate ends and a pinched central area with ghost or absent striae. Striae on the rest of the valve are parallel, gradually shifting to slightly radiant at the apices, and faint.

F. mesolepta may be distinguished from F. capucina by its pinched central area and more noticeably rostrate ends.

Scale Bar = 10 micrometers.

Valves clavate with thickly silicified transapical costae. The largest specimen was 51 micrometers and the smallest whole valve was 28 micrometers. The specimen on the bottom of the plate is an example of one of the valves formed during the resting stage, in girdle view. The resting stage valve measured only 25 micrometers in length, however other specimens that were not so easily photographed due to debris were slightly smaller. Width ranged from 3 - 5 micrometers at the widest point. Costae were normally 4 per 10 micrometers depending on the location measured. Stria were also variable, with counts between 17 and 19 per 10 micrometers. This variety is differentiated from M. circulare var. circulare by the capitate headpoles.

This species is commonly described using the name M. circulare var. (or f.) constrictum. The name Meridion constrictum is considered taxonomically valid and this species was described using that epithet in 1843, 37 years before Brun described this species as Meridion circulare var. constrictum.

http://www.algaebase.org/search/species/detail/?species_id=36040

Scale bar = 10µm

Fragilaria mesolepta is set apart from other species in its genus by its unique silhouette: a thin valve with rostrate ends and a pinched central area with ghost or absent striae. Striae on the rest of the valve are parallel, gradually shifting to slightly radiant at the apices, and faint.

F. mesolepta may be distinguished from F. capucina by its pinched central area and more noticeably rostrate ends.

Scale bar = 10µm

Valves are elliptical with rostrate to subrostrate ends. F. vaucheriae is readily identified by a hyaline central area, offset to one margin with striae or ghost striae still present along the other margin. In some cells, this central margin may protrude slightly or seem to cover the entire central area, making those specimens easily confused with F. capucina or Synedra rumpens. Stria are offset in an alternating pattern along the apical axis.

Scale bar = 10µm

Fragilaria mesolepta is set apart from other species in its genus by its unique silhouette: a thin valve with rostrate ends and a pinched central area with ghost or absent striae. Striae on the rest of the valve are parallel, gradually shifting to slightly radiant at the apices, and faint.

F. mesolepta may be distinguished from F. capucina by its pinched central area and more noticeably rostrate ends.

Scale bar = 10µm

F. capucina has a filiform valve and an outline that subtly narrows linearly towards the apicies. Striae are parallel, and faint or appearing absent in the central area.

F. capucina may be differentiated from F. mesolepta by its lack of a pinched central area and rounded apices.

Scale Bar = 10 micrometers.

Specimens were very large with a humped central area. The stria are radiant around the central area gradually shifting to parallel along the length of the valve. Stria become convergent around apices and are visible around the end of the raphe. The axial area is linear, tapering near the apices before opening into a hyaline area surrounding the end of the raphe. The chambered stria form longitudinal lines close to the axial area.

Scale Bar = 10 micrometers.

Valves clavate with thickly silicified transapical costae. The largest specimen was 51 micrometers and the smallest whole valve was 28 micrometers. The specimen on the bottom of the plate is an example of one of the valves formed during the resting stage, in girdle view. The resting stage valve measured only 25 micrometers in length, however other specimens that were not so easily photographed due to debris were slightly smaller. Width ranged from 3 - 5 micrometers at the widest point. Costae were normally 4 per 10 micrometers depending on the location measured. Stria were also variable, with counts between 17 and 19 per 10 micrometers. This variety is differentiated from M. circulare var. circulare by the capitate headpoles.

This species is commonly described using the name M. circulare var. (or f.) constrictum. The name Meridion constrictum is considered taxonomically valid and this species was described using that epithet in 1843, 37 years before Brun described this species as Meridion circulare var. constrictum.

http://www.algaebase.org/search/species/detail/?species_id=36040

Scale Bar = 10 micrometers.

Valves clavate with thickly silicified transapical costae. The largest specimen was 51 micrometers and the smallest whole valve was 28 micrometers. The specimen on the bottom of the plate is an example of one of the valves formed during the resting stage, in girdle view. The resting stage valve measured only 25 micrometers in length, however other specimens that were not so easily photographed due to debris were slightly smaller. Width ranged from 3 - 5 micrometers at the widest point. Costae were normally 4 per 10 micrometers depending on the location measured. Stria were also variable, with counts between 17 and 19 per 10 micrometers. This variety is differentiated from M. circulare var. circulare by the capitate headpoles.

This species is commonly described using the name M. circulare var. (or f.) constrictum. The name Meridion constrictum is considered taxonomically valid and this species was described using that epithet in 1843, 37 years before Brun described this species as Meridion circulare var. constrictum.

http://www.algaebase.org/search/species/detail/?species_id=36040

Scale Bar = 10 micrometers.

Valves are tangentially undulate with conspicuous costae more widely separated than other species of
Cyclotella. Valves display a central fultoportulae which is off center, roughly opposite of the labiate process located in the marginal area. All specimens were roughly the same size suggesting they were within the same cohort.

Scale Bar = 10 micrometers.

This species is distinguished by its lack of conspicuous ornamentation. Valve faces appear grainy due to the presence of small spines. Mantle is even all the way down the frustule and covered with small grains. Valve and mantle are covered with a smattering of rimoportulae. The specimens ranged in diameter from 10 - 18 micrometers. Mantle height ranged from 16 - 27 micrometers.

Scale Bar = 10 micrometers.

Raphe deflects dorsally at the central margin and ventrally at the apices. Raphe is located almost halfway between the dorsal and ventral margins. Striae are coarsely punctate and radiate around the central area, gradually shifting to parallel near the apices. The length of specimens ranged from 51-57 microns. Width ranged from 19-20 microns. There were between 6-10 stria per 10 microns. Valves are thickly silicified.

Scale Bar = 10 micrometers.

Valves are linear with blunt rounded apices lending the diatom a roughly rectangular appearance. Stria are very broad and widely spaced. Striae near central area are reduced in length forming a small hyaline area. Striae are slightly radiate near central area gradually shifting to slightly convergent at apices. Raphe deflects to one side at central area and sharply to the opposite side at the apices. Specimens ranged in size from 38-43 micrometers long and 9-11 micrometers wide. Stria were 5-6 per 10 micrometers. The bottom specimen is laying in girdle view. The markings on the girdle are quite common in the genus Pinnularia.