sylviaslee's Identifications

2023-22 Silver Lake Fen-Low Flark Chara Epiphytes. Proximal raphe ends bilaterally deflected. Not Neidium bisculcatum because it is found in fens, not acidic environments. Image 4 is of a tilted, girdle view. Also, stria density in this variety is consistently lower.

2nd image is an internal view, as indicated by proximal raphe ends deflecting clockwise.

scale bar 10 μm

slide 2023-45
Piston Core (0-1cm)
Little Miller's Bay
scale bar 10µm

image 3 is tilted for view of the raphe along the valve margin.

Valves asymmetric to the transapical axis, one side is more pointed and the other is more rounded. The raphe canals are very visible.

the valve margin contains 7-8 ribs/ 50 µm, the striae are not visible at 100x magnification

These specimen came from the Kissimmee river. The valves are very small and ovoid with broadly rounded apices. Compared to Staurosirella lapponica, my specimen are too small. According to KLB 2/3 lapponica are 10-30µm long and my specimen range from 5-7µm long. This species was also described in a nearby county, Palm Beach County, in the Stoermer et al. 1992 study.

slide 2023-19
Periphyton from Silver Lake Fen High Flark

scale bar 10µm

Image 2 includes a semi-attached frustule.

Fibulae density is 7 per 10µm

Central nodule is visible. Width is 5-6, which is a larger value than what is on Diatoms of North America reference.

These came form a periphyton sample in the Kissimmee river. Valves are elliptical lanceolate with truncate to broadly rounded apices. They have a distinct sinus or horseshoe shaped depression with a flap of silica over creating a double horseshoe.

Cylindrical frustules are seen joined face-to-face. Circular areolae form striae that appear to curve to the right. Thickly silicified valves appear to have resulted from a narrow microscope aperture when capturing, giving it the appearance of a thicker valve than the species' DONA page.
DONA measurements report a diameter range from 4-17 µm.

Little Sioux River
Sample type: Epipelon
Scale bar=10µm
These specimen are in girdle views

Reference:
Stepanek, J., Kociolek, P. (2011). Amphora copulata. In Diatoms of North America. Retrieved June 13, 2023, from https://diatoms.org/species/amphora_copulat

Grove Lake
Sample type: Zygnemetales Epiphytes
Scale bar: 10µm
Reference: Morales, E. (2010). Staurosirella leptostauron. In Diatoms of North America. Retrieved June 13, 2023, from https://diatoms.org/species/staurosirella_leptostauron

These specimen came from an epidendron sample from a stream on the North 40 trail. The valves are lunate shaped with convex dorsal margins. The apices are bent towards the dorsal side with a protracted and rounded shape. The raphe is on the dorsal side right next to the mantle. My samples have a breadth width that is 0.7µm wider than the reference samples, but all other measurements and descriptions are similar.

Slide 23-36

Rhopalodia gibberula var. vanheurckii

Silver Lake Fen- High Fark
Sample type: Surface biofilm
Scale bar: 10µm
Reference; Kociolek, P. (2011). Nitzschia amphibia. In Diatoms of North America. Retrieved June 09, 2023, from https://diatoms.org/species/nitzschia_amphibia

These specimen are from a phytoplankton tow in Silver lake. These are centric diatoms with cylindrical frustules. They have prominent coarse, slightly diagonal areolae on their mantle. The 3rd and 4th pictures show their long separation spines. My specimen differ from the var. ambigua because ambigua have 17-22 areolae/10µm and my specimen have 12 areolae/10µm.

Slide 23-23

scale bar = 10µm
Observed in ~2600-yr-old core sample sediments from a coastal lagoon on Montague Island, Prince William Sound, Alaska.

Now Stephanocyclus meneghiniana.
Distinctive chambered striae around the margin (generally 7-8/10µm).
In two of the images, the central fultoportulae are visible. This species usually contains 1-4.

scale bar = 10µm

Monoraphid diatom species with both a raphe and rapheless valve.
Valves are elliptical.
Raphe valves feature a central raphe and an intricately decorated valve circumference. They contain a thicker transapical gap in the striae at the valve center. Rapheless valves feature a central, linear sternum. Striae are biseriate, parallel and slightly radiate at the apices.

scale bar = 10µm

Valves are narrow and linear with rostrate to subcapitate apices. Striae are straight and alternate. There is a narrow linear central axial area. In smaller specimen there is an asymmetric central gap in the center of the valve, and in larger specimen there is a larger gap with ghost striae visible.

Another reference: Morales, E. (2010). Fragilaria vaucheriae. In Diatoms of North America. Retrieved June 12, 2023, from https://diatoms.org/species/fragilaria_vaucheriae

scale bar = 10µm

Valves are bent at the central node creating asymmetry along the apical axis. Apices are rostrate to capitate, protracted, and bend slightly to the dorsal side. Fibulae are present and spaced unevenly along the ventral side of the valve. Valves can be quite large (~150µm) however the specimen pictured here range from 61-72µm.

scale bar = 10µm

Apices are angled towards the ventral side of the valve. The striae density/10µm is slightly lower for my specimen than what is recorded in the original description (see reference). Proximal raphe ends deflect slightly to the dorsal side.