Observaciones de thrashii

Scale bar = 10µm
The headpole is broadly rounded the footpole is slightly narrowed, smaller valves under 30 µm---footpole is broadly rounded, costae present from margin to axis, distint fibulae present

Scale bar = 10µm
Valve is somewhat ellliptical with a slight rectangular shape, ends capitate, central area is large and diamond shaped, striae are radiate, distinctive raphe that deflects at ends, rounded ends in central region

Scale bar = 10 µm
Other species classifications considered; small size differentiates from other species and varieties, valve is broadly elliptical, the central region has an empty area slightly more open to one side, there are longitudinal canals that surround the raphe and central area, there is a rib enclosing the raphe, striae are radiate, the striae appear to be biseriate alveoli
note: the striae are difficult to see at 100x, biseriate striae are not as obvious as in Krammer and Lange-Bertalot 1986 reference

Scale bar = 10 µm
the headpole is rostrate, costae are prominent and irregular in partition, end blunt or narrowed to a smaller rostrate footpole

note: there are some discrepancies with authority nomenclature "Combination also introduced by Brun (1880). Priority remains to be established." - (30 Jun 2014) - M.D. Guiry
http://webcache.googleusercontent.com/search?q=cache:88lbV6aDOocJ:www.algaebase.org/search/species/detail/%3Fspecies_id%3D31490+&cd=3&hl=en&ct=clnk&gl=us

Scale bar = 10 µm
valves are elliptical with capitate ends, the central area is rounded, areolae are punctate, decussate striae creating diamond like angles
note: images presented differ from those of the reference---ends of specimens in Iowa have more capitate ends than those in Oregon specimens

Scale bar = 10 µm
lanceolate shape---slightly rhombus like, apices are rounded, somewhat rostrate, very fine striae--too small to measure on 100x
note: this species seems to have many variations of sizes and ends

Scale bar = 10µm
species lacks a septa, capitate ends, round central area, contracts past the central broadens at the ends, striae are fine, parallel

sample from Sydney Diamond

note: first 2 specimens match Tabellaria flocculose var. linearis Koppen 1975; the last matches Tabellaria fenestrata--however, all of these forms appear in the Tabellaria fenenstrata page on Diatoms of North America

Scale bar = 10µm
larger valves are lanceolate/ clavate, broadly rounded footpole, narrow headpole, raphe is lateral, striae radiate, striae are broad, single stigma on one side in center

note: Diatoms of the North America reference shows different end shapes, more acutely rounded, than the Iowa specimens shown here

Scale bar = 10µm
valve is lunate in shape, the ends are rounded, there are small terminal nodes

note: This ID agrees with Patrick & Reimer, but species may grade into bilunaris---measurements also fit this species

Images of Eunotia bilunaris on Diatoms of North America have a wider central area making the morphology not exactly the same, the website's Illinois specimens of E. bilunaris may differ from Iowa specimens in this way

Burge, D, and Edlund, M. (2015). Eunotia bilunaris. In Diatoms of North America. Retrieved June 03, 2018, from https://diatoms.org/species/eunotia_bilunaris

Scale bar = 10 µm
appears to be similar to Stauroneis phoenicenteron but smaller, valves are linear lanceolate to elliptic lanceolate with rostrate, broadly rounded ends, raphe is lateral, raphe ends are hooked, striae are radiate, striae puncta are course