laneallen's Identifications

Mag. 400x

• A pond-side water sample (retentate) was taken on 01/06/2024 using a 10µ dip net to enrich for microorganisms. (The shoreline had a layer of ice about 1/4" thick that needed to be breached in order to accommodate the dipnet. The retentate contained a lot of sediment due to the shallow depth and disturbance caused by the net.) Air temp 35F. (sample has been sitting on a cool, west-facing window ledge since 1/6/24)

Large Stauroneis specimen (200µ L x 45µ W; L/W = 4.44). The stauros (clear, transverse band in the central area) is rectangular rather than bowtie-shaped. The striae are slightly radiate and densely packed at 12 striae per 10µ near the central region (see image 2). Proximal termini of the raphe are expanded (looking like the end of a Q-tip) and, to my wishful eye, the terminal portion of each proximal raphe is slightly deflected up, toward the top of the photos in image 1 (perpendicular to the long axis). These characteristics and the overall shape and size correspond well with the taxon, Stauroneis americana as seen here https://diatoms.org/species/stauroneis_americana.