Click on thumbnails for expanded image; more to follow each month this winter (03-04) . . .
Peridinium willei; widespread and occasionally common in samples (this species and P. gatunense are the most likely suspects should you encounter a relatively large, lumpy, and otherwise non-descript brown Dino in your sample; note the flange and LACK of a distinct apical pore.
Peridinium volzii; VERY similar to willei but lacks that apical flange; rarely encountered by us but a tricky ID by light microscopy. Also refer to th similar P. bipes which differs most markedly in having an obvious apical pore.
Peridinium limbatum; our first encounter with this large and very distinctive species in the wild; however the species may be a locally common component of lake plankton in the northeastern USA. The cyst forming in photos 4 & 5 is especially noteworthy. Note the flagellum in photo 6
Peridiniopsis penardiforme; at first glance may appear as yet another blob on your slide; but note the deep cingulum, apical pore, and in side view, strong dorso-ventral flattening (a unique set of features); the species is fairly common and widespread in eastern USA lake samples.
Peridinium inconspicuum; as the name implies this tiny species goes un-noticed by most observers yet it is a very widespread and common component of lake algae. Shape varies somewhat, a point that still confuses us at times, however, a thecate (armored) Dino cell roughly 12 x 14 microns, golden in color, and the shape of a house, is almost certainly P.inconspicuum.
A rare treat - only the 2nd time Susan has photographed this species in 20 years of collecting.
Peridiniopsis quadridens & P. cunningtoni; AT LEFT a rotund cell, a feature distinguishing it from the very simlar congeneric relative AT RIGHT P. cunningtoni which is strongly dorso-ventrally flattened reminiscient of the "potato flake" P. polonicum. The resemblance is also strong in full ventral view as seen here. The latter is more refined over its more robust cousin, a consequence of which are distinct swimming styles with the sleek torpedo movements of cunningtoni contrasting with the dodgy ramblings of quadridens. All three are moderately common although the very distinctive polonicum is much more widespread and can occur in bloom conditions. Perhaps a trickier ID is separating quadridens from the equally rotund and moderately common Peridinium aciculiferum. However, note the positioning of the spines. The degree of ornamentation can vary among all these species, however, when the spines protrude mid-plate you are dealing with Peridiniopsis, whereas spines in Peridinium protrude along the plate sutures.
Peridinium wisconsinense; this unique looking Dinoflagellate is infrequently encountered by us but may be more frequent in brown water lakes to the north and east of Ohio. May be locally common in the Upper Peninsula of Michigan for example.
We add to our existing images of the species with this apparent cyst forming.
Prize of the Season
This Ceratium carolinianum , from the U.P. of Michigan, was the first of the species Susan had found since recording it in Texas 20 years ago. Note the tiny Peridinium inconspicuum attached to the tip of the ant-apical horn. Scroll down for some light micrographs of this rare Ceratium.
A dorsal view of Peridinium limbatum to supplement the ventral view on the main page.
This Woloszynskia coronata is one of few detected in SEM samples. Yet this remains the best means by which to come to a conclusive identification. It is only in such views that the polygonal nature of the plates becomes clear. Ignoring the membranous tatters coating this particular cell, note the shape of the many smaller plates that characterizes members of this genus. W. coronata has been confirmed by us perhaps 10 occasions in a fairly widespread distribution. Given the difficulties in identification, and the equal number of samples where we suspect this species, it is likely the more numerous member of the genus found in eastern U.S. fresh waters. The very distinctive (identifiable by light microscopy) W. tylota and W. reticulata by contrast have been rarely encountered by us.
