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WillmilneMay 22nd, 2009, 5:04 pm
Manitoba Canada

Posts: 19
Found a couple of S.xxxx nymphs

I think the first might be S. quebecensis

I'm not sure of the second one????

any suggestions?

TaxonMay 23rd, 2009, 7:42 am
Site Editor
Plano, TX

Posts: 1296
Hi Will-

Another possibility might be Siphlonurus phyllis, which I believe to be the only Siphlonurus species other than S. alternatus present in Manitoba.
Roger Rohrbeck
KonchuMay 23rd, 2009, 11:13 am
Site Editor

Posts: 496
what was the habitat for each one?
WillmilneMay 23rd, 2009, 2:06 pm
Manitoba Canada

Posts: 19
Habitat - silt/clay substrate /turbid large river - 400' wide / both from the same location at the river edge in approx 2' of water on the river side of small clumps of flooded grasses.

We have S.alternatus and S.phyllis listed here , but I get the sense we may have more here than the lists suggest.

I'm probably wrong on the first one . Ventral markings are a thin central dark stripe thinner at segment 1 than 9 - broken fine dark stripe at the outer edges of segments 1-9. approx 11-12mm

Number 2 is approx 14-15 mm with no discenrable marking on the ventral side.

Couple of larger images that may help. Since I like to photography these critters live and they rarely stay motionless some details may be blurred.


TaxonMay 23rd, 2009, 3:09 pm
Site Editor
Plano, TX

Posts: 1296

Your higher resolution photos both show "abdominal segments above marked with conspicuous branched pattern", and the 1st higher resolution photo shows "a prominent brown spot on each lateral margin midway between base and apex", which is described by Justin & Fannie Leonard on page 77 of their book, Mayflies of Michigan Trout Streams, as being characteristic of Siphlonurus alternatus.

Do you have a ventral photo of the sternite markings you described on the "first" one?
Roger Rohrbeck
KonchuMay 23rd, 2009, 4:05 pm
Site Editor

Posts: 496
keep in mind that several spp are unknown as nymphs
WillmilneMay 23rd, 2009, 5:07 pm
Manitoba Canada

Posts: 19
Roger- I will make some images on Monday of the ventral markings. Not sure if it means anything but over the period I was collecting on that day .Nymph 1 outnumbered nymph 2 by a ratio of approx 6:1

I did notice comparing the two images that nymph image 1 has lateral projections on segment 10 and nymph 2 does not the plot thickens:)

Konchu - I am new to all this but beginning to understand that your statement however frustrating is very true:))

Obviously I have been taking rather portrait/dorsal views of the nymphs I have been finding. It's becoming clear to me ( I bought Merrit and Cummins and have been rummaging around on Famu) that there must be a set views that would serve to document the salient details that would be of more use than simple portraits.

What would constitute a usefull set of nymph stage images ..


High magnification mouth parts

I know there are sampling protocols are there imaging protocols???


TaxonMay 23rd, 2009, 5:16 pm
Site Editor
Plano, TX

Posts: 1296

Please re-read my above post, which I was busy updating at the same time as your made your above post.
Roger Rohrbeck
WillmilneMay 25th, 2009, 12:30 pm
Manitoba Canada

Posts: 19
Thanks Roger-

Ventral view of Nymph 1 -

TaxonMay 25th, 2009, 1:47 pm
Site Editor
Plano, TX

Posts: 1296

Your ventral view of nymph 1 reveals markings extremely similar to those illustrated for Siphlonurus rapidus on page 79 of Mayflies by Knopp and Cormier.
Roger Rohrbeck

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