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3. Anyone know your western Drunella species?, Page 2

No one has mentioned size in these discussions. Is this not relevent?
In the central rockies I fish a size 10 for Grandis and a size 12 for Doddsi and a 14 for Flavilinea and they have to be that if you want to catch big trout. In the east the Lata is mostly a size 16 hook. Glacialis is apparently a size 8 to be fished properly although I have never fished this species.
That is my fly fishers take on Western Green Drakes.

No one has mentioned size in these discussions. Is this not relevent?
In the central rockies I fish a size 10 for Grandis and a size 12 for Doddsi and a 14 for Flavilinea and they have to be that if you want to catch big trout. In the east the Lata is mostly a size 16 hook. Glacialis is apparently a size 8 to be fished properly although I have never fished this species.
That is my fly fishers take on Western Green Drakes.

DD-

Yes, size does matter. :) However, as an aid to identification (or even imitation) it's just not as reliable or consistent as some fly-fishing texts would lead one to believe. For example, you mention that the Eastern lata that you see are about #16. On Pocono waters, the early lata that I so love to fish (the ones that used to be known as cornuta) are more like a #14, with many of the female duns closer to a standard #12. The later-hatching lata on those waters are about #16, or even #18. That's quite a range of sizes. It just goes to show why careful observation and local knowledge are so important.

By the way, how's the water down in your neck of the woods? It's been low for most of the season in much of the East, but I understand that the Southeast is in especially tough shape.

Best,
Gonzo

They weren't mentioned in this topic, but relative corpulence and silhouette are important (and the easiest) characters useful in telling doddsii apart from the grandis subspecies. Once becoming familiar with these critters streamside, they can be used to identify them at a glance in the adult stages. Though they all have stout thoraxes, it's the abdominal taper where the difference is most obvious. The grandis group (as with the flavilinea group on the other end of the size scale) has the more typical ephemerellid looking abrubt change in diameter from abdomen to thorax and the abdominal taper is much less dramatic where the first four segs are pretty close to the same diameter. With doddsii, the first segment of the abdomen is nearly as stout as the thorax with the rest tapering exaggeratedly to the terminal segs (check the ventral photo of this specimen).

Size is only reliable when compared against the other species groups in a particular watershed. D. doddsii always occupies the middle ground in my experience. This may mean size 12 in one location or a large 10 in another. I have not found characters like color, leg shape, or wing and tail length ratios to be reliable.

D. doddsii adults are perhaps one of the most misidentified species in photos on western flyshop websites (and even in some angler entomologies), which really adds to the confusion.

Nymphs are usually even easier to determine. Many seem to have trouble (probably due to lack of familiarity) and focus on frontal shelves and leg descriptions as provided in dichotomous keys. Others comment that they can't tell unless a ventral is provided showing a suction disk of circular hairs. It's easier than that because none of the large western species (or subs) of this genus are nearly as corpulent and lacking in tergal and head tubercles.