» Genus Ameletus (Brown Duns)
25 species aren't included.
This is page 2 of specimens of Ameletus. Visit the main Ameletus page for:
- The behavior and habitat of Ameletus.
Pictures of 21 Mayfly Specimens in the Genus Ameletus:
Ameletus (Brown Duns) Mayfly Nymph
View 7 PicturesI think this is a pretty early instar (Instar: Many invertebrates molt through dozens of progressively larger and better-developed stages as they grow. Each of these stages is known as an instar. Hard-bodied nymphs typically molt through more instars than soft-bodied larvae.) Ameletus nymph. It's certainly a striking one. Ameletus vernalis (Brown Dun) Mayfly Nymph
View 9 PicturesI keyed this one out using the Alberta species key from Zloty & Pritchard 1997.
Notes from the ID include:
1. Posterior (Posterior: Toward the back of an organism's body. The phrase "posterior to" means "in back of.") margin of sternites (Sternite: The bottom (ventral) part of a single segment on an insect's abdomen.) 6-8 without spines
2. Mesal (Mesal: Toward the middle.) gill extension "well developed"
3. Basil third of caudal (Caudal: Toward the posterior tip of the body.) filaments pale
4. Anterior (Anterior: Toward the front of an organism's body. The phrase "anterior to" means "in front of.") surface of front femora (Femur: The main segment of an insect's leg close to the body, in between the tibia and the trochanter.) mostly pale
5. Dark band on caudal (Caudal: Toward the posterior tip of the body.) filaments begins around segment 20
6. Final instars (Instar: Many invertebrates molt through dozens of progressively larger and better-developed stages as they grow. Each of these stages is known as an instar. Hard-bodied nymphs typically molt through more instars than soft-bodied larvae.) early season
This one keys out pretty cleanly to Ameletus vernalis except the color pattern on the tergites (Tergite: The top (dorsal) part of a single segment on an insect's abdomen when it consists of a single chitinous plate (sclerite), or an individual sclerite if the segment has more than one.) doesn't match. However, two species known in Washington aren't included in the key. Of those two, Ameletus vancouverensis would be too small (adult body length 9 mm), but Ameletus andersoni (currently documented only from a spring in Cowlitz County) has a wide range of sizes and emergence times that could be compatible with this one. So I can't rule that species out, but Ameletus vernalis seems the most likely.
Female Ameletus (Brown Duns) Mayfly Spinner
View 13 PicturesI found this female already spent (Spent: The wing position of many aquatic insects when they fall on the water after mating. The wings of both sides lay flat on the water. The word may be used to describe insects with their wings in that position, as well as the position itself.) and nearly dead, laying in the surface film of a very tiny spring seep (inch-deep water) in the valley of a very small trout stream.