Ephemeroptera - mayflies

Intro(from Merritt and Cummins)

http://www.entomology.umn.edu/midge/VSMIVP%20Key/English/VSMIVP.htm

Lotic and lentic

• Highest diversity in rocky-bottom, 2nd and 3rd order headwater streams

• Information primarily from larvae - why?

Repro?

• Eggs laid at surface

• In some (Baetis), females crawl under water and lay eggs on stems

Eggs hatch in 3 - 9 months

• Larval life ~ 3-6 months – Hexagenia in Lake Winnipeg = 1-2 years

• Many molts (12 - 30)

Collectors or scrapers usually

• Detritus, algae, macrophytes, etc.• Few carnivores• Usually shift diet with size

• Subimago (winged, sexually immature form)

Mating

• Males usually emerge after dusk, females shortly before dawn

• Mating swarms

Morphology of larvae

• Large eyes, outer position• Antennae anterior or ventral

to eyes• Mouthparts:

Thorax

• Wingpads: on meso- and metathorax

• Pair of legs on each thoracic segment

Abdomen

• 10-segmented

• Gills usually on abdomen

• 3 caudal filaments usually

Adult mayfly

• Males have large eyes

You will need to be comfortable with key to family• 13 families:• Baetiscidae, Potamanthidae,

Ephemeridae, Polymitarcyidae, Tricorythidae, Caenidae, Ephemerellidae, Heptageniidae, etc.

• http://www.entomology.umn.edu/midge/VSMIVP%20Key/English/VSMIVP.htm

Ephemeroptera key

• Baetiscidae = large thoracic notum

• Armored mayflies

Mandibular tusks?• Yes? Abdominal gills held laterally =

Potamanthidae = hacklegill mayflies

Mandibular tusks?• Yes, pointed upward,

abdominal gills held dorsally = Ephemeridae

• Common burrowing mayflies

Mandibular tusks?• Yes, project downward, abdominal gills

held dorsally = Polymitarcyidae• Pale burrowing mayflies

No mandibular tusks?

• Abdominal gills on segment 2 plate-like, operculate, triangular = Tricorythidae

• Little stout crawler mayflies

No mandibular tusks?• Abdominal gills on segment 2 plate-like,

operculate, square = Caenidae • Small square-gill mayflies

No mandibular tusks?• Abdominal gills on segment 2 similar to

other gills if present, or gills operculate and no gills on segment 2 = Ephemerellidae = spiny crawler mayflies

No mandibular tusks?

• Abdominal gills on segment 2 similar to other gills if present, or gills operculate

• gills present on segments 1-7 or 2-7• Flattened head and body =

Heptageniidae = flathead mayflies

No mandibular tusks?• Abdominal gills on segment 2 similar to

other gills if present, or gills operculate• gills present on segments 1-7 or 2-7• Head and body not flat• Abdominal gills forked = Leptophlebiidae• Prong-gilled mayflies

Same characters as last slide:Head and body not flatGills oval or heart-shapeForeleg claws forked = MetretopodidaeCleft-footed minnow mayflies

Same characters as last slide:

• Head and body not flat• Gills oval or heart-shape• Foreleg claws simple• Long setae on inner fore legs =

Isonychiidae = brush-legged mayflies

Same characters as last slide:

• Head and body not flat• Gills oval or heart-shape• Foreleg claws simple• No long setae on inner fore legs • Labrum w/deep notch = Baetidae• Small minnow mayflies

Same characters:• Head and body not flat• Gills oval or heart-shape• Foreleg claws simple• No long setae on inner fore legs, spine • Labrum entire = Siphlonuridae• Primitive minnow mayflies

Today:

Get comfortable with all mayfly families = run them through key