Some results from a special trip to Lemsford Ferry in August 2009.
The South Saskatchewan River at Lemsford Ferry, near the Alberta border (site B on the map half way to the bottom of HOME), is little impacted by dams, pulp mills, sewage, or effleuents, and I find that it is unique in the Saskatchewan River system. It seems to be unique in the world. It has has a very diverse mayfly community that is not only a large number of species present, but also found are very unusual, rare,or otherwise unique species. Many are shared with the Colorado River system, some are eastern or mountain species, and the combination unusual.
Found here are species of the genera Ametropus, Lachlania, Isonychia, Raptoheptagenia, Macdunnoa,Traverella, Choroterpes, Acanthamola, and probably Pseudiron and Analetris. Also present are the more common genera Ephoron, Heptagenia, Stenonema, Stenacron, many genera of Baetidae, plus Tricorythidae, and others.
Here I give information, photos, and videos on Lachlania, Raptoheptagenia, and Traverella. See videos for Isonychia.
Views, Lemsford Ferrry, South Saskatchewan River, Sask. nnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnn
Three inches of rain had fallen in the past few days, water temperture 66 F, overnight air temperature 48 F. August 16, 2009.
This photo at Lemsford Ferry is from the north ferry ramp, the south ferry ramp can be seen across the river, and turbulence on the water surface shows the very rapid current in mid river. Slower current is found near shore, the gravel and rubble substrate can be seen. A calm backwater deposition zone is to the left. Rains have caused a moderate sediment load in the water. A few stalks of aquatic vegetation break the surface in the foreground. Many species are restricted to limited sites, in terms of current speed, substrate , and water depth, and the proper site must be sampled to collect them. .
Raptoheptagenia cruentata Whiting and Lehmkuhl, From my field notes and collections, I first collected larvae this species on 12 July, 1970, at Lemsford Ferry. Two specimens were collected, 7 and 11 mm long respectively. They were taken to the laboratory alive, and they readily fed on Chironomids held in forceps. Additional specimens were collected at Lemsford Ferry on 21 June 1971. They were found in fast water with a rubble bottom. Sizes were 7 mm-2 specimens, 8 mm- 1 specimen, 9 mm- 1 specimen, 11 mm- 2 specimens. In the lab they held on to stones and bark, they avoided sand, and they were very awkward swimmers. I reported them in Lehmkuhl (1976) as Anepeorus rusticus McDunnough- according to the literature and references of the time. Later, larvae were reared to adults, a new genus was described by us, and the new correct name is as above. See Home for link to original paper. Larvae were collected at various times in subsequent years.
Above,Living R. cruentata from below, especially to view the abdominal gills.
Video- Larvae of Raptoheptagenia are awkward swimmers and not active; gills are not active.
The character of Lachlania saskatchewanensis can be seen in the video below. Larvae are strong and heavy bodied. Setae on the front legs filter particles from the water, and the posterior 4 legs grasp substrates such as willow roots. See Rare Species for extensive information
For drawings, keys, and descriptions of the larvae of Traverella, see Richard K. Allen, 1973, Traverella in North and Central America,- go to :
http://www.famu.org/mayfly/mfbib_a.php to get a pdf of the paper. . The prognathous mouthparts, with quadrate labrum, labium, and maxillary palps, plus large (and active) gills are characters which separate this genus from other Leptophlebiidae. See Ephemeroptera for discussion and classification.