This is a terribly complex genus with many interesting species in North America. A very nice revision was done by Heie (1979), which gathered a lot of information and specimens from all over the world. He also established a nice subgeneric classification. His work was hampered somewhat by relatively little material from western North America, especially of the subgenus Kakimia. As I travel around collecting Nasonovia (Kakimia) aphids, the species-level taxonomy gets more and more opaque. More specimens of this group has for me equated with less clarity about species boundaries to the point that in many cases I simply put the name ‘Kakimia‘ on slides and leave it at that. Much additional field and lab work will be required to get a handle on the full range of Kakimia diversity in North America. I hope to post some photos of some ‘species’ and comment further on this overall situation.
Nasonovia (Kakimia) aquilegiae (Essig)
This is a very common species across much of North America on Aquilegia (columbines). It lives on both ornamental plants as well as native Aquilegia in the mountains. It is distinctive for its dorsal pigmentation in the apterae and for its dedication to its Aquilegia hosts. I often walk by this species in the field because it is so common and easy to recognize, but I so far have material from Washington, Oregon, Idaho, and Maryland.
Nasonovia (Kakimia) arizonensis Heie
I have seen what I think is this species quite a few times now across the western U.S. It was originally described from Arizona, which is thought of as a desert state, but there are plenty of forests there like the one from which the type collection was made. I collect this species on Ribes cereum from the sagebrush steppe to dry mountain slopes. It causes a strong leaf curl, and is often on the same plants with Nasonovia (Kakimia) houghtonensis group aphids and Aphis (Bursaphis). I have material from Idaho, Washington, and Utah.
Nasonovia (Capitosiphon) crenicorna Smith and Knowlton
I started collecting fervently on wild geraniums a bunch of years ago because I wanted to find Macrosiphum species that feed on these plants. Instead, mostly what I find throughout the interior mountains of the west is N. crenicorna. It is very common on Geranium richardsonii and what I think is Geranium viscosissimum (turns out the two plants are very similar). It has an early sexual cycle, in July and August, mainly because the Geranium host plants are finishing up their life cycles at that time. I have material from Idaho, Utah, and Wyoming.
Nasonovia (Kakimia) houghtonensis (Troop)
This is a very interesting and complex taxon, currently represented as five subspecies, a system boldly and courageously established by Heie in 1979.
I have never been much for subspecies — in my collection and my thinking either something is a species or it isn’t and I try to have fairly strict standards on the issue. The subspecies discussed by Heie seem to have different life cycles and perhaps host plant biologies. I agree that there are several probable life cycles among the samples I have collected, but I suspect adequate characterization would reveal full, reproductively isolated species. Perhaps Heie’s intent with the subspecies was to draw attention to this issue.
An enigmatic member of this probable species group is one that seems to migrate to Phlox speciosa as a secondary host. I have collected it here and there for several years, but have yet to make a firm connection between aphids on Phlox and any of the many “houghtonensis” group samples from Ribes. The seasonal timing of my samples from Phlox strongly suggest host alternation, but as of now the host alternation is unproven. I have this Phlox-inhabiting form from Washington in several places and from west-central Idaho. My samples of the broader Nasonovia (Kakimia) houghtonensis group are from British Columbia, Alberta, Washington, Oregon, Idaho, Utah, New Mexico, and Arizona.
Nasonovia ribisnigri (Mosley)
This is the only Nasonovia sensu stricto known from North America, and is apparently introduced here. It is heteroecous between Ribes and various plants in Europe, especially hairy ones, but I find it on Asteraceae. I so far have material from Germany, Switzerland, Czech Republic, Washington, Oregon, Idaho, New Hampshire, and New Brunswick.
Nasonovia (Aconitaphis) wahinkae (Hottes)
I find this aphid on Aconitum (monkshood) in the Rocky Mountains and interior mountains of the west, so far in Colorado, Utah, Idaho, and Oregon. It is one of a few aphid species that I know of now that come in both a bright orange form and the darker green-brown-purple form (it can also be green). It can form very dense populations on its plants, but I also routinely find it in small numbers on the lower leaves.
Nasonovia (Kakimia) williamsi (Smith and Parron)
This species seems to live without host alternation on Potentilla in western North America. I walk past Potentilla on almost every collecting trip in natural systems out west, yet have only collected this aphid twice. If memory serves me correctly, I might have seen it a time or two in which I did not collect it for some reason. The leaf curl it causes is conspicuous, making its presence easy to notice. From this experience, I conclude that this species in rather rare.