Revision of North American Hyalomyzus

Hyalomyzus is one of many genera that were split from Myzus during the 20th century. It was originally used for a few American species, but eventually expanded to include a few Indian forms as well. Several recent papers have discussed the genus, making it one of the better understood North American aphid genera. Yet we knew that putting all available information on this genus and its species into one place would be valuable, and would make identification of the species less confusing. This fact, in addition to the ready availability in the field of some species of the genus made us decide to revise the group.

We hoped to accomplish the following with this work:

Analyse all available material of Hyalomyzus in an attempt to confirm or deny the validity of the described North American species;
Provide a better understanding of the life histories of the species feeding on apple (Malus spp.) and hawthorn (Crataegus spp.) in eastern North and Central America;
Perform the first cladistic analysis of the genus.

You may view a PDF copy of our publication, Reevaluation of the Genus Hyalomyzus Richards... , to read about the results of our work in its entirety.

Species of Hyalomyzus

At the beginning of this study, there were 8 species of Hyalomyzus recognized as valid in North America. Our study reports on 9 North American species of the genus, including two new species and the synonymy of one species from Florida. We also clarified the status of two of the species, which had been confused in the literature. For example, Nielsson and Habeck (1971) had treated Hyalomyzus sensoriatus, including in the species all the material from the original description by Mason (1940) (on Crataegus) as well as specimens from Pennsylvannia (on Hypericum). Our analysis showed that Mason's original material was a mixture of Hyalomyzus eriobotryae and H. sensoriatus and that the material from Pennsylvannia was in fact the species described by Smith (1982) as Hyalomyzus mitchellensis. The picture on the right illustrates a generalized winged and wingless Hyalomyzus adult female. A generalized Hyalomyzus, left side wingless, right side winged.

Life history of a new species, Hyalomyzus pocosinus Stoetzel, Jensen and Miller

Most species of Hyalomyzus live during the summer in wet, marshy habitats, and we were able to study three species in the area of Beltsville, MD. One of these was a new species. The new species is named Hyalomyzus pocosinus and was found feeding on the lower stems and roots of a semiaquatic herb called Triadenum virginicum (formerly in the genus Hypericum). The name pocosinus comes from the Algonquian (Delaware) word meaning "shallow place" and referes to the swampy or boggy habitat of this aphid. The top picture at right is the habitat in which we found this species. The illustration below this shows various structures that are helpful for identification and comparing this species to other species of Hyalomyzus. Hyalomyzus pocosinus is unique among all other species of Hyalomyzus because of the different type of sculpturing found on the head, the number of setae found in various regions of the body, the length of its mouthparts, and the number of veins on the hind wing of the winged adult females. The adult males are wingless.
Hyalomyzus pocosinus lives throughout the year on T. virginicum. It is usually found on plants growing atop grassy hummocks. Eggs are laid near the base of the plant on the stem or roots. We were not able to determine whether eggs that are submerged by high water during the winter are able to survive.
Habitat of two species of Hyalomyzus Head, antennae, cornicle, and cauda of Hyalomyzus pocosinus

References

Mason, P. W. 1940. A revision of the North American aphids of the genus Myzus. U. S. Dept. Agr. Misc. Publ. 371: 1-30.
Nielsson, R. J., and D. H. Habeck. 1971. The genus Hyalomyzus (Homoptera: Aphididae), with the description of a new species. Ann. Entomol. Soc. Am. 64: 883-887.
Smith, C. F. 1982. A key to the species in Hyalomyzus (Homoptera: Aphididae) in North America, with the description of a new species. Proc. Entomol. Soc. Wash. 84: 325-331.
Stoetzel, M. B., A. S. Jensen, and G. L. Miller. 1999. Reevaluation of the genus Hyalomyzus Richards with the description of two new species (Homoptera: Aphididae). Ann. Entomol. Soc. Am. 92: 488-513.

Last Updated: September 1, 1999