In North America there is only one genus and two species, thus making identification relatively easy. Species of Ammophilus are unusual among mayflies in that they occur in sandy substrates.

Ametropus ammophilus Allen

Type Locale: Washington

California Distribution: El Dorado, Humboldt

Adult Description: Allen and Edmunds (1976) described this species, including a key to North American Ametropus and a figure of the male genitalia (Fig. 4) and wings (Fig. 6).

Larval description: Allen and Edmunds (1976) described the larvae, including a complete dorsal view (Fig. 2). There is no key to larvae, and so one will rely on the figure and descriptions provided by Allen and Edmunds (1976).

Identification Notes: Because of the distinctively long claws, A. ammophilus may superficially resemble long-clawed baetids (e.g., Procloeon spp), but the short antennae and lack of labral notch help easily distinguish this species from the long-clawed Baetidae. More detail on the taxonomic history of the genus in North America can be found in McCafferty (2001) and Jacobus (2013).

Ecological notes: Allen (1977) reported collecting larvae of this species from the Upper Truckee River in the southern portion of the Lake Tahoe Basin. Allen and Edmunds (1976) reported this species restricted to sandy substrates. They also reported this species preferring moderate to large rivers between 400-3700ft elevation. The Upper Truckee does not fit this profile, however. This is a higher elevation and relatively small stream. The Klamath in Humboldt County is a larger body of water, and so the type of habitat this species occurs may be more variable than reported in the literature.

References:

Allen, R. K. and G. F. Edmunds, Jr. 1976. A revision of the genus Ametropus in North America (Ephemeroptera: Ametropodidae). J. Kansas Entomol. Soc. 49: 625- 635.

Jacobus, L. 2013. A new junior synonym for the Holarctic species Ametropus fragilis Albarda, 1878 (Insecta: Ephemeroptera: Ametropodidae). Proceedings Indiana Acad. Sci. 122: 18-19.

McCafferty, W. P. 2001. Commentary on Ametropus species (Ephemeroptera:            Ametropodidae) in North America. Great Lakes Entomol. 34: 1-6.