Around 2003 I did see a report of Anthopotamus from California on a poster presentation of aquatic insects from the Lake Tahoe Basin, and originally I was doubtful this was correct until I saw the report from McCafferty and Meyers (2007). In North America the Potamanthidae are an eastern group, and I believed this specimen was mistaken for a tusked Paraleptophlebia. There is a PhD dissertation by Panayotou, “Aquatic Insects in Tahoe basin streams: the link between stream restoration and biological assessment” (Panayotou 2003), but this genus was not reported in that work.

The specimen identified by McCafferty and Meyers (2007) was deposited in the Illinois Natural History Survey and later identified by McCafferrty and Meyers (2007). The locale data are problematic, however. I believe the location on the label, Upper Truckee R at Rt 299,  is a mistake as there is no Rt 299 in that part of California. It is possible this label is actually referring to State Hwy 89. There are GPS coordinates listed as part of the accession record (one can find this in the Illinois Natural History Survey online database), but these seem to have been added later, not when the specimen was collected (the GPS coordinates point to the mouth of the Upper Truckee, where it empties into Lake Tahoe–there is no road access here). I have collected this stream off Hwy 50 (not that far from any HWY 89 location) and have found tusked Paraleptophlebia, but not Anthopotamus. I plan to keep looking.

Anthopotamus verticis (Say)

Type Locale: Indiana

California Distribution: El Dorado Co.

Adult Description: The best key and descriptions for the genus was that done by Bae and McCafferty (1991). This is one of those rare mayfly groups that one can identify female adults to species. I would add to Bae and McCafferty’s (1991) key that the apex of the foretibia has dark markings. This is true at least for many mid-western specimens I have looked at.

Larval description: As with the adults, the best key and descriptions for the genus was that done by Bae and McCafferty (1991). A complete description is provided as well as figures of the tusks (Figs. 33 and 34)..

Identification Notes: This is one of the few tusked mayflies known in California, and may superficially resembled some of the tusked Paraleptophlebia species (P. helena, P. bicornuta etc), which are much more common in the state.

Ecological notes: Bae and McCafferty (1994) did an analysis of the microhabitat of this species in Indiana. One finds this species in gravel or pebbles, which does fit habitat one can find in the Upper Truckee River (and many Sierra streams, actually). They described this species as “crude burrowers”.

References:

Bae, Y. J. and McCafferty, W. P. 1991. Phylogenetic systematics of the Potamanthidae (Ephemeroptera). Trans. Amer. Entomol. Soc. 117: 1-143.

Bae, Y. J. and McCafferty, W. P. 1994. Microhabitat of Anthopotamus verticis (Ephemeroptera: Potamanthidae). Hydrobiologia 288: 65-78.

McCafferty, W. P. and M. Meyers. 2007. An extreme range extension and disjunction for the Ephemeroptera Family Potamanthidae in North America. Proc. Entomol. Soc. Wash. 109: 737-738.

Traver, J. R. 1935. Part II. Systematic. Pp. 237-739 in The Biology of Mayflies by Needham, J.G., J. R. Traver, and Y.-C. Hsu. Comstock Publishing Company, Inc. Ithaca.

Panayotou, D. 2003. Aquatic insects in Tahoe basin streams: the link between stream restoration and biological assessment. Ph.D. University of California, Davis.