Apodemia mormo cythera

Cythera Metalmark

There is a remarkable population of "mormon metalmarks" that fly in a single brood ca. late July into September on the northern side of the San Gabriels; they are easily found taking nectar on rabbitbrush up Big Rock Creek Road. This is the golden-orange cythera, a truly beautiful butterfly that is starkly different from either nominate mormo or virgulti. In this large creek area, the common buckwheat is Eriogonum heermannii, the larval food plant of this population. I soon found this butterfly up at Mt. Islip to the south around fasciculatum, and at Grizzly Flat as well, all in the same general part of the San Gabriels. Some thirty air miles east at Mojave River Forks, a similarly orange fall-flying mormo cythera, on Eriogonum fasciculatum and E. wrightii, may be found. These populations along the desert edge foothills of the San Gabriels and western San Bernardinos are the southernmost cythera. To the north, they range along the eastern side of the Sierra Nevada, and into the Death Valley and vicinity ranges (Coso, Argus, Panamint, Inyo, etc.). In this northern part of the range, they may use the buckwheats E. umbellatum and E. microthecum as well as fasciculatum.

The relation of cythera to tuolumnensis is puzzling. The latter may or may not be restricted to the Hetch Hetchy dam area, the type locality. The type locality of cythera is "Arizona" in the original description from 1873, but in all likelihood the collectors were around Lone Pine in Inyo County, not in Arizona. If cythera ranges south as far as the transverse ranges, perhaps that is what is blending with the very dark mormo to the northeast of Big Bear. Yet John Emmel was calling the fall flyers from east of Van Dusen Road "near tuolumnensis for want of a better name" in 2017 (via email). What are the light autumn fliers to the west in L.A., Ventura, Santa Barbara, San Luis Obispo, and Kern counties? To Ken Davenport, these are tuolumnensis (Emmel Update). Clearly, there is work to be done on these, and wing characters alone are insufficient to sort out what is what. Restricting the range of tuolumnensis to what it was originally opens up the possibility that the subspecies name cethura would cover light western populations, leaving (subspecies) mormo and perhaps autumnalis to cover most dark members of this species to the east. But what will the results of thorough DNA testing suggest?

Apodemia mormo cythera from Big Rock Creek, on the northern side of the San Gabriels. Note the extensive yellow on the hind wing. July 29, 2009.
Apodemia mormo cythera - Cythera Mormon Metalmark
A ventral of Apodemia mormo cythera from Big Rock Creek. July 29, 2009.
I revisited Big Rock Creek on August 17, 2010 and again found Apodemia mormo cythera in good numbers on the rabbitbrush. For those used to seeing the very common, widespread virgulti or the dark varieties of mormo, seeing these much more golden yellow cythera from this location should be a treat. When fresh, they really are striking.
Apodemia mormo cythera - Cythera Mormon Metalmark
Another ventral, same day as above. These single-brooded butterflies are easily found in late summer and/or early fall up Big Rock Creek Road where rabbitbrush is blooming. The caterpillars will do some of their feeding next year in the early summer when the buckwheat flowers are in bloom.
Apodemia mormo cythera from Mojave River Forks
Apodemia mormo cythera from Mojave River Forks, about 30 miles east of the above population. These have an interesting phenotype, with small white macules and extensive dark orange coloration. Sept. 6, 2007. They fly only in the late summer/early fall, and the buckwheat hosts are E. fasciculatum.
Apodemia mormo cythera - Cythera Mormon Metalmark
Apodemia mormo cythera from below Mt. Islip in a patch of E. fasciculatum at approx 6790' elevation. The phenotype is close to what one sees a few miles downhill to the north in Big Rock Creek (4-5000' elev.), where the mormo cythera are almost yellow.

©Dennis Walker