Alex Wild includes images of three species of Myrmecocystus with reddish-orange heads and black abdomens (gasters) on his website: M. depilis (Portal, AZ), M. mendax (Chiricahua Mts, AZ), and M. mimicus (Sycamore Cyn, AZ). The latter species also occurs at Carrizo Plain National Monument, CA and Green Valley, AZ. The three species superficially resemble the following images of honeypot ants I observed north of Salton Sea State Park.

Myrmecocystus mexicanus has been reported from the Salton Sea, but this species has an amber-colored head and body. It has also been reported from 5,185 ft Keys View (Salton View Overlook) in nearby Joshua Tree National Park. Alex Wild includes images of this species from the Mojave Desert, CA plus images of two additional amber-colored species: M. navajo (Wilcox, AZ) and M. testaceus (Mojave Desert, CA). He also includes another species from sand dune areas of the Mojave Desert with a black head and body (M. tenuinodis). I have photographed M. mexicanus (or M. navajo) from Holbrook, AZ.

Based upon Antwiki Myrmecocystus Species Groups and Antwiki Key To Myrmecocystus Species (Both Accessed 8 February 2015) this species belongs to the Mimicus Group in the subgenus Endiodioctes:

These are medium-sized species in which the head and thorax of the worker are extensively brownish, the frons and occiput are smooth and shiny and the third tergum is without conspicuous appressed pubescence. The malar area has few or no erect hairs. This group ranges from Trans-Pecos Texas to California and south to central Mexico. The two species appear to be largely scavengers and also gather large quantities of nectar and honeydew; repletes are known for both. These are primarily lowland species, but follow alluvial fans onto the lower slopes of desert mountain ranges. Nests are often situated at the base of a shrub or amidst a clump of grasses. Tumuli thus are often somewhat irregular. When nests are located in open areas, the tumulus is most often a low, broad, regular crater.

I decided to compare the species of Myrmecocystus north of the Salton Sea with another species from the mouth of Cave Creek Canyon (Chiricahua Mtns) near Portal, Arizona. The Portal species is larger, has a darker head (not as reddish), and has more erect hairs in malar area and on head. In my opinion, it does not appear to be abundantly hairy (densely pubescent) as reported in Antwiki for the Melliger Group (including M. melliger, M. mendax and M. placodops). They are all active predators and scavengers, especially on other arthropods. In my pitfall trap several of these Portal species attacked a solpugid (see following image). M. mendax has been reported from Portal, along with M. placodops. M. melliger is reported from Cave Creek.

In conclusion, I am uncertain about the common bicolored Myrmecocystus (subgenus Endiodioctes) ants north of the Salton Sea. There may be more than one species. Myrmecocystus mimicus is common in southern California and this may be that species; however, the very similar M. flaviceps has been reported from this area. I have one photo of a honeypot ant from Box Canyon North of Mecca and the Salton sea that appears to be M. flaviceps. Tergum III has densely appressed hairs and the gaster is dull black compared with the glossy black gaster of M mimicus. M. flaviceps has been reported from Mecca, North of the Salton Sea, Joshua Tree National Park (Cottonwood Campground), Deep Canyon near Palm Desert, and the Algodones Dunes!