Great Basin Naturalist Volume 38 Number 4 Article 2 12-31-1978 Mountain ants of Nevada George C. Wheeler Adjunct Research Associate, Desert Research Institute, Reno, Nevada Jeanette Wheeler Adjunct Research Associate, Desert Research Institute, Reno, Nevada Follow this and additional works at: https://scholarsarchive.byu.edu/gbn Recommended Citation Wheeler, George C. and Wheeler, Jeanette (1978) "Mountain ants of Nevada," Great Basin Naturalist: Vol. 38 : No. 4 , Article 2. Available at: https://scholarsarchive.byu.edu/gbn/vol38/iss4/2 This Article is brought to you for free and open access by the Western North American Naturalist Publications at BYU ScholarsArchive. It has been accepted for inclusion in Great Basin Naturalist by an authorized editor of BYU ScholarsArchive. For more information, please contact [email protected], [email protected]. MOUNTAIN ANTS OF NEVADA George C. Wheeler' and Jeanette Wheeler' Abstract.- Introductory topics include "The High Altitude Environment," "Ants Recorded from High Alti- tudes," "Adaptations of Ants," "Mountain Ants of North America," and "The Mountains of Nevada." A Nevada mountain ant species is defined as one that inhabits the Coniferous Forest Biome or Alpine Biome or the ecotone between them. A table gives a taxonomic list of the mountain ants and shows the biomes in which they occur; it also indicates whether they occur in lower biomes. This list comprises 50 species, which is 28 percent of the ant fauna we have found in Nevada. Only 30 species (17 percent of the fauna) are exclusively montane; these are in the genera Mymiica, Manica, Stenamma, Leptothorax, Camponottis, Lasiiis, and Formica. The article concludes with "Records for Nevada Mountain Ants." All known records for each species are cited. For each record we give first the county, next the mountain range, then the peak (or other local feature), and finally the elevation. Epigraphs Biome (BMS74- 13679). For this study we hired Alvin McLane (one of Nevada's most "The first compilation of world ants experienced mountaineers) and Jane Ram- found at elevations of 2000 m (6560 ft) or burg (a senior botany major at Wellesley more shows that, while many species may College) for two months during the summer be found at the 2000 m level, the numbers of 1975. The second grant (DEB76-11131) decrease rapidly with increase in altitude. was for the upper levels of the Coniferous ants are found at Few 3000 m (9840 ft), Forest Biome. For this study we hired two and at 4000 m (13,129 ft) or more only nine University of Nevada, Reno, students, Gary species are known. The world altitudinal re- Nigro (a graduate entomology student) and cord is of Formica picea lockmatteri Stiircke Wendy Guyer (a senior botany major) for at 4800 m. (15,740 ft) in the Himalayas" two months during the summer of 1977. (Weber 1943: 351). The above should not be taken to mean "While other branches of entomology that we have had no personal experience have great made advances in recent years, with high-altitude ants. We have taken ad- our insect knowledge of the life of the vantage of the excellent gravel road up to North American mountains is, however, ex- 12,000 ft on Mt. Grant (elevation 12,200 ft) tremely fragmentary" (Mani 1968: 365). near Hawthorne and a passable road up to 10,000 ft on Mount Jefferson (elevation Acknowledgments 11,949 ft). There are also many roads up to 9000 ft, but these one-lane roads without As soon as we moved to Nevada in 1967 turnouts generally lead to mines. we began a study of the ants of the state. We thank Alvin McLane for reading the Most areas were readily accessible, thanks manuscript. to an excellent highway system and a Jeep Wagoneer. But we soon found that we were Definition too old for hiking and backpacking in the rarified air of the mountaintops. In his book, Mani (1968:8) preferred the To remedy this handicap, we applied for term "hypsobiont" or "high altitude" to "al- and were awarded two National Science pine" and gives this definition: "The high Foundation grants to employ students to altitude insects may thus be described as an collect for us. The first was for the Alpine ecologically highly specialized, mountain 'Adjunct Research Associates, Desert Research Institute, Reno, Nevada 379 380 Great Basin Naturalist Vol. 38, No. 4 autochthonous group existing exclusively in 3. Atmospheric aridity. the biome above the forest, at elevations 4. Intense solar radiation. "Regardless of above 2000-2500 in." None of our Nevada atmospheric temperature, objects exposed to ants can qualify because of the adverb ex- direct sunshine warm up far more rapidly clusively, so we will use the more modest than at sea level" (Mani 1968:21). This is term alpine. enormously important for insects because of The student of mountaintop faunas must the short days and the short summers. be duly warned (as does Mani, p. 4) that 5. Snow cover. This is absolutely essential not all insects occurring at high altitudes for high-altitude insects. It prevents freezing are hypsobionts: "Incredibly large numbers and desiccation and, because the habitat un- of insects [even heavy flying insects] are der the snow is not frozen, makes possible lifted from the lowland by warm updraft air an earlier start of summer activities. currents to high altitudes, to be chilled 6. Biotic factors. (After Mani 1968:44) dead, blown passively and eventually cast Most biotic factors are ultimately based on on high mountain slopes." The converse, the following: however, is not true: hypsobionts are rarely (a) Trees are absent. encountered on the lowlands. (b) The scant cespitose vegetation has a In this study we define a Nevada moun- short growing period. tain ant species as one that inhabits the (c) The active feeding period is severely Coniferous Forest Biome or the Alpine restricted by the short summer. In the Biome or the ecotone between them. We northwestern Himalaya on south cannot use an elevational boundary because slopes the average annual feeding pe- the lower limit of the forest is too uneven. riod may last 10 weeks at 3000-4000 m. On north slopes it starts later and is shorter. High-altitude Environment (d) Sources of food are extremely irregu- local- The high-altitude environment, like all lar, relatively scant, and often others, is a complex of many interrelated ized. Autochthonous sources are plants factors, but it differs from all others in one (1) respect: reduced atmospheric pressure, and animals normally living at high altitudes. which is itself the result of high altitude. This seems to say that the high-altitude en- (2) Wind-blown organisms from the vironment is characterized by high altitude, lowlands are the predominant but we shall avoid being so foolish by de- source and are most abundant at scribing some of the effects of reduced at- the melting edges of snow where mospheric pressure. dead plants and animals (mostly sur- 1. Deficient oxygen, the most important insects) become exposed. The characteristic. In the Himalaya at the tim- face of the snow is likewise im- it is almost the exclusive berline the oxygen is 68 percent of what it portant; source in the Himalaya above is at sea level; at 6000 m it is only 45 per- cent. Mountain sheep, ibexes and yaks live 5000 m. up to 5800 m; man without an artificial ox- (e) Suitable microhabitats are scarce. Ac- ygen supply lives up to 8540 m. Certain in- tually there are only two of any sig- sects, mites, and spiders flourish at 6800 m, nificance: (1) cracks in the soil and because they are only slightly affected by rocks and (2), of far greater impor- decreased oxygen or by sudden changes in tance, under stones. atmospheric pressure (Mani 1968:10). (f) Crowding and isolation, caused by scarcity, result in "a state of 2. Atmospheric cold. While it is true that this may cold does slow down the activities of in- . armed neutrality rather than sects, high-altitude insects can exist only be- peaceful coexistence!" (p. 81) of high-altitude insects cause of the atmospheric cold: it enables (g) The majority them to withstand the atmospheric aridity are predators, parasitoids, or parasites. (Mani 1968:22-23). "It would seem that almost every December 1978 Wheeler, Wheeler: Nevada Ants 381 member of a high-altitude commimity Gregg (1963:446) reported it up to 10,505 spends practically all its time devour- ft in Colorado. So the Nevada record of ing and predating [sic] on every other 11,320 ft on Boundary Peak must be the member species" (pp. 80-81). highest not only in Nevada but also any- (h) The base of the ecological pyramid is where the species is found. CoUembola. (i) The fauna is impoverished in number Adaptations of species (perhaps to only three of four in a community), but the number Because the Arctic-alpine is the harshest of individuals per species may be very terrestrial environment on earth, one may large. ask what special adaptations permit certain species to live and even thrive in it: Ants Recorded from High Altitudes 1. Pigmentation. The insects of high alti- tudes have a large amount of melanin in Weber (1943:341-346) has assembled a their integument. The black color enables list of records with locations and elevations them to warm up faster and earlier in the in meters and in feet. The following totals morning as well as earlier in the season. include only workers recorded above 2000 This ensures them a longer working period m ( = 6560 ft), except in North America during the all-too-short summer. where for some unexplained reason he in- 2.