Ant Page #2: Subfamilies In The S.W. US, Hawaiian Islands & Other Tropical Regions    © W.P. Armstrong 12 May 2013     More On Imported Fire Ants    Images Of Ant Subfamilies In Bug Guide Ant Genera Photographed By Alex Wild Ant Images From Arizona October 2012 Ant Images From Arizona Feb 2013 (#1) Ant Images From Arizona Feb 2013 (#2) Images From Salton Sea April 2013 (#1) Images From Salton Sea April 2013 (#2) Ant Images On Hawaiian Island Of Maui

Disclaimer: I am reasonably certain about most of the identifications, especially those verified by James Trager & Alex Wild. For some of the names I used cf. (compare with) because of the difficulty in separating very similar species. On others I simply placed the ants in their respective subgroups of closely-related species. Large, difficult genera often require a specialist for precise species verification. Although identifications from my photo images may be impossible without voucher specimens to examine, comments and/or suggestions about my identifications are welcome. Send E-Mail Message To Wayne's Word:

Siafu (Dorylus gribodoi) Courtesy of April Nobile/ © Ant Web.org

African "army ants" of the genus Dorylus (subfamily Ecitoninae) are often called driver ants or siafu. The live in enormous colonies containing over 20 million individuals. They go on seasonal marching columns of 50,000,000 ants in search of food. Columns are arranged with smaller worker ants being flanked by larger soldier ants. They can potentially devour any animal that remains in their path. Since they consume crop pests, from insects to rats, they are actually quite beneficial to indigenous people. They pose a serious threat to any animals unable to move or when the columns pass through homes. Soldiers have very large and powerful mandibles, and their bite is painful.

Jack Jumper (Myrmecia pilosula) Shannon Hartman / © Ant Web.org

Large, aggressive Australian ants of the genus Myrmecia (subfamily Myrmeciinae) can reach 40 mm in length. They are called bulldog ants or "jack jumpers." Their painful stings are dangerous because they may induce anaphylactic shock in allergic victims. Like honey bees and other hymenopterans, female ants are typically diploid with 2 sets of chromosomes. Males are haploid and develop from unfertilized eggs. The Australian jack jumper worker ant (Myrmecia pilosula) has only a single pair of chromosomes. Male jack jumpers have only one chromosome, the lowest number known for any animal! Left: Jack jumper worker (Myrmecia pilosula) from southern Australia (Shannon Hartman 2011).

Trap-jaw ants of the genus Odontomachus have a pair of large, straight mandibles capable of opening 180 degrees. The jaws are locked in place by a pair of large contracting muscles in the head, and can snap shut on prey or objects when their corresponding latches on the clypeus are triggered. The great instantaneous speed of the muscles is due to elastic energy, like the elastic energy of a crossbow. According to Wikimedia (2013), the jaws of Odontomachus are the fastest moving predatory appendages in the animal kingdom. One study of O. bauri (see next image) at UC Berkeley's Department of Integrative Biology (2006) recorded peak speeds of between 35-64 meters per second (78-145 mph), with the jaws closing within just 0.13 milliseconds (130 microseconds) on average. This is 2,300 times faster than the blink of an eye! The peak force exerted was 100,000 times the force of gravity or 300 times the ant's body weight. The mandibles either kill or maim prey, allowing the ant to bring it back to the nest. Odontomachus can simply open and relock its jaws if one bite is not enough. It can use its jaws to bite off larger chunks of food. The ants were also observed to use their jaws as a catapult to eject intruders or fling themselves backwards to escape a threat.

According to Sheila Patek of the integrative biology research team at UC Berkeley (2006), falcons can dive at speeds up to 300 miles per hour, but they must start from very high altitudes and get a boost from the force of gravity to reach these high speeds (32 feet per second squared). In comparison, animals such as trap-jaw ants and mantis shrimp (which formerly held the record for swiftest strike in the animal world) utilize energy stored within their own bodies. In the plant kingdom, one of the fastest moving structures is the trapdoor of an aquatic bladderwort (Utricularia) that snaps shut in 15 to 20 milliseconds (about 1/60 of a second), roughly the speed of a daylight film camera shutter setting. Compare this rate with 0.13 milliseconds for jaws of Odontomachus bauri! Using the formula Force = Mass X Acceleration, it is easy to see how these small ants can stun or kill small prey with their powerful, fast-moving jaws.

.

Patek, S.M., Baio, J.E., Fisher, B.L., and A.V. Suarez. 2006. "Multifunctionality and Mechanical Origins: Ballistic Jaw Propulsion in Trap-Jaw Ants." Proceedings of the National Academy of Sciences 103 (34): 12787-12792. Full Article

Mandibles Locked In Opened Position Photo by Zach Lieberman. From www.Antweb.org

Mandibles Released In Closed Position Photo by April Nobile. From www.Antweb.org

New Record For Fastest Moving Appendage: According to F.J. Larabee, A.A. Smith and A.V. Suarez (12 Dec. 2018), writing in Royal Society Open Science, the jaws of dracula ant (Mystrium camillae) are the fastest moving appendage in the animal kingdom. Dracula ants get their common name from sucking blood of their larvae. Their record-breaking snaps are 5,000 times faster than the blink of an eye, and three times faster than the jaw-snapping speed of the trap-jaw ant, previously the fastest insect appendage known to scientists. It takes only 0.000015 seconds for the mandibles of the Dracula ant to accelerate to their maximum speed. The ants produce their record-breaking snaps simply by pressing their jaws together so hard that they bend. This stores energy in one of the jaws, like a spring, until it slides past the other and lashes out with extraordinary speed and force—reaching a maximum velocity of over 200 miles per hour. Unlike trap-jaw ants, whose powerful jaws snap closed from an open position, Dracula ants power up their mandibles by pressing the tips together, spring-loading them with internal stresses that release when one mandible slides across the other, similar to a human finger snap. The ants use this motion to stun other arthropod prey. The prey is then transported back to the nest, where it is fed to the ants’ larvae.

The "Formica Subsericea Complex" includes F. subsericea, F. argentea and F. podzolica. Ants of the "Subsericea Complex" occur in the cold northern latitudes. For example F. podzolica occurs in podzolic soils of the Boreal Forest Biome of the northern U.S. and Canada. These are gray-brown soils found primarily on sandy parent materials underlain by igneous rocks of the Canadian Shield.

Sex determination in the more than 12,000 species of ants is typical of the enormous insect order Hymenoptera, including bees and wasps. The method is called "haplodiploidy." Males develop from unfertilized eggs and are haploid with one set of maternal chromosomes. They are not identical clones of their queen mother because of crossing over and random assortment of chromosomes during meiosis (oogenesis). Deleterious (unfavorable) recessive genes are quickly weeded out in haploid males because they are expressed and cannot be masked by dominant genes. Females develop from fertilized eggs and are diploid with two sets of chromosomes. Some references say that larvae destined to become sexually mature queens are "well-nurtured," presumably similar to royal jelly in honey bees; however, other reputable authorities state that selection of a queen in some ant species is a lot more complicated and may involve special eggs destined to become queens (see next paragraph). Queen ants have one of the longest life-spans of any known insects--up to 28 years in captivity!

In zones of hybridization, Pogonomyrmex harvester ant workers of the southwestern U.S. are hybrids between P. rugosus and P. barbatus. They possess the best genetic traits of two species. The queen of each species mates with the males of opposite species. Sexually mature ants (queens and winged males) are purebreds: They are offspring of queen and males of the same species. Young queens need to mate with their own species to produce more purebred queens. They need to mate with the other species to produce "superorganism" workers. This strategy appears to be evolutionarily advantageous to both species.

If the workers of an ant nest can be thought of as the superorganism's body, and the sexuals (queens & males) can be thought of as the superorganism's genetic material, it is as though an animal with the body of a mule has the genetic make-up of a horse and donkey!

Although Pogonomyrmex hybrid workers form a colony and the mule is a single organism, they make an interesting comparison. They both involve a cross between two species that forms a stronger hybrid offspring with the best traits of its parents. The ant colony of hybrid workers functions as a unit that could be described as a "superorganism."

The female horse (mare) mates with a male horse (stallion) to produce more male and female horses. If she mates with a male donkey (jackass) she can produce a male or female mule. The mule is a sterile hybrid with the body size of a horse and the sure-footedness and endurance of a donkey. That is why the mule is essentially a "superorganism" used as a powerful pack animal. In the case of Pogonomyrmex, the hybrid "super-ants" are the workers!

An original 20 mule team wagon train used in 1885 to haul borax from Death Valley to Mojave, a distance of 165 miles. The borax weighed 24 tons and the entire wagon train weighed 36.5 tons (gross weight). The last wagon carried water for the mules during the hot, 10 day journey across the Mojave Desert. Today, a load of this size would be pulled by a 600 horse power Kenworth T-2000 tractor with an air conditioned cab!

The above image shows a single amber twig ant collected 1 November 2013 on the stem of a flowering female shrub that keys out to chaparral broom B. sarothroides, although it is probably a fall-blooming B. pilularis. All of the nearby shrubs are coyote brush (Baccharris pilularis), and I have often seen scattered shrubs in B. pilularis populations that more closely resemble chaparral broom (B. sarothroides), particulary in the fall-blooming months. Other ants in the area (Tapinoma sessile and Formica aerata) appeared interested in the numerous flowering heads of seed-bearing achenes on female coyote brush.

The above ant is Pseudomyrmex apache. Its range includes the southwestern United States and Mexico. It is also reported from nearby Laguna Beach. P. pallidus is very similar and is known from the southern U.S. and Mexico, south to Costa Rica. The identification of P. apache was confirmed by authorities Dr. Alex Wild, University of Illinois and Phil Ward, University of Calif, Davis (personal communication, 4 November 2013). This species belongs to the same genus as the acacia ant (P. ferruginea) of Costa Rica that lives symbiotically with swollen-thorn acacia trees.

Tabove image shows three species of Acacia with swollen stipular spines that are hollowed out and occupied by symbiotic ants. Left: The bullhorn acacia (Acacia cornigera), a swollen-thorn acacia native to Mexico and Central America. In its native habitat, colonies of stinging ants (Pseudomyrmex ferruginea) occupy the hollowed-out thorns and fiercely defend the tree against ravaging insects, browsing mammals and epiphytic vines. In return, the host supplies its little guardian ants with protein-lipid Beltian bodies from its leaflet tips (yellowish granules in photo) and carbohydrate-rich nectar from glands on its petiole (just above the pair of spines). Center: Another Central American swollen thorn acacia (A. collinsii) with an acacia ant (P. ferruginea) sipping nectar from the petiolar nectary. Right: The African whistling thorn acacia (A. drepanolobium). The common name comes from the whistling sound that is produced when wind blows across the large hollowed-out thorns. Since the "thorns" on these trees are technically pairs of modified stipules, they are more correctly referred to as stipular spines.

There are other trees in the Central American rain forest with symbiotic ants. Some of the most interesting are species of Cecropia of the mulberry family (Moraceae), including C. peltata and C. obtusifolia. Cecropia trees are easily recognized by their large, peltate, palmately lobed leaves which are clustered at the ends of relatively few, candelabra-like branches. In Costa Rica, the reason three-toed sloths are often found in cecropia trees is that they are easier to spot in the open, leafless branches compared with other trees. The pithy limbs and stem internodes are usually hollow and occupied by colonies of Azteca ants, a neotropical genus of aggressive, biting ants. The ants commonly feed on the nutritious "honeydew" secretions of mealy bugs, but will also forage for other insect prey. According to D. H. Janzen (Costa Rican Natural History, 1983), during the dry season in the Guanacaste Province of Costa Rica, leafless cecropia trees maintain a crop of tiny leaves bearing minute food bodies for the colonies of Azteca ants.

Ant plants (myrmecophytes) include several genera of epiphytes native to Southeast Asia, the Pacific region and northern Australia. They have swollen (caudiciform) stems covered with spines. Ant plants form a symbiotic relationship with ants and provide habitats for ant colonies high in the forest canopy, protecting them from the elements and also predators because of the spines. Hollow, smooth-walled tunnels and chambers develop inside the stems (caudices), living quarters for the ants. The tuberous stems even develop external entrance holes for the ant colonies, typically Iridomyrmex cordatus. [Argentine ants (Linepithema humile) were formerly placed in the genus Iridomyrmex.] The ants in turn provide defense for the plant and prevent tissue damage, swarming to defend their home if disturbed. The ant colonies also provide nutrients for the plants by leaving wastes within the tunnels inside the caudex. Special glands lining the tunnels then absorb nutrients for the plant. This symbiosis allows the plants to effectively gather nutrients (via the ants) from a much larger area than the roots ever could cover. The following two genera, Hydophytum and Myrmecodia (members of the coffee family Rubiaceae) were photographed at Huntington Botanical Garden.

Any discussion of the diversity and natural history of fungi would be incomplete without mentioning the remarkable fungus-growing ants of the New World tropics. There are approximately 12 genera and 210 species of fungus-growing ants in the Attini tribe. Two of the genera, Atta and Acromyrmex are more commonly known as leaf-cutter ants. Leaf-cutter ants are an important forest herbivore because colonies containing millions of ants harvest leaves from a variety of plants for their subterranean gardens of basidiomycete mycelia. The leaves that are harvested by workers and laboriously carried to their nests are not eaten by the ants. Instead, the ants use the leaves as a substrate to grow fungus that they farm in special areas of their nests. The fungus provides the ant colony with a nutrient food source. Special enlarged mycelial structures called gongylida are rich in glycogen. The basiomycete for Atta cephalotes and Atta sexdens has been identified as Leucoagaricus gongylophorus = Leucocoprinus gongylophorus.

The ant colony is composed of several castes, including the queen, workers and large soldiers who often stand guard at the entrance of the nest, or even go on scouting missions to protect the colony from predators. Like the queen, the males are winged, and their only role is to inseminate the virgin queen. Workers include larger "media workers" who cut and carry leaf sections back to the nest, and "minima workers" who cut the leaves into minute pieces for the fungus garden. They also cover the leaf fragments with their antibacterial saliva which retards the growth of competing fungi, thus protecting their symbiotic fungus that is vital for their survival. They also feed the entire colony of ants.

Interestingly enough, fruiting bodies (basiocarps) of Leucoagaricus species can be found in urbanized areas of North America, including L. americanus and L. naucinus. The two latter fungi have also been listed in the genus Lepiota.

Wikipedia contains a good summary about weaver ants of the genus Oecophylla. Worker ants construct nests in trees by weaving together leaves using larval silk. Bending leaves and pulling them together requires a remarkable degree of coordination and cooperation between many workers. Workers are polymorphic with major and minors. Major workers are 8-10 mm long long, while queens are up to 16 mm, at least in my samples from Thailand. These arboreal ants have enormous colonies consisting of more than 100 nests spanning numerous trees and containing more than half a million workers. Workers and winged ants are collected by people in southeast Asia and eaten as a high-protein food supplement.

Return To WAYNE'S WORD Home Page Return To NOTEWORTHY PLANTS Page Go To Biology GEE WHIZ TRIVIA Page Go To The LEMNACEAE ON-LINE Page