Ochetellus

The genus Ochetellus was first described by Steve Shattuck in 1992, placing it in the subfamily Dolichoderinae.[2][3] The type species of the genus is Ochetellus glaber, originally described as Hypoclinea glabra by Austrian entomologist Gustav Mayr in 1862.[4] The genus was originally placed in the tribe Dolichoderini.[5] It was later placed under the tribe Iridomyrmecini, now classified as a synonym for the tribe Leptomyrmecini.[6][7]

The genus consists of seven species and three subspecies that were previously placed in the genus Iridomyrmex.[5][8] The genus contains the following species: O. democles, O. epinotalis, O. flavipes, O. glaber, O. punctatissimus, O. sororis and O. vinsoni.[1] The three subspecies classified in this genus are O. glaber clarithorax, O. glaber consimilis and O. glaber sommeri.[9][10]

Dead Ochetellus glaber queen

Ochtellus is a genus of small black ants; each species vary in size, with workers ranging from 1.75 to 3 millimetres (0.07 to 0.12 in) in length and males are smaller at 1.6 millimetres (0.06 in).[4][10][11] The largest ants in the genus are the queens; Ochetellus sororis queens measure up to 4 millimetres (0.16 in).[11] While these ants were formerly placed in the genus Iridomyrmex, there are several features that makes these ants distinct; the compound eyes are differently positioned on the head, and the arrangement of the clypeal margin and mesosoma can also distinguish between the two genera.[5] Ochetellus looks similar to Dolichoderus species, but they are relatively smaller and the petiole is narrow and dorsolaterally expanded. The head is also thinner than most Dolichoderinae ants.[5]

On the head, the occipital border either curves in or curves out, and no ocelli are present. The antennae consist of twelve segments.[2] The mandibles each have six to eight teeth along with a large apical tooth.

Ochetellus ants are native to Australia and have been introduced into New Zealand.[2][12] In Asia, they are native to India, Japan, the Philippines and southern Burma.[2] Species are found on the islands of Fiji, Mauritius and New Caledonia.[13][14] Ochetellus glaber was first sighted in Hawaii in 1977 and is considered an invasive species.[15] Since its introduction, the ant has spread throughout the state, and is now found in Hawaii, Kahoolawe, Kauai, Maui and Oahu.[16] The ant has also been introduced to mainland United States, being found in north-central Florida,[17] where it is localised in Orange County.[18]

Ants of this genus are eurychoric; they have a widespread geographic distribution in many different climates, but they are usually found in dry and mesic habitats.[16][19] They are referred to as a tropical genus, but the type specimen was collected from temperate Sydney.[4][20] They are found in sclerophyll woodland and forests, eucalypt woodland, Casuarina forests, mallee, hillsides, beaches and urban areas.[17] These ants are arboreal ants and nests are located in bark, logs, rotten wood, sand, soil, under rocks and stones, tree stumps and twigs or branches.[2][17][21] In urban areas, colonies are found under cracked paths, inside house walls or in patio areas.[22] Some species are considered pests, and they forage into pastures and houses where they show a preference for fluids and sweets.[17][21] Ochetellus flavipes nesting habits are unique among Australian ants, and they construct small runways across the ground.[23] These nests are structurally similar to nests built by some Polyrhachis ants, which construct platforms woven from plants that house the Hemiptera insects they attend to.

Ochetellus worker visiting a flower

Workers form foraging columns in search of food.[17] They forage into buildings, eucalyptus trees, ground areas or on low vegetation.[17] Workers are both diurnal and nocturnal, but they are not active throughout any 24-hour period.[24] Low activity occurs during clear sunny days; however, colonies are extremely active shortly after rain.

Ochetellus ants are omnivores that feed primarily on arthropods, but they show a preference for fluids and sweets when they enter human houses.[21] Workers will prey on Ornithoptera richmondia eggs, fruit fly pupae, Plutella larvae and attack wasp nests.[17][20][25] Honeydew, nectar, Pacific reef heron feces, carrion, Pandanus fruits, plants, seeds, sucrose, fats and grease will also be consumed.[20][26][27] O. glaber is known to exploit the extrafloral nectaries on plants without providing protection.[28]

Foraging workers often visit Pisonia flowers and will feed on the nectar.[29] Other flowers they will visit include Canavalia, Commicarpus, Ipomoea, Melanthera, Plumbago and Scaevola.[26] Ochetellus flavipes regularly attends the mealybug Prorsococcus acanthodus and protects it by building shelters.[23] They also attend a number of butterfly larvae, including Anthene lycaenoides (Pale Ciliate Blue),[30] Ogyris amaryllis (Satin Azure),[31] Ogyris olane (Olane Azure) and Ogyris oroetes (Silky Azure).[32]

Predators such as other ants and the thorny devil lizard (Moloch horridus) predominantly feed on Ochetellus workers; the number of ants that a thorny devil can consume per minute is around 24 to 45.[33] The total number of ants consumed in a day can be as many as 2,500 individuals, based on an examination of the lizard's stomach contents.[34]

During the nuptial flight, a queen may mate with multiple males, while the males will only mate with a single queen, making them monogynous.[19] However, Ochetellus glaber queens will only mate with a single male, making them polygynous.[20] Sometimes, colonies proliferate by "budding" (also called "satelliting" or "fractionating"), where a subset of the colony including queens, workers and brood (eggs, larvae and pupae) leave the main colony for an alternative nest site.[20]

• List of ants of Australia

• Media related to Ochetellus at Wikimedia Commons
• Data related to Ochetellus at Wikispecies