Aneuretus simoni
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Aneuretus simoni Image April Nobile, AntWeb |
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| Aneuretus simoni | ||||||||||||
| Emery , 1893 |
Aneuretus simoni is a rare species of ant thatliveson the island of Sri Lanka . The species is the only surviving representative of the subfamily Aneuretinae, of which otherwise only fossil species are known.
features
It is a small, uniformly light brown (from brown-orange to yellowish) colored ant species. The cuticle is smooth, barely shiny and, with the exception of the propodeum, not very sculptured and slightly hairy. Workers are dimensionally dimorphic, they occur in two different size classes (without overlap). The more common small workers reach a body length of around 1.8 millimeters. They have a large, somewhat heart-shaped head with relatively small, flat eyes with about 30 ommatidia , without ocelles. The antennae are twelve-limbed with a long, slender basal limb or scapus. The clypeus is large, not arched, outlined in front and has no central keel. The mandibles are triangular, the chewing bar slightly toothed with truncated teeth, with three large, pointed apical teeth. The Maxillarpalpen are dreisegmentig as the labial palps. The Propodeum has two long, pointed thorns (shorter for the tall workers). The base of the petiolus is very narrow and elongated, with a sharp knot and thickening towards the tip. The knot is twice as wide as it is long when viewed from above. Towards the free abdomen or guest , it is again narrowed. The guest is plump without constrictions. Inside there is a functional poison sting .
Queens are noticeably larger and darker in color than worker women. Their heads are proportionally larger and the thorns of the propodeum are greatly reduced. The larvae are about 0.8 to 1.6 millimeters long and curved in an S-shape, the trunk section (thorax) is set off from the head in the shape of the neck. The intergument has no small thorns and is relatively lightly hairy. The antennae are short and three-segmented, the mouthparts relatively long. The mandibles are heavily sclerotized and triangular. Pupation takes place in a cocoon.
Biology and way of life
Aneuretus simoni lives in nests that are created in the ground or in rotted, lying dead wood. The colonies are relatively small with a maximum of about 100, on average about 65 workers. The large workers (major form) make up only two to three percent of the individuals. The nests usually contain several queens. Encounters with other peoples of the same or different species lead to aggressive behavior. In general, however , aneuretus is quite secret and tends to avoid colonies of other species.
The diet is relatively unspecialized, the species prey on small arthropods, but also accepts rotten fruits as food. Larger and defensive prey is paralyzed with the poison sting. The larvae are fed with pieces of cut up prey organisms. Mutual feeding ( trophallaxis ) is common. As is typical for almost all ants, abundant sources of food are made accessible by permanent paths marked with pheromones ( ant trails).
Distribution and habitat
The species lives exclusively ( endemically ) on the island of Sri Lanka (Ceylon). It lives in primary tropical lowland rainforest , rarely also in secondary forest, whereby it favors forest edges in a striking way. The main area of distribution is the humid interior of the island with annual rainfall amounts of around 2000 to 2500 millimeters. Since around 2001, some occurrences in hill chains with annual dry season are known, which are overgrown by semi-evergreen Dipterocarpus forests.
Phylogeny and Systematics
The species is classified as the only living ( recent ) representative in the subfamily Aneuretinae. Aneuretinae are otherwise known only from a number of fossil species. A number of species come from the Eocene Baltic amber. Others have survived as compression fossils from North American limestone from Florissant, Colorado, and the Green River Formation, which are somewhat younger. Some of the oldest ant fossils from the Cretaceous , for example the genera Burmomyrma from Burmese amber and Cananeuretus from Canadian amber, were assigned to the subfamily. Aneuretus simoni is therefore probably a relic species, the last survivor of a group that used to be almost worldwide.
Numerous morphologically working taxonomists have noticed the similarity of the species to the representatives of the subfamily Dolichoderinae . The discoverer and first describer Carlo Emery had included them in the Dolichoderinae. Only Edward O. Wilson placed them in their own subfamily in 1956, which was later confirmed. The most striking distinguishing feature is the functional poison sting, a plesiomorphism . According to both morphological and phylogenomic analyzes (based on the comparison of homologous DNA sequences) they are probably the sister group of the Dolichoderinae.
The social behavior of the species is, in contrast to other known relic species and groups of ants (for example Amblyoponinae , Leptanillinae , Nothomyrmecia macrops ) relatively progressive and hardly distinguishable from that of the "higher" ants.
Danger
After the Red List of the World Conservation Union IUCN is Aneuretus simoni threatened with extinction (critically endangered category, CR). However, the assessment, which is primarily based on the decline in the then best-known deposit at Ratnapura, investigated by Wilson, does not yet include some more recent finds, so that the actual risk may be lower.
Individual evidence
- ↑ WH Gotwald Jr. (1970): Mouth Part morphology of the ant Aneuretus simoni. Annals of the Entomological Society of America 63: 950-952.
- ↑ EO Wilson, T.Eisner, GC Wheeler, J.Wheeler (1956): Aneuretus simoni Emery, a major link in ant evolution. Bulletin of the Museum of Comparative Zoology of Harvard College Volume 115: 81-99. on-line
- ^ AK Jayasuriya & JFA Traniello (1986): The biology of the primitive ant Aneuretus simoni (Emery) (Formicidae: Aneuretinae). I. Distribution, abundance, colony structure, and foraging ecology. Insectes Sociaux 32: 363-374.
- ^ JFA Traniello & AK Jayasuriya (1986): The biology of the primitive ant Aneuretus simoni (Emery) (Formicidae: Aneuretinae). II. The social ethogram and division of labor. Insectes Sociaux 32: 375-388.
- ↑ DAGNB Karunarathna & WAIP Karunaratne (2013): Two new localities of Sri Lankan Relict Ant Aneuretus simoni Emery, 1893 (Formicidae: Aneuretinae) with the very first record in the intermediate zone. Journal of Threatened Taxa 5 (11): 4604-4607. doi : 10.11609 / JoTT.o3334.4604-7
- Jump up ↑ Gennady M. Dlussky & Alexandr P. Rasnitsyn (2002): Ants (Hymenoptera, Formicidae) of Formation Green River and some other middle Eocene deposits of North America. Russian Entomological Journal 11 (4): 411-436.
- ↑ Michael S. Engel & David A. Grimaldi (2005): Primitive New Ants in Cretaceous Amber from Myanmar, New Jersey, and Canada (Hymenoptera: Formicidae). American Museum Novitates Number 3485, 23 pp.
- ↑ John S. LaPolla, Gennady M. Dlussky, Vincent Perrichot (2013): Ants and the Fossil Record. Annual Revue of Entomology 58: 609-630. doi : 10.1146 / annurev-ento-120710-100600
- ↑ Steven O. Shattuck (1994): Taxonomic catalog of the ant subfamilies Aneuretinae and Dolichoderinae (Hymenoptera: Formicidae). University of California Publications in Entomology 112: 1-241.
- ↑ Philip S. Ward, Sean G. Brady, Brian L. Fisher, Ted R. Schultz (2010): Phylogeny and Biogeography of Dolichoderine Ants: Effects of Data Partitioning and Relict Taxa on Historical Inference. Systematic Biology 59 (3): 342-362. doi : 10.1093 / sysbio / syq012
- ^ IUCN Social Insects Specialist Group 1996. Aneuretus simoni. The IUCN Red List of Threatened Species. Version 2014.3
