Nothomyrmecia macrops
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Nothomyrmecia macrops , Two Queens and Worker (Photo: CSIRO ) |
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| Clark , 1934 |
Nothomyrmecia macrops is an Australian ant species, which is considered the most primitive still living ( recent ) ant and a " living fossil ". It is therefore referred to in Australia as "Dinosaur ant" ("Dinosaur Ant").
features
Workers of the species reach about 10 millimeters in length with a slim build. They are light yellow-brown in color, the front section of the gaster is somewhat darkened. The animals are relatively weakly sclerotized, the exoskeleton weakly sculptured with numerous long hairs. The head has large complex eyes protruding from the head contour , which sit roughly in the middle of the head, and rudimentary , functionless ocelles . The mandibles are elongated triangular, conspicuously forward, a little less than the length of the head, protruding over the head, the straight chewing bar with ten to twelve small teeth. They have maxillary palps with six and labial palps with four limbs. The long and slender antennae are twelve-limbed (in the males thirteen segments).
The free abdomen or gaster is separated from the trunk section (alitrunk) by the tied-off second segment, which forms a stem member ( petiolus ) that is knot-shaped in the middle . In contrast to the genus Myrmecia, there is no postpetiolus. The animals have a functional poison sting , the sting is described as moderately painful. Workers and sex animals have a stridulation organ between the sternites of the third and fourth abdominal segments. In contrast to all other living ants, the fourth abdominal segment consists of separate tergite and sternite; it is not fused together in a tubular manner.
The queens are, on average, a little larger than the workers. They have working ocelles. Wings are present, but shortened (brachypter) and truncated at the end, they usually reach as far as the third abdomen segment (= first gastric segment); Queens cannot fly. Males have fully developed wings and are able to fly. The wing veins are relatively original; As the only recent ant, it also has two groups of Hamuli for coupling the wings. As a major exception among the more highly developed Hymenoptera, many (but not all) individuals have two spurs on the front rails .
The larvae are of the "myrmecioid" type, that is, they are relatively elongated, slender, slightly curved towards the abdomen, without a detached neck area. Larvae and eggs are very similar to those of the genus Myrmecia . Wheeler and colleagues give a precise description. Pupation takes place in a cocoon.
With 2n = 94, Nothomyrmecia has the highest known number of chromosomes, not only in ants, but even in hymenoptera.
Way of life
Nothomyrmecia lives in small colonies made up of a queen and 50 to 70 workers in an earth nest . It is strictly nocturnal. New states are established by a single queen. This usually mates with one, but in about a third of the cases with two, rarely even with three, males ( polyandry ). The degree of relationship of the workers to one another in different colonies was between 0.57 and 0.64. Workers are therefore less closely related to each other than with just one father (in Hymenoptera: 0.75), but still more closely than with their own offspring (0.5). This means that the conditions of Hamilton's rule for cooperation in the species are still met. As a great exception among the ants, in addition to the usual establishment of new colonies by flocking young queens, there is an unusual second way: When the queen dies, one of the young queens can take her place and thus "inherit" her mother colony. The colonies are therefore potentially immortal. It is unclear whether this inheritance path in ants is original or derived. Colonies with many queens (polygyny) are just as rare as reproductive workers.
The species shows a very primitive social behavior for ants. The queen is virtually never fed by workers and essentially has to take care of herself. There is no specialization of female workers; apart from a weak tendency some prefer to guard the nest entrance. The workers hardly cooperate with one another either. There is no recruitment to abundant food sources, teamwork or mutual feeding.
The species feeds in a predatory manner. Workers swarm out of the nest at night, staying active in very cool temperatures. Overall, however, their level of activity is unusually low for ants, the animals often remain completely motionless for hours, often around two thirds of the total time. The hunt rarely takes place on the ground, but the animals climb trees and bushes. Two-winged birds and Schnabelkerfe are given as prey, and they also use honeydew . When animals from different colonies meet, antagonistic behavior virtually never occurs. It is possible that women workers occasionally join foreign colonies.
Habitat and Distribution
Today the species is only known from South Australia , especially from the Eyre Peninsula (for the first finding see under research history), where it is regionally considered to be moderately frequent. The classification in the Red List of the IUCN 1996 threatened as "extinction (critically endangered) are in the opinion of most experts an outdated state of knowledge again. She lives in a spread in Australia, Mallee mentioned, relatively niedrigwüchsigen eucalyptus TYPES as Eucalyptus oleosa dominated, open shrubbery or open forest formations.The tree and bush species, some of which are widely spaced, reach a height of about 5 to 8 meters.
Phylogeny and Kinship
According to morphological criteria, the closest related genus is Myrmecia , which also lives in Australia and together form the subfamily Myrmeciinae. Some authors also put them in their own subfamily Nothomyrmeciinae. Genetic studies have not so far contributed much to the clarification, but have not contradicted a monophyletic subfamily Myrmeciinae. The sister group of the Myrmeciinae is unknown. Possibly it forms a group with the Myrmicinae and Pseudomyrmecinae , the "myrmecoiden" species complex. According to the review by Philip Ward, who evaluated the literature up to 2007, the (tree-living) Pseudomyrmecinae could be the sister group. Despite its primeval shape and simple social behavior , Nothomyrmecia is probably not completely phylogenetically isolated.
The Myrmeciinae closely resembles a number of fossil species from the Mesozoic Era . At that time they were spread all over the world. The genus Prionomyrmex with the species Prionomyrmex janzeni, described from the Eocene Baltic amber , is very similar to Nothomyrmex . After comparing the morphological features, this was even more closely related to Nothomyrmecia than this was to Myrmecia . The renowned researcher Cesare Baroni Urbani considered the differences to be so insignificant that he combined the genera, our species would then have to be called Prionomyrmex macrops (for reasons of priority) . However, this view has not caught on in the professional world and the old generic name was formally reinstated.
Research history
After John Clark first described the species after two workers found in 1931 , it was not found again for decades. Several collective expeditions in the type region, near Balladonia Station in Western Australia, remained unsuccessful. It was not until 1977 that a group of entomologists succeeded in finding it again. They were on their way to the old find region when they were stopped by a breakdown near Wudduna ( South Australia ). During an evening tour, Robert Taylor suddenly discovered a worker from Nothomyrmecia - more than 1000 kilometers from the place of origin. In contrast, it has never been found in Western Australia to this day. The place of rediscovery was later declared a protected area for the species.
Individual evidence
- ^ Alan N. Andersen: Common names for Australian ants (Hymenoptera: Formicidae). In: Australian Journal of Entomology. 41, No. 4, 2002, pp. 285-293, doi : 10.1046 / j.1440-6055.2002.00312.x .
- ↑ John Clark: Notes on Australian ants, with descriptions of new species and a new genus. In: Memoirs of the National Museum of Victoria. 8, 1934, pp. 5-20.
- ^ Robert W. Taylor: Nothomyrmecia macrops: A Living-Fossil Ant Rediscovered. In: Science. 201, No. 4360, 1978, pp. 979-985, doi : 10.1126 / science.201.4360.979 , PMID 17743619 .
- ↑ George C. Wheeler, Jeanette Wheeler, Robert W. Taylor: The larval and egg stages of the primitive ant Nothomyrmecia macrops Clark (Hymenoptera, Formicidae). In: Journal of the Australian Entomological Society. 19, 1980, pp. 131-137.
- ↑ Matthias Sanetra, Ross H. Crozier: Polyandry and colony genetic structure in the primitive ant Nothomyrmecia macrops. In: Journal of Evolutionary Biology. 14, No. 3, 2001, pp. 368-378, doi : 10.1046 / j.1420-9101.2001.00294.x .
- ↑ Matthias Sanetra, Ross H. Crozier: Daughters inherit colonies from mothers in the "living-fossil" ant nothomyrmecia. In: Natural Sciences. 89, No. 2, 2002, pp. 71-74, doi : 10.1007 / s00114-001-0288-5 .
- ↑ Barbara L. Thorne, James FA Traniello: Comparative Social Biology of Basal Taxa of Ants and Termites. In: Annual Review of Entomology. 48, No. 1, 2003, pp. 283-306, doi : 10.1146 / annurev.ento.48.091801.112611 , PMID 12208813 .
- ↑ a b P. Jaisson, D. Fresneau, RW Taylor, A. Lenoir: social organization in some primitive Australian ants. I. Notomyrmecia macrops Clark. In: Insectes Sociaux. 39, No. 4, 1992, pp. 425-438, doi : 10.1007 / BF01240625 .
- ^ A b Brian L. Fisher: Biogeography. In: Lori Lach, Catherine L. Parr, Kirsti L. Abbott (editors): Ant ecology. Oxford University Press, 2010, ISBN 978-0-19-954463-9 . P. 23.
- ^ Social Insects Specialist Group 1996. Nothomyrmecia macrops. The IUCN Red List of Threatened Species. Version 2014.2.
- ^ A b Philip S. Ward, Seán G. Brady: Phylogeny and biogeography of the ant subfamily Myrmeciinae (Hymenoptera: Formicidae). In: Invertebrate Systematics. 17, No. 3, 2003, pp. 361-386.
- ↑ C. Astruc, JF Julien, C. Errard, A. Lenoir: Phylogeny of ants (Formicidae) based on morphology and DNA sequence data. In: Molecular Phylogenetics and Evolution. 31, No. 3, 2004, pp. 880-893, doi : 10.1016 / j.ympev.2003.10.024 .
- ↑ Philip S. Ward: Phylogeny, classification, and species-level taxonomy of ants (Hymenoptera: Formicidae). In: Zootaxa. 1668, 2007, pp. 549-563.
- ↑ Cesare Baroni Urbani: Rediscovery of the Baltic amber ant genus Prionomyrmex (Hymenoptera, Formicidae) and its taxonomic consequences. In: Eclogae geologicae Helveticae. 93, 2000, pp. 471-480, doi : 10.5169 / seals-168834 .
- ↑ Nothomyrmecia Macrops primitive ant habitat, Poochera, SA, Australia. Australian Heritage Database
