July 3, 2001 Put four international scientists out into the field and what do you get? A profound zoological discovery, and a tricky one at that.
Associate Professor Andy Austin, who heads the newly formed Centre for Evolutionary Biology & Biodiversity at Adelaide University, is one of the Australian, New Zealand and Canadian team who have discovered a new family of parasitic wasps in the windy islands of New Zealand. Their discovery has just been published in the June edition of the prestigious journal Invertebrate Taxonomy.
"Although hundreds of new insect species are described every year, the discovery of a new family is very rare," said Professor Austin. "There have only been 5 or 6 new families described from Australasia in the past thirty years, and that is high compared with the rest of the world," he said.
Students learn the hierarchy of their zoological groups through the mnemonic: King Prawns Caught On Friday Get Stale. Within the animal Kingdom, there are thirty or so major groups, each known as a Phylum. Insects form one Class of that Phylum, and wasps, ants and bees together comprise an Order within it. The next category is the Family. Among the mammals, all dogs, wolves and similar animals fall into one Family, while all kangaroos and wallabies comprise one Family within the Order of marsupials. Zoologically speaking, this new discovery is at that level.
"The vast majority of species belong to families that had been described by the start of the 20th Century," said Professor Austin. "Families that have avoided discovery have done so usually because they are extremely rare, only found in very isolated places, or very small."
All conditions apply to the newly described wasps; they are only 1.5 mm long, and they are bizarre as well. "The new family has extremely unusual features," said Professor Austin. "It appears to be a composite of two unrelated wasp groups, with the front end typical of one group and the back end of another," he said. "Although the first species were collected in the 1970s, it has take until now to work through the problem"
That long puzzle has produced the name of the new family, 'Maamingidae' which is derived from a Maori word meaning 'trickster', and refers to the unusual combination of characters that initially baffled the research team.
Australia and New Zealand were once united with Africa, South America, India and Antarctica to form the supercontinent of Gondwana. As Gondwana broke apart, the separate continents formed isolated islands, carrying plants and animals of that time, which then evolved in isolation.
In islands that remained separate, it is still possible to find descendants of those more primitive organisms, often highly adapted to their local environments. These Maamingid wasps are among them. Some have very short, functionless wings, a great advantage on a windy island where even a short flight might carry you into the ocean.
A related study to be published later this year, has compared DNA from other wasps with that of the new family, and traced its closest relatives to others whose ancestors evolved in Gondwana. The Family's closest living relatives are mostly only found on Australia, New Zealand and South America, the 'left-overs' of the supercontinent.
Other aspects of the insects' natural history remain a mystery, but will form the next stage of the researchers' study. "We know that they are mostly found in and around leaf-litter, and mostly during summer to early autumn," said Professor Austin. "As to what they parasitise, we don't yet know this either, but given that the two closest families parasitise the larval stages of flies in leaf-litter, this is what we would predict as the biology of the new family."
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