Mantophasmatodea

http://www.mpil-ploen.mpg.de/mpiltaci.htm

The discovery of the new insect order Mantophasmatodea must rank as one of the most important and exciting biological findings of the decade. Discovering new species of insects is routine, especially since it is estimated that ess than 20% of all insect species have been formally described. However the discovery in 2002 of a new insect order (mainly by K-D. Klass and O. Zompro), the Mantophasmatodea (Heelwalkers or Gladiators) rocked the entomological world, and received huge press coverage. Insect Orders are those groups recognized by people as basic types of insects, such as beetles, stick insects, grasshoppers, and cockroaches. The last time an insect Order was described is nearly a century ago! The actual discovery of Heelwalkers, the reasons why these fairly common and medium-sized insects had evaded scientific discovery for so long, and the rapidly growing findings of the current research make a fascinating story.

The new order was initially constructed for two very old museum specimens from Africa that could not be assigned to any of the existing orders (report in the journal Science, 2002). Although European amber fossils containing immature Mantophasmatodea had been described in 1997, they were, at the time, not recognized as belonging to a new order. An expedition launched to Namibia, the locality of one of the specimens on which the new order was based, collected the first live Heelwalkers. The results of this trip, and additional fieldwork in Namibia (in collaboration with Windhoek Museum staff) procured three species of Heelwalker. For a few months it was thought that the Namibian Heelwalkers were the sole relicts of a group that once had a much wider distribution (as evidenced by the Heelwalker fossils in 45 million year old Baltic amber).

However, after reading the 2002 article describing the new order, a South African entomologist (M. Picker) realized that he and his students had collected Heelwalkers during field trips in the arid Succulent Karoo biome of South Africa. Searching old drawers in South African Natural History museums revealed that earlier collectors had captured and preserved a few Heelwalkers, but had misidentified the wingless insects as immature praying mantids. Specimens collected as early as 1890 were scattered throughout old and forgotten insect collections.

Within a few months an international team linked up with the South African entomologists, and in 2002 ventured into the Succulent Karoo landscape of South Africa to collect live specimens. Eight new species were collected and described, bringing the number of living Heelwalker species to 13. A second trip in 2003 to the Fynbos and Karoo biomes of South Africa produced further new species, which are currently being described. One very interesting result is the high degree of endemism in heelwalkers, i.e., each small geographical area has its own species. Team members from South Africa, Germany, Denmark, Japan, Austria and Italy are presently intensively studying many aspects of Heelwalker biology: the taxonomy and species diversity (mainly based on the structure of the genitalia), the structure of several parts of the body including the circulatory system, the structure of sperm and eggs and chromosomes. The phylogenetic relationships between the known species of Heelwalker, and the evolutionary relationship of this new order to the other insect orders is being studied using DNA and hormone sequencing, the embryonic development, and many aspects of behavior, life history, and habitats. It is foreseeable that within some years the Mantophasmatodea will rank among the most well studied insect orders!

Heelwalkers have a very restricted global distribution, only occurring in the Western parts of Southern Africa, in the Succulent and Nama Karoo and Fynbos biomes (a single specimen was apparently collected in Tanzania). These regions show exceptional levels of diversity and endemism – the Succulent Karoo and Fynbos biomes are listed amongst the world’s top 26 diversity hotspots, and are respectively, the most diverse arid and Mediterranean ecosystems in the world. In this respect Heelwalkers form part of a very rich, endemic and unique insect fauna, comprised of many spectacular insect families that are found nowhere else, or, like the Heelwalkers, have their global distribution centre in these regions. A popular article on Heelwalkers would also showcase some of these other insects, and would include a few pictures showing the arid parts, colloquially known as Namaqualand in full bloom.

The article would also cover the life history of Heelwalkers, and how this is synchronized with the winter rainfall. Eggs hatch on cue with the autumn rains, along with the millions of dormant seeds of the famous Namaqualand annual plants. Both develop in the cold wet winter. By spring, the plants have carpeted the landscape with brilliant displays, and the Heelwalkers have reached maturity. The common name for the order is derived from their habit of keeping the last leg joint and huge tarsal pad up in the air at all times. A large mantid-like head and huge eyes allow these predators to locate their spider and insect prey, which they then capture and subdue using the stout and spiny forelegs. The smaller males locate their mates using a Morse code, tapping form of communication, and the ensuing prolonged copulation lasts for up to 3 days. Eggs are encased in a very hard egg pod and deposited in the soil, to survive the prolonged summer drought and await the next season’s autumn and winter rains.

It is extraordinary that these fairly large and common insects should have evaded discovery for so long. One of the reasons for their escaping scientific scrutiny is their superficial resemblance to immature praying mantids. They also inhabit regions that although biologically very diverse, are relatively poorly studied. Added to this is a nocturnal life style, the insects remaining well concealed at the base of tussock vegetation during the day. It is nevertheless remarkable that an entire order of animals should have remained undetected for so long. The discovery suggests that the inventory of life on the planet is far from complete. Hopefully the Heelwalkers can be employed as a flagship group for the umbrella conservation of other (less charismatic) animals of the Karoo and Fynbos biomes.