female bush tiger mantis
May 21, 2014

New Praying Mantis Species Discovered In Rwanda

April Flowers for redOrbit.com - Your Universe Online

Nyungwe Forest National Park in Rwanda is one of Africa's oldest forests, and at approximately 620 square miles, one of the largest protected mountain rainforests as well. The three types of forest — montane, bamboo and lowland — guard more than 280 species of birds and 13 species of primates, along with a host of other animals and insects. A new study from Case Western University and the Cleveland Museum of Natural History has added a new species of praying mantis to the already impressive list of creatures that call the park home.

Riley Tedrow, a third year evolutionary biology student at Case Western, visited the park as part of a research team led by Cleveland Museum of Natural History's Gavin Svenson. They collaborated with Kabanguka Nathan and Nasasira Richard, from the Kitabi College of Conservation and Environmental Management located near the park in what they believe is the first effort to collect mantids in the park.

The study, published in Zookeys, names the new species Dystacta tigrifrutex, commonly known as the bush tiger mantis. The name is based upon the features of the female, which indicate that she hunts prey strictly on the ground and in the undergrowth, while the male is capable of flying.

"The new species is amazing because the fairly small female prowls through the underbrush searching for prey while the male flies and appears to live higher in the vegetation," said Tedrow.

The name is not all the female provided for the researchers. Shortly after Tedrow reached into the leaf litter surrounding a light trap in the thick, wet night of the Rwandan rainforest and picked up the pair of insects, the female laid an egg case, called an ootheca. The researchers were then the first to see emerging instar nymphs of the species, which is the insect's first stage of development. It is rare that so much of an insect's life cycle can be documented so soon after discovery.

The relatively short trip to Rwanda yielded so many treasures that Tedrow said, "It took eight months to identify all the species."

To be sure they had a new species, Tedrow and Svenson compared the bush tiger mantis with specimens in both the Museum für Naturkunde der Humboldt-Universität in Berlin, Germany, and the U.S. National Museum insect collection, which is on loan to Svenson and is located at the Cleveland Museum. None of the cataloged specimens fit with the bush tiger mantis.

Tedrow also reviewed hundreds of papers describing mantises. None of the species described his find.

The researchers used 21 measurements from the bodies, coloring and more to determine that the new species is from the genus Dystacta, which until this point had only one other species, D. alticeps.

The overall length of both the male and female bush tigers are shorter than the D. alticeps by a third to a half. They have fewer spines on parts of their legs and present different coloration patterns on the prosternum, or underside, where the front legs attach.

"Dystacta alticeps, the sister species, is spread all over Africa," said Svenson, curator of invertebrate zoology at the museum and an adjunct professor at Case Western Reserve. "The new praying mantis species was found in the high altitude rain forest region of southwestern Rwanda and probably only lives within Nyungwe National Park, which adds significant justification for protecting the park to ensure species like this can continue to exist."

One factor in determining one species from another, or how closely related two species are, is the male genitalia. Unfortunately, as the male specimen was drying in the Rwandan heat, hungry ants ate the lower abdomen and accompanying parts.

At the time, the scientists were unaware of the problem, but "unfortunately, they targeted the most important species in the box," Svenson said.

Although the bush tiger mantis was the only completely new-to-science species found, the research team also found 12 species that were new to Rwanda.

Tedrow found the bush tiger mantises in the fringe of the light trap, not in the direct, bright light where entomologists generally find animals to collect. This has Svenson rethinking traditional night-time collecting techniques.

The team plans to return to Rwanda in June. There they will collect more mantises where the bush tiger was found, and investigate other locations as well, hoping to define the range of the new species as limited or broad.

The research trip and study are part of Svenson's Project Mantodea, supported by the Cleveland Museum of Natural History and the National Science Foundation (NSF).