Nine spiders described by an Instituto Butantan researcher in the journal ZooKeys are tree dwellers in the Atlantic Rainforest and the Cerrado
New tarantula species discovered in Brazil
January 09, 2013
By Karina Toledo
Agência FAPESP – The small, rosy-hair covered body of Typhochlaena amma is far from what we usually think of when we think of tarantulas: large, hairy and scary. With delicate yellow, blue and pink spots on its dark brown back, Typhochlaena costae does not look at all like the giant spiders in horror films.
These and seven other species of arboreal tarantulas were recently discovered in Brazil by researcher Rogério Bertani of the Instituto Butantan’s Laboratory of Ecology and Evolution. The study, conducted from 2004 to 2008 with FAPESP funding
, led to a 94-page article
published in a special October edition of the journal ZooKeys
Within the Typhochlaena genus, Bertani also described T. curumim and T. paschoali for the first time. In the Iridopelma genus, the researcher described I. katiae, I. marcoi, I. oliveirai and I. vanini, and he described P. bromelicola in genus Pachistopelma.
The species are found in the Atlantic Rainforest and Cerrado regions in the states of Pará, Tocantins, Paraíba, Maranhão, Piauí, Sergipe, Espírito Santo and Bahia. The study also allowed the researcher to re-describe some previously identified species, such as T. seladonia and I. hirsutum.
“What we call tarantulas is a large group of spiders from many families and genera that share the common characteristic of fang position. The fangs are parallel to the body axis and move vertically, whereas, in other spiders, they work like a plier opening and closing horizontally,” explained Bertani.
Although many people find tarantulas frightening because of their size—which can reach 26 centimeters from the tip of the front leg to the tip of the back leg—their venom is not harmful to humans.
Of the 2,700 species estimated to exist in the world, 300 have been described in Brazil, and the country has the largest fauna of large tarantulas, including approximately 200 species. Most tarantulas live in nests in the ground, but some arboreal species exist in Asia, Africa and, in particular, the Americas.
“They are lighter, have lost the spikes on the legs and have longer front legs for climbing slippery vertical surfaces more easily. They also have well-developed scopulate pads on the ends of their legs that function as suction cups,” said Bertani.
Similar to other tarantulas, the arboreal species do not use a web to capture their prey but rather build burrows between tree leaves for shelter and to enclose their eggs. They feed on insects and small vertebrates, such as geckos and frogs.
Bertani states that the arboreal tarantulas in the Amazon region are already well known but that only five species have been described between the Northeast, Central West and Southeast regions of Brazil. “We described nine more species in just one study. It shows just how little we still know about Brazilian fauna,” he affirmed.
Only two or three centimeters long, the spiders in the Typhochlaena genus are the smallest arboreal tarantulas in the world. Before Bertani’s taxonomic study, only one species was known in the genus T. seladonia, which was described in 1841.
“All arboreal tarantulas are colorful when young and lose their coloration as they mature. Members of Typhochlaena are the only species that remain colorful in their adult stage,” the researcher explained.
Although the function of the colors has not been completely revealed, it is believed that they are related to the spiders’ relationship with predators.
“It is possible that the dark color helps larger spiders camouflage themselves. As Typhochlaena species remain small even when adults, they retain the same coloring as their young,” said Bertani.
The Iridopelma and the Pachistopelma described are, on average, 10-12 centimeters long. They are born a metallic green color, and with each molting, they change their appearance and become more inconspicuous.
The study also revealed that P. bromelicola and I. katiae share an uncommon characteristic among tarantulas: they live exclusively inside the bromeliads that grow in Northeast Brazil, mostly in Bahia.
“The nine species discovered are quite endemic. In other words, they have very limited distribution. This factor puts them at risk because if their small area undergoes significant change—either due to agricultural activities or climatic change—the spiders will disappear,” said Bertani.
The loss of genetic information would be great, particularly in the case of Typhochlaena. “Phylogenetic analyses showed that the four species discovered in this genus are survivors of a very old group of tarantulas—one of the first to branch off the ancestral lineage,” Bertani said.
Although the study conducted at Butantan did not reveal precisely when these species appeared, Bertani estimates that it was soon after the African and South American continents separated because their closest relatives are African. “This study opens pathways for researchers that work with molecular clocks to study the evolution of these species,” he affirmed.
The discoveries also offer possibilities for scientists that dedicate their work to studying venom. “Tarantula venom is very rich in substances from a pharmacological point of view. For example, a molecule that can be used in the treatment of atrial fibrillation was isolated from one Chilean species,” Bertani noted.
However, in Bertani’s opinion, the most important goal is to offer information for public policy makers to decide where to create environmental protection areas.
“It is believed that this endemism is the result of a natural historical process that possibly affected other plant and animal species. If you analyze the distribution map of many species and they coincide, this means that the area is unique and should be preserved,” Bertani explained.
The article “Revision, cladistic analysis and biogeography of Typhochlaena C. L. Koch, 1850, Pachistopelma Pocock, 1901 and Iridopelma Pocock, 1901 (Araneae, Theraphosidae, Aviculariinae)” (doi: 10.3897/zookeys.230.3500) can be read at: www.pensoft.net/journals/zookeys/issue/230