- BY NADIA DRAKE
A new type of tarantula about the size of your face has been found in northern Sri Lanka. Scientists found the spiders — with a leg span up to 8 inches across — living in trees and the old doctor’s quarters of a hospital in Mankulam.
Covered in beautiful, ornate markings, the spiders belong to the genus Poecilotheria, known as “Pokies” for short. These are the tiger spiders, an arboreal group indigenous to India and Sri Lanka that are known for being colorful, fast, and venomous. As a group, the spiders are related to a class of South American tarantula that includes the Goliath bird-eater, the world’s largest.
The new spider, named Poecilotheria rajaei after a local police inspector who helped the team navigate post-civil war northern Sri Lanka, differs from similar species primarily in the markings on its legs and underside, which bears a pink abdominal band.
“This species has enough significant differences to separate it from the other species,” said Peter Kirk, editor of the British Tarantula Society‘s journal, which published a study describing the spider in December. But, Kirk notes, taxonomic determinations based on physical descriptions can provoke disagreement. “I absolutely would love to see DNA sampling done — on all the species ofPoecilotheria,” he said.
The spider’s unique leg markings include geometric patterns with daffodil-yellow and grey inlays on the first and fourth legs. It was first seen during a Sri Lankan arachnid survey led by Ranil Nanayakkara, co-founder of Sri Lanka’s Biodiversity Education and Research. In October 2009, a local villager presented Nanayakkara and his team with a dead male specimen that didn’t resemble knownPoecilotheria in the area. Before the team could begin describing the presumptive new species, they needed more individuals. Scouring the semi-evergreen, forested area for females and juveniles required the help of police inspector Michael Rajakumar Purajah, who accompanied the team through areas just beginning to recover from a civil war. Eventually, the team found enough spiders — including the ones hiding in a hospital — to assemble a detailed description of the new arachnids.
“They are quite rare,” Nanayakkara said. “They prefer well-established old trees, but due to deforestation the number have dwindled and due to lack of suitable habitat they enter old buildings.”
P. rajaei (Ranil Nanayakkara).
Arachnologist Robert Raven, curator at the Queensland Museum in Australia, says the team has done a thorough job describing the spider, but isn’t entirely convinced the team has found a new species — yet.
“The description and figures are excellent and will provide a good basis for establishing whether it is a good species,” he said, noting the possibility that the spiders are a local variant of a related species. Raven says not enough is known about the Poecilotheria genus in general, and that more detailed studies of each known species are needed before new ones can be reliably added. “The genusPoecilotheria has not been taxonomically revised,” he said. “Popping new species out in that situation is always going to be fraught with doubt and difficulty.”
So far, about 15 species have been described within Poecilotheria. Several are endangered, due mostly to loss of habitat. P. metallica, a bright blue beauty, is considered critically endangered. So is P. hanumavilasumica – named after a temple on Rameshwaram Island — which lives among the trees in the island’s disappearing plantations. The spider which most closely resembles P. rajaei is called P. regalis, and so far has only been found on the Indian mainland. Nanayakkara hints that he’s got several more potential new tarantulas up his sleeve, awaiting review.
“When it comes down to taxonomy, it’s not a hard and fast science,” Kirk said. “Until we get to things like DNA sampling.”