Researchers have described a new species and genus of tarantula in Thailand. The jumbo spiders nest inside of bamboo stalks, in a behaviour never documented before in tarantulas.
New research in ZooKeys describes the previously unknown tarantula, which inhabits the forests of Thailand’s Tak province. Named Taksinus bambus, the tarantulas crawl inside the stalks of Asian bamboo (Gigantochloa), where they build their silken burrows.
“These animals are truly remarkable,” Narin Chomphuphuang, a co-author of the new study and a researcher at Khon Kaen University in Thailand, wrote in a guest post for the Pensoft blog. “They are the first known tarantulas ever with a bamboo-based ecology.”
The discovery further reinforces the importance of bamboo to wildlife, while demonstrating the evolutionary adaptability of tarantulas. It also showcases the unknown diversity of Thai forests.
Specimens were gathered in Tak province in July 2020 at an elevation of 1,000 meters. The tarantulas feature black and dark grey bodies and golden yellow bands on their legs. They’re actually very striking.
“We examined all of the trees in the area where the species was discovered. This species is unique because it is associated with bamboo, and we have never observed this tarantula species in any other plant,” Narin wrote. “Bamboo is important to this tarantula, not only in terms of lifestyle but also because it can only be found in high hill forests in the northern part of Thailand,” he said, adding that it’s “not an exaggeration to say that they are now Thailand’s rarest tarantulas.”
JoCho Sippawat, a co-author of the new study and popular wildlife YouTuber, discovered the tarantulas, prompting a collaboration with Chomphuphuang and Chaowalit Songsangchote, an arachnologist at Kasetsart University in Bangkok, Thailand.
The tarantulas were found inside the mature culms of Asian bamboo stalks. Entrances to the nests ranged from just 0.79 to 1.2 inches (2 to 3 centimeters) in width through to full-sized fissures. The arachnids rested within silk-lined, tube-shaped burrows, which were either located in branch stubs or in the middle of bamboo culms. All tarantulas living in the bamboo culms constructed silken retreat tubes that covered the otherwise exposed stem holes (see figure E above for a good example).
As the researchers point out, the tarantulas aren’t capable of making these holes themselves, requiring unintentional assistance from other animals. This is no problem, as bamboo is exploited by all sorts of creatures, from borer beetles and bamboo worms to bamboo-nesting carpenter bees and rodents. Bamboo can also crack on its own, the result of rapid changes in moisture, uneven drying, or drenching followed by rapid drying.
In addition to the novel behaviour and distinct environment (no other arboreal spiders live near this area), the researchers were able to distinguish the species by spotting differences in their genitals. Specifically, the males have a relatively short embolus. The embolus, located on the pedipalps, is used by males to deliver sperm to females during mating.
The newly minted genus, Taksinus, resides within the Ornithoctoninae subfamily of Southeast Asian tarantulas. The team named the new tarantula in honour of the Thai king Taksin the Great, who governed Tak province in the 18th century.
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