Mating is often a risky proposition for male tarantulas, since females tend to eat their heads after the ritual is over. A recently-discovered genus of these arachnids might have the anatomy to avoid this problem.
An international research team led by the University of Turku has dubbed the new genus Satyrex, loosely translated as “Genital King,” per ScienceAlert. Satyr refers to the creature from Greek myths known as a part-man, part-beast with large genitals and “rex” means “king” in Latin.
“The males of these spiders have the longest palps, or mating organs, among all known tarantulas. Our preliminary assumption is that the long palps might allow the male to keep a safer distance during mating and help him avoid being attacked and devoured by the highly aggressive female,” said Dr. Alireza Zamani from the University of Turku, leader of the research recently published in the ZooKeys journal.
In a 2023 article on tarantula mating in the southeastern Colorado grasslands, Scientific American explained that female tarantulas would inject their mates with venom soon after they injected sperm and “immediately take a bite” from the males’ heads. Entomologist Maia Holmes, education and outreach coordinator at the department of agricultural biology at Colorado State University said those tarantula males “weren’t evolved to survive.”
On the Arabian Peninsula and the Horn of Africa, the Satyrex tarantulas roam in burrows at the base of shrubs and near rocks. Their long palps differentiate these spiders from their Colorado counterparts and other tarantulas crawling around the globe.
“Based on their structure and genetic characteristics, they are so distinct from their closest relatives that we had to establish an entirely new genus to classify them,” Zamani explained.
Included in the Satyrex genus are four species: S. ferox, S. arabicus, S. somalicus and S. speciosus. Satryex longimanus was previously grouped in the Monocentropus genus although it has an elongated palp.
S. ferox is the largest, with a legspan of approximately 5.5 inches. Its palp can reach what researchers called an “incredible” length of nearly 2 inches. That’s four times longer than the front part of the tarantula’s body. Typically, palps are around two times the length of a tarantula’s body.
In addition to its impressive palps, the S. ferox is also “fierce” as its name suggests, said Zamani.
“At the slightest disturbance, it raises its front legs in a threat posture and produces a loud hissing sound by rubbing specialized hairs on the basal segments of the front legs against each other,” she said.