Three New “Club-tailed” Scorpions Identified

A team of researchers has described three new species and two new genera of “club-tailed” scorpions from the tropical regions of North, Central, and South America, and the Caribbean.

A new species of club-tailed scorpion, Rhopalurus ochoai, which was described from Venezuela. This pale yellow or tan scorpion is named for Peruvian arachnologist Jose Antonio Ochoa Camara, a prolific scorpion biologist who collected most of the type material of this new species. Rhopalurus ochoai is medium-sized (about two inches long) and appears to be restricted to the dry forests of Venezuela.
© The American Museum of Natural History, Universidade de São Paulo, and California Academy of Sciences.

Scorpions are found in every ecosystem on the planet, from cave systems below sea level to the snow-capped peaks of the Alps. Arachnologists estimate that the 2,200 species of known scorpions only encompass about 60 percent of the group’s total diversity.

Although their characteristics vary, the new species—Ischnotelson peruassu and Physoctonus striatus from Brazil, and Rhopalurus ochoai from Venezuela—belong to the same group of club-tailed scorpions, which are usually large-bodied, strikingly colored, and known for emitting a kind of scraping or rattling sound to warn predators.

“At 435 million years old, scorpions are among the oldest living terrestrial arthropods on the planet,” says lead author Lauren Esposito, curator of arachnology at the California Academy of Sciences who completed her Ph.D. in a joint program of the City University of New York and the American Museum of Natural History. “We need to understand what they are and where they live so we can protect them. This review clears up longstanding confusion about the club-tailed group, but there’s still so much to discover.” 

Specimens collected during the study—which were examined and compared with specimens already in museum collections—were detected at night using ultraviolet lights that produce a blue-green fluorescent glow on scorpions’ armor. The study’s authors turned over rocks, searched caves, and explored near rivers and in forests to find male and female representatives of these scorpions. Portable GPS devices recorded the geographical coordinates of each discovery, allowing scientists to trace specimens back to their home environment.

This is an image of a known member of the club-tailed group of scorpions (Rhopalurus agammenom). Though their characteristics vary, specimens of the three new species -- Ischnotelson peruassu and Physoctonus striatus from Brazil, and Rhopalurus ochoai from Venezuela -- inhabit the same overarching group of mostly large-bodied and strikingly colored scorpions.
© Humberto Yamaguti

The authors analyzed DNA samples and compared the physical traits of the hundreds of specimens to reorganize and strengthen scientific understanding of this scorpion group. They also restored a long-forgotten genus (Heteroctenus). 

“This project exemplifies the many uses of natural history collections, without which research of this kind would be impossible,” says Lorenzo Prendini, a curator in the Museum’s Division of Invertebrate Zoology and co-author of the study. “Making use of the vast scorpion collections at the AMNH, among the world’s largest, we were able to combine ‘traditional’ comparative morphological and anatomical data reflecting the physical attributes of these scorpions with DNA sequences from their nuclear and mitochondrial genomes to achieve a more holistic understanding of the evolution and classification of these amazing scorpions.” 

Read the full study, conducted by researchers at the California Academy of Sciences, the American Museum of Natural History, and Universidade de São Paulo (Brazil), in the recent issue of the Bulletin of the American Museum of Natural History.