Arachnologists Discover Three New Species of Club-Tailed Scorpions

An international team of arachnologists has discovered and described three new species of Neotropical ‘club-tailed’ scorpions: Ischnotelson peruassu and Physoctonus striatus from Brazil and Rhopalurus ochoai from Venezuela.

A known species of club-tailed scorpion from Brazil. Image credit: Humberto Yamaguti.

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 scorpion species only encompass around 60% of the group’s total diversity.

“Clocking in at 435 million years old, scorpions are among the oldest living terrestrial arthropods on the planet,” said Dr. Lauren Esposito, curator of arachnology at the California Academy of Sciences.

“We need to understand what they are and where they live so we can protect them.”

In their new study, Dr. Esposito and her colleagues from Brazil and the United States painstakingly revised a large group of Neotropical ‘club-tailed’ scorpions.

After sifting through DNA and comparing the physical traits of hundreds of specimens to reorganize (and strengthen) scientific understanding of this scorpion group, the researchers described two new genera, Ischnotelson and Jaguajir, and restored a long-forgotten group called Heteroctenus.

The authors also described three new species: Ischnotelson peruassu, Physoctonus striatus and Rhopalurus ochoai.

Ischnotelson peruassu, dorsal (A) and ventral (B) aspects. Scale bar – 10 mm. Image credit: Esposito et al.

Though their characteristics vary, specimens of the three new species inhabit the same overarching group of mostly large-bodied, strikingly colored, and sonically gifted scorpions.

“Savannas, caves, deserts, open fields, and forests — you name the Neotropical landscape, and we can show you a club-tailed scorpion that lives there,” Dr. Esposito said.

“One wild thing about this group is that many species have the unique ability to make sounds by rubbing a specialized comb-like structure against their sandpaper-like abdomen.”

“We think it’s probably a loud way to tell predators: ‘back off’.”

“The warning is audible to the human ear. It sounds like hiss, or even like a maraca shaking.”

Rhopalurus ochoai, dorsal (A) and ventral (B) aspects. Scale bar – 10 mm. Image credit: Esposito et al.

Ischnotelson peruassu is a medium-sized scorpion (total length – 4.8 to 5.9 cm).

The species is known from only two adjacent localities within the Parque Nacional Cavernas do Peruaçu, in the Municipio Januária of northern Minas Gerais state, Brazil.

Physoctonus striatus is a small scorpion (total length – 2.2 to 2.6 cm). It is known only from the type locality in the Brazilian state of Bahía.

Rhopalurus ochoai is a medium-sized, compact scorpion (total length – 4.1 to 4.9 cm).

It appears to be restricted to northwestern Venezuela, where it has been recorded around Lake Maracaibo in the states of Trujillo and Zulia.

The new species are described in a paper published in the Bulletin of the American Museum of Natural History.

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Lauren A. Esposito et al. 2017. Systematic revision of the Neotropical club-tailed scorpions, Physoctonus, Rhopalurus, and Troglorhopalurus, revalidation of Heteroctenus, and descriptions of two new genera and three new species (Buthidae, Rhopalurusinae). Bulletin of the American Museum of Natural History 415: 134 pp.; digitallibrary.amnh.org/handle/2246/6723