The Giant North American Vinegaroon? It’s Actually Seven Different Species

by AMNH on

Research posts

Vinegaroon walks across a bed of dried leaves.
Giant North American vinegaroon, Mastigoproctus giganteus.
Courtesy of Carla Kishinami/ Flickr

New research on vinegaroons—a group of peculiar arachnids that spray acetic acid (vinegar) from glands in their abdomen as a chemical defense—reveals that what was once thought to be a single species living in North America is actually seven distinct species, of which three are new to science.

“It’s amazing to find a seven-fold increase in the diversity of an entire arachnid order in North America,” said Lorenzo Prendini, a curator in the American Museum of Natural History’s Division of Invertebrate Zoology and a co-author of the paper. “I think this is just the beginning. There’s so much more to discover, even in your backyard, if you look more closely.”


Four different specimens of vinegaroons.
Species of Mastigoproctus A). M. vandevenderi B). M. giganteus C). M. cinteotl D). M. giganteus
© Bull. Am. Mus. Nat. Hist./D. Barrales-Alcalá et al

There are more than 120 known species of vinegaroons, which are found mostly in the tropics, especially in Southeast Asia. Also known as whip scorpions for their whip-like ‘tails’ (technically, flagella), vinegaroons are classified in their own unique order of arachnid, the eight-legged class of arthropods that includes spiders, scorpions, and ticks. These nocturnal predators feed on insects, other arthropods, and small vertebrates such as lizards.

The giant North American vinegaroon, Mastigoproctus giganteus was first described in 1835 and has been known to live across a wide range of habitats in Florida, Texas, Arizona, and central and northern Mexico. Until now, two subspecies of M. giganteus first identified by scientists in the late 1800s and early 1900s were the only additions to this order or arachnids. With taxonomic work on this species dating to more than a century ago and based on just a few specimens, Prendini and two researchers from the National Autonomous University of Mexico saw an opportunity to open a new investigation into the North American vinegaroon.


Vinegaroon specimens.
Top (A,C) and bottom (B,D) views of a Mastigoproctus giganteus vinegaroon. A and B show a male specimen and C and D show a female specimen.
© Bull. Am. Mus. Nat. Hist./D. Barrales-Alcalá et al

Lead author Diego Barrales-Alcalá studied specimens from museum collections across the United States and Mexico, and collected new specimens to conduct a comprehensive study of the vinegaroons’ morphology, or physical characteristics.

The team found that M. giganteus is actually seven distinct species, each with unique physical differences, living in varied regions and habitats, and, in at least two cases, exhibiting different courtship behaviors. The chemical makeup of each species’ defensive secretions also appears to be unique. 

The study, published in the Bulletin of the American Museum of Natural History, opens new avenues for research on these poorly studied animals.

The authors expect that further, ongoing study of genetics and geographical distribution will uncover even more information about these elusive arachnid—and perhaps even more species.