New dragon-like mite found in Ohio is gentle, reclusive

A new species of mite discovered recently in Ohio is so tiny that it lives in the space between particles in sandy, impoverished soils. Despite its dragon-like appearance, Osperalycus tenerphagus is a vulnerable creature and, out of necessity, a recluse.

“These mites are seldom found in soil with high organic content. This is probably because more things live there, including competitors and predators,” says Samuel Bolton, the entomologist who discovered the mite. They do better in adverse habitats where there are few other organisms, even others of its kind. Because these mites abstain from sex, “there is no reason for them to look for mates,” Bolton says

The front end of Osperalycus tenerphagus showing three of its legs and the unusual structure of its skin. (Photo courtesy Samuel Bolton)

The front end of “Osperalycus tenerphagus” showing three of its legs and the unusual structure of its skin. (Low-temperature scanning electron microscope image courtesy Samuel Bolton and Gary Bauchan of the Agricultural Research Service, USDA)

One millimeter or less in length, the tiny wormlike mites of the family Nematalycidae (to which O. tenerphagus belongs) have most likely abstained from sex for a very long time. “Perhaps tens or even hundreds of millions of years, it appears,” suggests Bolton, a fellow at the Smithsonian’s National Museum of Natural History and researcher at Ohio State. They have genitals, “but they seem to have evolved as an all-female lineage. No mating. They lay eggs that don’t need to be fertilized,” Bolton adds.

No male O. tenerphagus has ever been found.

“The Nematalycidae are likely very old,” Bolton observes. “They probably co-existed with the dinosaurs and could date as far back as 400 million years.” Microscopic and extremely slow moving, these bizarre-looking arachnids—cousin to ticks and spiders—are found worldwide. And they may have spread without crossing an ocean. Basically, Bolton explains, they could have dispersed through the soils of the world during the Triassic, when the continents were connected as one large supercontinent.

"Osperalycus tenerphagus," a new mite discovered in Ohio. (Image courtesy Samuel Bolton)

“Osperalycus tenerphagus,” a new mite discovered in Ohio. (Low-temperature scanning electron microscope image courtesy Samuel Bolton and Gary Bauchan of the Agricultural Research Service, USDA)

Bolton discovered O. tenerphagus in soil just across the road from his lab at Ohio State in Columbus in 2010. “It was just a case of wondering one day ‘What’s out in my backyard?’” he says. His paper describing this bizarre new species was published recently in the Journal of Natural History.

The mite moves like a worm, “kind of like a miniature accordion,” Bolton explains. “They contract with longitudinal muscles then extend forward with elastic energy and hydraulic pressure. Their skin (called integument) resembles chain-mail covered in tiny palettes, which lock together when O. tenerphagus is contracted. It has eight legs like other arachnids.

Probably the oddest thing about O. tenerphagus is its mouth. Its name Osperalycus essentially means “purse/bag mouth.” Tenerphagus means “tender feeder.”

Bolton has never seen one eat but he describes the mouth as “a vessel that sort of sticks out—like if you had a pot in front of your mouth attached to your lower lip. It is likely that they put their food in it.”

Delicate bacteria and other fluid-filled organisms go into this vessel, gently collected by hair-like structures on the mite’s limbs nearest its mouthparts, Bolton surmises. “Because these mites are fluid feeders, if their food is ruptured before it gets into the mouth then the fluid is lost. So they must be very gentle.” Once filled, a structure like a straw connected to the mite’s esophagus is stuck into the mouth vessel and sucks up the fluid.

–John Barrat

 

 

 

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