Armed to suck blood

Newly dis­cov­ered species of leech has three jaws and 59 teeth

The Prince George Citizen - - Science -

A newly dis­cov­ered blood­suck­ing, olive­g­reen leech with three jaws and as many as 59 teeth has been found about 80 km out­side of down­town Wash­ing­ton, D.C.

A team led by a re­searcher at the Smithsonia­n’s Na­tional Mu­seum of Nat­u­ral His­tory dis­cov­ered the new species, Mac­rob­della mim­i­cus, in the swamps of south­ern Mary­land.

It’s the first time since 1975 a new leech species has been found in North Amer­ica.

Anna Phillips, the mu­seum’s cu­ra­tor of par­a­sitic worms, led the team that made the dis­cov­ery.

She waded in murky wa­ters for days wear­ing shorts – with bare legs and san­dals – look­ing for leeches un­der wood, grass and trash in swampy, al­gae-cov­ered ponds near Nan­je­moy, a small com­mu­nity south­west of Wal­dorf.

The re­searchers’ find­ings of the new species, which is about the size of a cig­a­rette, were pub­lished this month in the Journal of Par­a­sitol­ogy.

Leeches are par­a­sitic worms, and some feed on the blood of their hosts.

In the 1700s and 1800s, doc­tors some­times used them to treat fevers and headaches by “rid­ding a patient’s body of ‘bad blood,’” ac­cord­ing to Smithsonia­n ex­perts.

There are more than 700 species of leeches in the world.

About four years ago, Phillips and her team started to dig into a well-known leech species known to live from the East Coast to the Rocky Moun­tains, in­clud­ing Canada and the south­ern United States.

The re­searchers, from uni­ver­si­ties across North Amer­ica, wanted to de­ter­mine whether the same species lived in such a large geo­graph­i­cal area.

“You see a broad dis­tri­bu­tion with a dif­fer­ent geography, and we were sus­pi­cious,” Phillips said. “Leeches don’t crawl across dry land, so we wanted to see if there was more go­ing on.”

They col­lected hun­dreds of sam­ples of leeches, in­clud­ing six found in swampy ponds in south­ern Mary­land.

Us­ing DNA se­quenc­ing and com­par­isons to more than 100 leech spec­i­mens, they dis­cov­ered the new species.

The leech looked like the well-known M. dec­ora species, but some­thing was dif­fer­ent.

To dis­tin­guish among species, par­a­sitol­o­gists usu­ally look at the way pores are ar­ranged on the bot­tom of a leech.

Leeches are hermaphrod­ites and have what’s known as ac­ces­sory pores that se­crete mu­cus, which helps them stick to­gether while mat­ing.

Sci­en­tists no­ticed these leeches had four ac­ces­sory pores grouped in two rows, like other leeches, but they also had an­other set of pores far­ther back on their bod­ies. They named the new species Mac­rob­della mim­i­cus af­ter the Greek word for “im­i­ta­tor” or “ac­tor.”

“They were over­looked,” Phillips said. “It was un­rec­og­nized that these were dif­fer­ent.”

The species lives pri­mar­ily in the Pied­mont re­gion of the United States be­tween the Ap­palachian Moun­tains and the Atlantic coast.

Phillips said she spent hours with ticks, flies, mos­qui­toes and chig­gers around her, walk­ing in squishy, mucky water while try­ing to find leeches in ponds.

She was un­fazed when a leech would grab on to her leg.

Leeches bite only when they’re hun­gry, she said.

In­deed, when a leech at­taches it­self to her, Phillips “gets pretty ex­cited,” she said.

“They come in very stealthy,” she said. “They use their tail sucker, which is a mus­cle, to at­tach and then spread their mouth out and bite.”

The en­counter doesn’t hurt – “noth­ing like a bee sting,” she said – and she uses a fin­ger­nail to lift them off.

Af­ter a leech fin­ishes, “it will just itch a lit­tle.”

“Ticks and mos­qui­toes are way more scary than leeches,” she said, adding that in her 15 years of study­ing leeches, she has been bit­ten many times.

The leech uses its teeth to bite and siphon blood from its prey – usu­ally frogs, fish and tad­poles, along with the oc­ca­sional hu­man, Phillips said.

It can suck two to five times its body weight in blood be­cause of pockets that ex­pand in its di­ges­tive sys­tem.

Leeches can go up to a year with­out eat­ing, and blood meals can take months to digest.

To de­clare a new species, the team fol­lowed stan­dards set by the In­ter­na­tional Com­mis­sion on Zo­o­log­i­cal Nomen­cla­ture, which keeps rules and makes rec­om­men­da­tions for the sci­en­tific nam­ing of an­i­mals.

Phillips said she and her team are pre­sent­ing their find­ings at con­fer­ences and spread­ing the word on so­cial me­dia.

Michael Tessler, a post­doc­toral fel­low at the Amer­i­can Mu­seum of Nat­u­ral His­tory in New York, said the new species is unique. He com­pared it to the feel­ing of hav­ing an “amaz­ing find of any­thing new in your back­yard.”

“This is re­ally quite close to ma­jor met­ro­pol­i­tan ar­eas where peo­ple have pro­fes­sion­ally stud­ied leeches,” Tessler said. “Peo­ple have had this un­der their noses for so long and not known it.”


Mac­rob­della mim­i­cus, above, is the first new species of medicinal leech dis­cov­ered in North Amer­ica in more than 40 years. Right, Anna Phillips, the Smithsonia­n’s cu­ra­tor of par­a­sitic worms, led a team that dis­cov­ered the new leech in Mary­land.

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