Police nabbed an alleged transit sexual predator when his victim reported an attack through the MTA website, authorities said Thursday.

The 26-year-old woman boarded the Q train at Canal Street and was groped at the Dekalb Avenue station on July 21, authorities said. She snapped two pictures of the alleged assailant and reported it through the MTA's customer service website.

The MTA sent the complaint to the Transit Bureau Special Operations District, and Transit District 2, which polices where the victim boarded, investigated the complaint.

Jonathan Quirindongo, 32, turned himself in on Sunday when he saw that the NYPD had shared the pictures of him with the public, according to Transit Bureau Chief Joseph Fox.

On Monday, the victim identified him in a line-up and Quirindongo was charged with forcible touching, authorities said.

He had been arrested once before for having an illegal knife on him, as well as pot, while trespassing.

Chief Fox said the MTA website is another way that riders can report sex crimes to the NYPD, and that it is a team effort to fight sex crimes in transit. Attacks can be reported anonymously through the site.

"The resolve of victims in these cases is remarkable," he said. "Each victim that comes forward serves to encourage and empower others to do the same."

MTA spokesman Kevin Ortiz said there is excellent collaboration between the MTA and NYPD on fighting sex crimes. "We urge victims of this despicable behavior to report it," he said. "There's a good chance we'll catch them."

The website is part of a larger MTA campaign to fight sex crimes in transit launched last year. More than 200 attacks have been reported through its website since its launch.