(Adds detail on Lonsdale's start in Silicon Valley)

By Dan Levine and Sarah McBride

SAN FRANCISCO, Nov 2 (Reuters) - A woman who accused prominent U.S. venture capitalist Joseph Lonsdale of sexual assault in a civil lawsuit has dropped all of her legal claims against him, according to a court filing on Monday.

Lonsdale, who had denied plaintiff Elise Clougherty's allegations, also dropped counterclaims against her, including defamation, and each side will bear their own costs and expenses connected to the lawsuit, according to a joint filing.

Clougherty, who started dating Lonsdale in 2012 while she was a Stanford University student and he was her mentor, accused him of sexual assault and related charges in a lawsuit filed in January. The case shocked Silicon Valley, in part because of its lurid details.

In a countersuit filed in February, Lonsdale denied the charges, accusing Clougherty of defamation and emotional distress as part of a "vicious and vengeful campaign" that sought to destroy his reputation.

As a result of Clougherty's allegations, Lonsdale, a 2003 graduate from Stanford, was banned from the university's campus.

On Monday, a university spokeswoman said a university investigator had considered "new evidence that came to light during litigation" and determined that Lonsdale did not violate Stanford's sex discrimination policies.

"Accordingly, there is no basis to support a ban from the Stanford campus," the spokeswoman said in a statement.

No further terms were disclosed in the filing on Monday in U.S. District Court in San Francisco.

Lonsdale did not immediately respond to an email requesting comment. Jennifer Lin Liu, a lawyer for Clougherty, declined to comment.

Lonsdale worked as an intern at PayPal in 2002, where he met entrepreneur Peter Thiel and other influential members of the so-called "PayPal mafia." He co-founded secretive technology firm Palantir Technologies, a private company with a valuation of about $9 billion, and is a founding partner of venture-capital firm Formation 8.

Clougherty now works as a data scientist in the Washington, D.C., area, according to her LinkedIn profile.

Sexual harassment has been under the spotlight in recent months in Silicon valley, in large part because of a high-profile discrimination lawsuit brought by a former partner at venture firm Kleiner Perkins Caufield & Byers.

The former partner, Ellen Pao, lost her case earlier this year, but sparked a broad and ongoing discussion about gender issues in technology.

(Reporting by Dan Levine and Sarah McBride; Editing by Andrew Hay and Cynthia Osterman)