Thea Selby, a San Francisco businesswoman and Democratic Party activist, has been named to the California High-Speed Rail Authority board of directors by the speaker of the state Assembly.

Friday's appointment of Selby, a self-described "mom, small business owner and neighborhood activist" who is principal of a San Francisco marketing firm, came with no fanfare from Speaker John Pérez and as something of a surprise to some observers.

Will Shuck, a spokesman for the Speaker's office, confirmed that Selby will replace Thomas Umberg, a Southern California attorney and former state Assembly member who was appointed to the rail board in 2008.

Selby said a friend and mentor, former Assembly Speaker Pro Tem Fiona Ma, had alerted her to the possibility of an opening on the rail board and urged her to apply.

"I've been passionate about transportation for quite some time now," Selby said. She became a fan of high-speed rail after riding fast trains in Japan and Europe, "and I came immediately aware of the benefits of high-speed rail. ... When I started hearing about the possibility of high-speed rail in California, I got very excited."

Selby is a board member of the San Francisco Transit Riders Union, and is also active in Californians for High-Speed Rail, a group that has organized events across the state to provide information and generate support for the rail project. In 2012, she ran an unsuccessful campaign for the San Francisco city and county Board of Supervisors.

Selby said she looks forward to taking a tour of the San Joaquin Valley to learn about the region where the first stages of high-speed rail construction are planned.

"I don't know what it's going to be like on the board, but we really have to go local to listen to people and find out what their issues are," she said. "I want to see the Valley and get a sense of where all this is happening."

Two of the nine seats on the rail authority board are appointees of the Assembly Speaker, and two others are appointed by the Senate Rules Committee. The other five are appointees of the governor.

Umberg served three terms in the Assembly between 1990 and 2006. From 1997 to 2000, he served in the Clinton administration in the Office of National Drug Control Policy. Umberg was the rail authority's chairman in 2011-12.