BOSTON -- Travel startup Wanderu, which has ambitions of becoming the Kayak.com for booking intercity bus and train travel, has raised an additional $5.6 million in financing.

One technology news and information website reports the new round of funding was led by Metamorphic Ventures, and was said to be over-subscribed.

Also participating were Alta Ventures; Craig Lentzsch, CEO of All Aboard Holdings, a motorcoach holding company; 500 Startups; venture capitalist John Balen; early-stage investor Brad Feld; Barbara Corcoran Venture Partners (yes, of television "Shark Tank" fame), and other so-called angels.

Wanderu launched into beta in August 2013, following the close of seed-round financing totaling $2.45 million led by Alta Ventures. (See Sept. 1, 2013, Bus & Motorcoach News).

Lentzsch, the former CEO of the defunct Coach America, and president and CEO of Greyhound from 1994-2003, also contributed to the first round of financing.

At the time, the company had 12 partners, including BoltBus, Go Buses, Concord Coach Lines, and New York Trailways, which allowed it to cover a sizable chunk of the northeastern U.S.

Today, the company reportedly has grown to 40 partners, and covers 70 percent of the U.S.

It now includes access to the largest ground travel providers, including Greyhound, megabus.com, Peter Pan, Grupo Senda and others.

Users come to the Wanderu site, enter their starting and end destinations, and the service offers options on how to get there, taking a cut of the ticket sales booked via its portal.

CEO Polina Raygorodskaya declines to say what the percentage is, but she told one interviewer that Wanderu passed $1 million in monthly sales this past summer, and has continued to grow.

The company says it is growing at 200 percent quarter-over-quarter in users and 400 percent in quarter-over-quarter in sales since its public debut.

It has a team of 17 employees, and plans to use the new capital to expand into Mexico, launch mobile apps, and expand its coverage and services targeted toward millennials.

Wanderu is targeting the younger market, which by some estimates now accounts for the majority of intercity bus travelers.

Around 74 percent of bus travelers are 18-35, Raygorodskaya told one online news service.

"Its becoming much cooler to travel by bus."

"More than 80 percent of our users are under the age of 45 and we have seen incredible return rates," Raygorodskaya says. "Whats most exciting is that weve seen our conversion rate double over the past four months, driven by strong return and repeat user rates, and our push is to rapidly roll out new coverage and features that users are asking for."

In addition to bus tickets, Wanderu offers bus, train and city travel guides on its website, plus details of routes and other information.

The company, which competes with Busbud and GotoBus, plans to build its own brand going forward, rather than license its data to others.