V. C. Andrews has written more books dead than alive, and new Hitchiker's Guide to the Galaxy books are about to start, but in that other direction, of new authors appearing like mushrooms, is also quite old. Pen names were once a way to spoof the sales tracking systems. From bmac's comment, I'm guessing it's someone who used a house name or continued something and is now out on their own. One of the many truths of the industry is that many writers get their start in weird forms of hackery. Tom Perotta wrote under R. L. Stine's name for a while, etc. What amazes me most is when someone does hackwork of the pure and unbridled sort and then manages to emerge as both an artistic and popular force. (In other words, Janet Evanovich did romances under fake names and Robert Meyer has used five or six names to get to the semi-big time but I'm most interested by somebody like Gaiman who went from fast-typing journalist (Duran Duran, etc.) to the wider range of stuff that he does now. That second type interests me most because there's often a clear evolution of techniques. But sure the industry, unlike acting or singing, tends to allow for a certain amount of reinvention as deceptive marketing. I can think of people who are certain that Harper Lee and Shakespeare are pseudonyms and I'm reasonably certain that many franchise writer names are pretty much house names.