He's not in "The Oxford Companion to Chess" either (it's a one-vol chess encyclopedia of biographies and chess terms) and I hate to rain on your parade, but I don't think his trap is that well known, after all the Blackmar-Diemer Gambit aint exactly in the same league with the SD Najdorf Variation or Ruy Lopez Marshall Gambit.
Howsumever, that is a snappy trap you posted. Being an old far, er codger I tend to play the spoilsport 4...e3 in this and similar positions which promptly returns the pawn but leaves White stuck with a dumb pawn instead of a smart Kt on f3.
The chess player Hermann Halosar has a trap named after him called the Halosar Trap, but there seems to be very little information about the man himself. I've checked this site, Wikipedia and google but all that comes up is a few games including the well known game against Emil Diemer. Does anybody know any more about this guy? I just find it intriguing how someone can have a well known chess trap named after them but there be very little information out there about that persons life. If anyone can help it'd be appreciated. Here's the trap itself for anyone who's interested: