We may be finding new ones, but has anyone actually seen a new one evolve in the yard? Has anyone gone to bed with 1 kind of duck in the pen and gotten up with another kind of bird, a duck that can't reproduce with other ducks and, therefore, is no longer a duck?
We're killing species on a massive scale, perhaps larger than any in the history of our home. A large percentage of the sun's energy that impacts earth is converted into some form to feed humans. Nonetheless, there should be some empty niches and critters forming to occupy them.
Loren Eiseley (1957, The Immense Journey, NY: Vintage, p 48) cautions us about the seas, "There are things down there still coming ashore. Never make the mistake of thinking life is now adjusted for eternity. It gets into your head - the certainty, I mean - the human certainty, and then you miss it all: the things on the tide flats and what they mean, and why, as my wife says, 'they ought to be watched.' The trouble is, we don't know what to watch for."
Another candidate is the tropics, whether on land or in the water. My plant friend assures me that speciation (the outcome, not the process) is most evident in tropical zones. She attributed some of it to the sharp climactic differences found in a relatively small area like South Africa (her sister once shared a cigar with Mary Leakey.) However, the Amazon basin is perhaps equally rich with plant and animal forms while more homogeneous in climate.
I fear that Gould's description of the Burgess Shale applies. He reports a large variety of forms that seemed to have appeared suddenly - perhaps dropped from a spaceship, or sprung from viruses carried in a meteor - but with time (and selection pressures?) became more uniform. (Kind of like software before and after Microsoft) Natural Selection is the conservative element, the mechanism that makes life more uniform, that leads us to K selection conditions with larger size, high parental investment, and fewer offspring.(1)
While we may be in stasis, an extended period of no speciation and in combination with mass extinctions, we need to figure out the species question before the meteor comes back.
1) Williams (1997, The Pony Fish's Glow and Other Clues to Plan and Purpose in Nature, :NY: Basic Books) refers to Natural Selection as a primarily conservative, rather than a creative force. The same view was apparently dominant just before Blyth, Wallace, and Darwin mutated it for a while.
2) Finding speciation occurring may be like searching for the foundations of personality. The presumed critical years have steadily gotten smaller over the past decades and have done so less by discovery and more by subtraction. "It's over before 6, try 5." In the case of speciation, we may eventually be looking at deep sea vents as the ultimate repository of life's creation, if for no other reason than we've looked everywhere else.