Clearly your statement:
quote:
For there to become a new species, there must be a different number of chromosomes,
can't be true, as many species share the same number of chromosomes. Chromosome addition/deletion is rare, except in plants that can hybridize.
As per distinct species there are two answers:
1. Species aren't as distinct as you might think. The edges are blurry. Check out information on "ring species", for example. It's very difficult to draw lines between many species.
2. However, there is some reality to the concept of species - the divisions aren't arbitrary. But how is this inconsistent with evolution? Today's living species represent a cross section of the branches of an evolutionary tree - you would therefore expect distinct groups of organisms, not completely smooth gradations between groups. The smooth gradations occur through time, not within one slice of time.