although nobody has observed nor can they, to my limited knowledge, logically explain how such mutation could happen and still result in viable offspring.
Blond hair is a mutation. Blue eyes are a mutation. Lack of melatonin is a mutation. If you have children, they undoubtedly look a bit like you, a bit like his or her other parent, but they look like themselves. Some of this difference is due to mutations.
We can and have observed "viable offspring" with distinct mutations in all sorts of species, although it's easiest in short generation species of course.
There are lots of examples of observed speciation, mostly in biogeographical island populations -
Here are a few for your perusal.
A common misunderstanding is the "crocoduck" canard - that is, mom and dad of one species produce some new species. That's not how it works, as I gather you understand. The changes from generation to generation is not really discernable. Over, say, 30 generations they may be. Over 300, they definitely are. Over 3,000, you may be hard pressed to say they are even related.
Even most creationists accept "descent with modification" and what they call "microevolution." To which I always ask, Ok, please explain the biochemical process that shuts off those "micro" changes over time from continuing on over generations to add up to a "macro" change. If one accepts those tiny changes through generations, I can't understand why they can't accept them adding up to a macro change.
Well thought out and appreciated reply. But macro-evolution, that is mutation from one species to another, has to my knowledge never actually been observed only deduced from a very meager fossil record.
A pale white blonde human can successfully mate with an Australian Aborigine and produce a highly successful female tennis player. And a beagle can, with a little help from a high standing stool, breed something fairly new and bizarre with a Great Dane. But in each case the parents and offspring are members of a single species.
I would not argue that a new species cannot be produced via mutation but it would be helpful and conclusive to see one example of it happening. Maybe we have to wait for another mass extinction to come around before nature feels the need to get creative again in her kitchen.
Have to admit I replied before reading the examples at your link. My understanding of the definition of "species" is maybe more restrictive than that used in those examples since I'd assume (admit I may be wrong) that a London Underground dwelling mosquito may still be similar enough with his surface dwelling cousins to breed a viable (also able to reproduce) offspring. If they can I do not really see how their relationship is much different than that of the beagle and great dane. In other words, the mosquito remains a mosquito and has not evolved into a substantially different creature.
PS: I personally have no religious issues with Evolution. I can believe in God managing the finite and mortal vessels housing conscious and immortal souls on this speck of dust through a billion year evolutionary process more easily than through an instantaneous wave of some vast magic wand. I feel rather sorry for Atheists. The mystery to me is how one can study nature and not see His work.