The following are four cases of observed speciation.
1) Speciation occured in a strain of Drosophila paulistorum sometime
between 1958 and 1963 in Theodosius Dobzhansky's lab. He wrote this
up in:
Dobzhansky, T. 1973. Species of Drosophila: New Excitement in an
Old Field. Science 177:664-669
2) A naturally occurring speciation of a plant species, Stephanomeria
malheurensis, was observed in Burns County, Oregon. The citing is:
Gottlieb, L. D. 1973. Genetic differentiation, sympatric
speciation, and the origin of a diploid species of
Stephanomeria. American Journal of Botany 60(6):545-553
3) In the 1940's a fertile species was produced through chromosome
doubling (allopolyploidy) in a hybrid of two primrose species. The
new species was Primula kewensis. The story is recounted in:
Stebbins, G. L. 1950. Variation and Evolution in Plants.
Columbia University Press. New York
4) Finally, two workers produced reproductive isolation between two
strains of fruit flies in a lab setting within 25 generations. I don't
have the paper handy, so I can't give the species. The partial citing
of the paper is:
Rice and Salt 1988. American Naturalist 131:911-