This is copy and paste from a post I did on IBC. Just going through Camellia Forest's catalog I found a few species in the genus Camellia that have smaller leaves and flowers. I did not search for the hybrids from these species, as I ran out of time. But hybrids from the smaller leaf species should also have smaller leaves. The original post on IBC opened with a discussion of using Camellia sinensis as bonsai, hence the first paragraph is about Tea.
C sinensis, tea, has been a favorite bonsai for the Tokugawa family for generations. K. Murata's book
Four Season's of Bonsai has an image or two of Tea as bonsai. Tea makes a decent bonsai, leaves reduce to smaller sizes than many other species of camellia, and the flowers are smaller too though just as nice. Most C. sinensis varieties have single white flowers, but there is a pink flower form too. So using tea as bonsai is a time honored tradition.
Camellia Forest
http://www.camforest.com/ has 6 cultivars of Tea listed. Also check Camellia Forest for species Camellia that have smaller leaves and flowers. C brevistyla, C. cuspidata, C fraterna, C. handelii, C. obtusifolia, C. parvilimba, C. transnokoensis, & C. yuhsienensis are all listed as having smaller leaves. Most have white flowers, though some have other colors. hybrids from these species could have smaller leaves also. While I'm killing time this afternoon, I did not take the additional time to scour the hybrid lists for the hybrids with small leaves.
Note that C. handelii and C. parvilimba have leaves at only one inch, so imagine what could be done with bonsai leaf reduction techniques.
My decade ago foray into Camellia horticulture was not successful, but I am thinking about trying again, hence the research into smaller leaved varieties. Once I get confident about keeping Satsuki azaleas alive, I will 'branch out' and return to Camellia. So far my latest batch of Satsuki is in year 5, so I might be getting close to revisiting Camellia.