The Mk XVI is basically a Mk IX fitted with a Packard Merlin & a 4-bladed prop. The Griffon engined Spitfires originally had 4 blades. Without checking I believe only the final Mk 20 series (& their Seafire equivalents) had 5 bladed props.
PS. According to this the 5-bladed prop was introduced on the Mk XIV.
http://www.spitfiresociety.demon.co.uk/whatmark.htmType 373-Mk XIV
In classic Spitfire tradition, the new engine, a Griffon 61 (and later Griffon 65), was mated to an available airframe- in this case a Mk VIII. To absorb the power generated, a 5-bladed airscrew was introduced. Some of the Mk XIV were produced with a cut-down rear fuselage and "teardrop" canopy for increased visibility. 957 were produced.