Named Core i7-5775C and Core i5-5675, these two Broadwell parts shoul be compatible with current Z97 motherboards after a BIOS update. Despite the new C suffix, both models are unlocked parts like the K series chips from previous generations.
The Core i7-5775C is a quad-core, eight-threaded chip with 3.3GHz base clock, 3.7GHz Turbo, 6MB cache, while the Core i5-5675 is a quad-core, quad-threaded part (no HyperThreading) with 3.1GHz core, 3.6GHz Turbo and 4MB cache. Both parts have Intel Iris Pro Graphics 6200, DDR3L 1600MHz support and a 65W TDP.
Why there are only two chips is hard to say, it could be a combination of multiple factors. There's an increasing shift towards BGA chips and with Skylake just around the corner perhaps Intel didn't want to clog the retail channel with too many new SKUs.
The specification also lists the Core i7-5775R, Core i5-5675R and Core i5-5575R, these are BGA1364 models that are soldered to the motherboard. These parts are used in All-in-One PCs or compact systems with no upgrading capability.