[yodasan]

I'd suggest talking to the cofounders in a non-accusatory manner. Startups are often disorganized and crazy and my guess is that the tax implications of your shares didn't even cross their minds because there are so many things going on. Also, what was the previous investment amount? If the previous investment is from a family or friend, my guess is that it's more of a bridge than an investment to keep the company afloat until true investment comes in (not enough to raise salaries). Either way, I'd give them the benefit of the doubt and not jump to conclusions too early before talking to them.