More than 300 critically endangered species have no conservation protection in any part of their ranges, experts say.Bet you can figure out the common name for this little guy. Yep, it's a snake-necked turtle.
Despite increases in the amount of protected land worldwide, many ecosystems fall outside this network of safe havens, scientists say in Nature.
This is because current protected areas do not represent enough of existing global biodiversity, the team claims.
They propose a shift in conservation planning to avoid species extinctions in coming decades.
They found the relationship between protected areas and patterns of biodiversity was uneven.
"Different countries need different levels of protection. Countries with many economic resources can afford that protection," Dr Rodrigues told BBC News Online.
"Most places where we've found these gaps are amongst the poorest countries in the world - poorest from an economic perspective, but richest in biodiversity."
The authors claim the number of species covered by the current network in their paper may be an overestimate because they had to assume that protected areas are adequate for protecting all species and that species can be protected equally effectively in any part of their range.
Gustavo Fonseca, executive vice president for programs and science at Conservation International commented:
"We should focus specifically on those places with the greatest concentrations of threatened and endemic species."