It is possible that this represents an extreme case of sexual dimorphism, as the first kind of Boslic observed was female, with the second kind being male. However, on the Star Trek: Enterprise episode "Borderland", an alien character can be seen which looks like a male version of the female Boslics, featuring the same forehead but with brown hair and a goatee. If that is to be considered a Boslic, it probably means that the differences observed in others are not due to sexual dimorphism at all, but may result from different subspecies or ethnic groups, or even two entirely different species both using the name Boslic. Perhaps Boslic is the name of a government, of which two or more species are members.