A "distinct subgroup" refers to a smaller and unique group that is part of a larger group. It means that this particular subgroup has its own characteristics or qualities that set it apart from the rest of the larger group. Full definition
The first revealed at least three and possibly four genetically distinct subgroups of Homo neanderthalensis, while the second disputed the contention Neanderthals were cannibals at a Croatian site. (becominghuman.org)
Our results clearly indicate that there are in fact two distinct subgroups within this generation: younger millennials (the «learning generation,» aged 18 - 24) and older millennials (the «engaged generation,» aged 25 - 34). (asiapacific.ca)
The data also confirmed the current division of gorillas into distinct subgroups and identified almost 26,000 differences that can now be used to tell eastern lowland and mountain gorillas, and even the different mountain gorilla clans, apart. (sciencemag.org)