under-represented
adjective uk/ˌʌn.də.rep.rɪˈzen.tɪd/ us/ˌʌn.dɚ.rep.rɪˈzen.tɪd/
未被充分代表的；代表名额不足的
If a type of person or thing is under-represented in a group or organization, there are not enough of them in it.
Hispanics are under-represented in US political institutions. 在美国的政治机构中缺乏代表西班牙裔的人士。