Co-linguist

Muslim Bengal asserted its Muslim personality in 1947 against its co-linguist Hindu neighbours. Twenty-four years later, it asserted its regional personality also, through a revolt against its co-religionist West Pakistanis.

Source: wiktionary

The former is capable — when speaking to a co-linguist — of conveying almost a photographic image of an area of bush so extensive is his knowledge of the names of vegetation and descriptions of terrain.

Source: wiktionary

The city of Boston also employs some co-ethnic and co-linguist liaison officers in the city's Office of Neighborhood Services, including people who can speak Chinese, Vietnamese, Spanish and Cape Verdean Creole.

Source: wiktionary

However, in the context of both Afghanistan and the civil war, the fact that most identifiable Afghan groups have co-linguists, co-ethnics, or co-religionists across national boundaries became a catalyst for the nation's collapse

Source: wiktionary