Karneios (sic) was an epithet of Apollo in the Peloponnese (see e.g. Pindar, Pythians 5.79-80), and the Karneia his great festival there, esp. in Sparta (Herodotus 7.206, Thucydides 5.75, etc.).
The Suda's headword 'Karnios' is also found twice in Stephanus of Byzantium: as the ktetikon of a city of Aiolis called Karne, and as the ethnikon of an Akarnanian island-city called Karnos. Probably more to the point is a place in SW Lakonia called Karnion, mentioned by Polybius 5.19.4 (Philip V camps there in 218 BCE); Walbank's note suggests that it 'is probably to be identified with the temple of Apollo Carneius on the hill of Knakadion near Las'.