southern flying squirrel
Refers specifically to Glaucomys volans, a North American species. In everyday Japanese, モモンガ alone often means the Japanese dwarf flying squirrel, so アメリカ is added for clarity.
The southern flying squirrel is a small gliding mammal native to North America.
northern flying squirrel
Standard katakana spelling; usually written in kana.
Kanji spelling using 鼯鼠 (flying squirrel). Rare and mainly encountered in specialized contexts; the kana form is standard.
Compound of アメリカ (America) and モモンガ (flying squirrel). The word モモンガ is of uncertain origin, possibly mimetic or from an older Japanese term.