Mandarin orange (English spelling) mandarinorange

Japanese: mandarin orange（英語表記）mandarinorange

...includes the myrtle-leaf orange, which has extremely small leaves, the bergamot orange, which has a fruit shape and color similar to that of a lime, and the za (sea dwarf orange), which has a thickened calyx. (3) Mandarin orange C. reticulata Blanco (English name: mandarin orange) Generally, it is broadly divided into mandarins, which have a yellow-orange skin, and tangerine oranges, which have a red-orange skin.
[Origin and spread]
All three species are native to southeastern Asia, mainly Assam in India.

From [Mandarin]

...Among the diverse Citrus species, this is a general term for those with thin, easy-to-peel skin. It is an abbreviation of mandarin orange, and is almost synonymous with mikan in the strict sense. The name comes from the fact that the color of the mandarin's uniforms worn by Chinese officials in the Qing Dynasty is the same as that of the fruit itself.

*Some of the terminology that mentions "mandarin orange" is listed below.

Source | Heibonsha World Encyclopedia 2nd Edition | Information

Japanese:

…葉が極端に小さいマートルリーフオレンジmyrtle‐leaf orange，果実の形･色がライムに似たベルガモットオレンジbergamot orange，萼が肥厚したザ(座)ダイダイなどが含まれる。(3)マンダリンオレンジC.reticulata Blanco(英名mandarin orange)　通常，果皮が黄橙色のマンダリンと紅橙色のタンゼリンtangerine orangeに大別される。
［起源と伝播］
　3種ともインドのアッサムを中心とするアジア南東部が原産地。…