The lowercase (ɽ) was added to Unicode since Unicode 1.0 while the uppercase (Ɽ) has only been added since Unicode 5.0.
The uppercase and lowercase codepoints are U+2C641 and U+027D,2 respectively.
⟨ɽ⟩ is used in the International Phonetic Alphabet to represent a retroflex flap.
Ɽ is also used in the alphabets of several Sudanese languages, including Heiban, Koalib, Moro and Otoro. It is placed after R in alphabetical order.
"Unicode Character "Ɽ" (U+2C64) on Compart AG]". https://www.compart.com/en/unicode/U+2C64 ↩
"Unicode Character "ɽ" (U+027D) on Compart AG]". https://www.compart.com/en/unicode/U+027D ↩