There is a lot of discussion about ujukitsu,
I do not have Tanaka description, but I doubt, that Ujukitsu is yellow, pearshaped fruit.
Tanaka put it in one group with C.tamurana Hort.ex Tan. and C.luteo-turgida Tan. Which are definetly not pearshaped.
And according to:
https://citrusvariety.ucr.edu/crc3467"Notes from Dr. Bitters' 1963 trip to Japan: Average size fruit height 6.2 cm, wide 6.4 cm, yellow orange rind, globose,..."
Fruit in Riverside collection does not fit to description.
In japan pages Ujukitsu
written:
ウジュキツ
宇樹橘
うじゅきつ
or
ホウライカン Houraikan
looks like small orange:
https://www.kudamononavi.com/gallerys/view/id=7269
