Rubus palmatus Thunb. var. yakumontanus (Masam.) Hatus. ex H.Ohba

Family: Rosaceae
Japanese: ヤクシマキイチゴ (屋久島木苺) [Yakushima Ki-ichigo]

This yellow raspberry has maple-shaped leaves with clearly red veins on the undersides and plenty of small thorns on the vine. Look for it at elevations from 600m to around 1500m in sunny areas where the leaves turn reddish. Sour even when ripe.

References:
屋久島の植物ガイド [Flowers guide of YAKUSHIMA] 財団法人　屋久島環境文化財団. 2005.
米倉浩司・梶田忠 (2003-)　「BG Plants 和名－学名インデックス」（YList），http://ylist.info（ 2019年8月14日）