The lesser mouse-deer, Tragulus javanicus, is the smallest living ungu
late and it possesses the smallest erythrocytes amongst mammalian spec
ies. We observed pits on its erythrocytes by scanning electron microsc
opy. They were 68-390 nm in diameter (135 +/- 65 nm) and appeared in 1
2.8% of erythrocytes examined. They represent unique structures that h
ave not previously been reported physiologically or pathologically.