Blommersia grandisonae is a species of frog in the family Mantellidae. It is endemic to Madagascar. Its natural habitats are subtropical or tropical moist lowland forests, rivers, intermittent freshwater marshes, and plantations . It is threatened by habitat loss.
M 18-23 mm, F 19-20 mm. Hand without webbing, foot webbing 1/(0.75), 2i(1.5), 2e(1), 3i(2), 3e(1.5), 4i/e(2.75), 5(1). Dorsal skin smooth. Very characteristic colouration with a blackish band along the flanks, bordered below by a distinct white stripe. Ventrally with yellow colour.
Ambana, An’Ala, Andasibe, Andringitra (Sahavatoy river), Anjanaharibe-Sud, Ankeniheny, Ivohibe, Mananara, Marojejy, near Ifanadiana, Sahafary.
Habits: Has only been found in primary forest and breeds in slow-moving stretches of forest brooks. Calling males were observed during the night. Males call from vegetation, 20-50 cm above the water in slow-moving portions of small streams.
Calls: A long pulsed chirping note and a rapid series of 5-6 short pulsed notes.
Eggs and tadpoles: Near the calling males at Andasibe, the remaining jelly of some clutches, probably belonging to this species, was still hanging from the vegetation over the brook (0.7 m above water).