Abstract
Madagascar is home to some of the largest and most colorful pygmy grasshoppers (Tetrigidae) in the world, known as 'Malagasy Metrodorinae'. Among them, Devil's pygmy grasshoppers (genus Holocerus Bolívar, 1887) are unique in having two long spines on the back, which are modified internal lateral pronotal carinae. The genus Holocerus was composed of two species - H. lucifer (Serville, 1838) and H. taurus Rehn, 1929 syn. nov., but here it is evidenced that the latter represents a junior synonym of the former. Simultaneously, H. devriesei sp. nov. is described as a species new to science. Holocerus lucifer is a northern species of paler coloration and longer spines (distributed from Marojejy and Maroantsetra in the north to Zahamena in the south), whereas H. devriesei sp. nov. represents the southern and darker species (distributed from Vohimana and Andasibe-Mantadia in the south to the Antongil Bay in the north). There are potential overlaps in the distribution of the two species, but without more georeferenced localities, it is impossible to discriminate whether they occur only sympatrically or also syntopically.