Genus Cleostratus Stål, 1877

Type species: Cleostratus monocerus Stål, 1877, by subsequent designation (Kirby, 1910).

Composition. Four species are known from the Philippines: Cleostratus monocerus Stål, 1877, C. depauperatus Günther, 1938, C. helleri Günther, 1938 (all from Luzon Island), and C. longifrons Stål, 1877 (Philippines without specified locality) (Storozhenko, 2016). The images of the type specimens of these species are available at OSF (Cigliano et al., 2025). A new species from Mindanao Island is described and a key to species of Cleostratus is given below.

Key to species of the genus Cleostratus

1(4) Rostrum in lateral view distinctly shorter than the horizontal diameter of the eye.

2(3) Rostrum 1.6 times shorter than the horizontal diameter of the eye. Body light brown.................... C. depauperatus

3(4) Rostrum 3 times shorter than the horizontal diameter of the eye. Body dark brown........................ C. longifrons

4(1) Rostrum longer than horizontal diameter of eye or almost equal to it.

5(6) Rostrum 1.9–2.1 times longer than the horizontal diameter of the eye. Frontal ridge in lateral view deeply excised between eyes. Median carina of pronotum in lateral view sinuous.................................................... C. helleri

6(5) Rostrum almost equal or 1.3–1.4 times longer than horizontal diameter of the eye. Frontal ridge in lateral view slightly excised between eyes. Median carina of pronotum in lateral view straight.

7(8) Rostrum 1.3–1.4 times longer than horizontal diameter of the eye. Hind tibia light brown.................. C. monocerus

8(7) Rostrum almost equal to the horizontal diameter of the eye. Hind tibia black....................... C. omelkoi sp. nov.