Genus Merma Weise, 1898

Merma Weise, 1898: 123. Type species: Merma limbata Weise, 1898 (by subsequent designation of Korschefsky 1931).

Key to Malagasy species of Merma Weise:

1. Body smaller, below 4.5 mm in length....................................... .............................. 2

-. Body larger, more than 5.0 mm in length.................................... ............................... 3

2. Body larger, about 4.5 mm in length, rounded in outline; elytral margin explanate and well visible from above; elytral epipleuron broad, more than three times as broad as metanepisternum; median part of metaventrite covered with just a few large punctures; abdominal postcoxal lines almost parallel to posterior margin of ventrite 1.................. Merma hovana (Sicard, 1908)

-. Body smaller, about 3.3 mm in length, more elongate in outline, elytral margin not explanate and invisible from above; elytral epipleuron narrow, less than two times as broad as metanepisternum; median part of metaventrite covered with numerous large punctures; abdominal postcoxal lines rounded, not parallel to posterior margin of ventrite 1.................................................................................................. Merma quadriguttata (Sicard, 1909)

3. Ventrite 5 in male apically rounded, apical part of penis with sides subparallel, without lateral projection, with two rows of denticles........................................................................... Merma fisheri sp. nov.

-. Ventrite 5 in male apically emarginate, penis pointed apically, with additional lateral projection, with single row of denticles. ........................................................ ........................................... 4

4. Outer margin of penis guide in lateral view distinctly sinusoidal in middle, tip of penis with narrow lateral thorn-like projection.............................................................................. .. Merma ankarana sp. nov.

-. Outer margin of penis guide in lateral view weakly sinusoidal, tip of penis with broad, subtriangular lateral projection...................................................................................... Merma antakotako sp. nov.