Mystrium species groups

Based on: Yoshimura, M. & Fisher, B.L. 2014. A revision of the ant genus Mystrium in the Malagasy region with description of six new species and remarks on Amblyopone and Stigmatomma (Hymenoptera, Formicidae, Amblyoponinae). ZooKeys 394, 1–99. doi:10.3897/zookeys.394.6446

camillae species group
Alate queen present. Dorsal surface of prono­tum covered with regular reticulation in worker. Second maxillary palpomere shorter than the third in the Malagasy species. Labrum in females gently convex but without median longitudinal carina. Two lateral spines present on abdominal sternum VII in females. Whole vertex sculptured and not smooth in worker. Petiole in dorsal view in females relatively wide (PtI>210 in queen; PtI>180 in worker). Known from the Afrotropical, Malagasy, Indomalaya, and Australian regions.

mysticum species group
Alate queen present. Dorsal surface of pro­notum covered with somewhat irregular striae, and central part of pronotal dorsum covered with fine striae in worker. Second maxillary palpomere longer than the third. Labrum in females with longitudinal carina and strongly convex on its central por­tion. Single lateral spine present on abdominal sternum VII in females. Ventral area of vertex in females not sculptured, smooth. Petiole in dorsal view in females relatively long (PtI<189 in queen; PtI<183 in worker). Known only from the Malagasy region.

voeltzkowi species group
Only ergatoid queen, which is relatively smaller than worker, present; alate queen absent. Dorsal surface of pronotum covered with somewhat irregular longitudinal striae in worker. Second maxillary palpomere longer than the third. Labrum in females gently convex but without median longitu­dinal carina. Two lateral spines present on abdominal sternum VII in females. Whole vertex in females sculptured and not smooth. Petiole in dorsal view relatively long (PtI<195 in queen; PtI<180 in worker). Known only from the Malagasy region.