Monomorium, Mayr, 1855

Sharaf, Mostafa R., Fisher, Brian L., Collingwood, Cedric A. & Aldawood, Abdulrahman S., 2017, Ant fauna (Hymenoptera: Formicidae) of the Socotra Archipelago (Yemen): zoogeography, distribution and description of a new species, Journal of Natural History (J. Nat. Hist.) 51 (5 - 6), pp. 317-378 : 347

Key to species of Monomorium of Socotra

(1) Dorsum of mesosoma without projecting hairs ( Figure 16 (a)) .......................................... 2

Dorsum of mesosoma with projecting hairs ( Figure 16 (b))................................................. 3

(2) Colour yellow with the area in front of eyes and gaster except first third of first gastral tergite blackish brown ( Figure 16 (c)); metanotal groove shallowly impressed ( Figure 16 (c)); eyes larger with seven ommatidia in the longest row (EL 0.21 × HW); cephalic surface finely and distinctly longitudinally striated ( Figure 16 (d)); sides of head straight or feebly convex; postpetiole in dorsal view about 1.7 times broader than petiole width ( India, Socotra)................................. ................................. dichroum Forel

Unicolorous clear yellow; metanotal groove deeply impressed and broad ( Figure 16 (e)); eyes smaller with five ommatidia in the longest row (EL 0.19 × HW); cephalic surface unsculptured smooth, and shining; lateral sides of head clearly convex; postpetiole in dorsal view about 1.2 times broader than petiole width ( Socotra, Yemen)......................................................... ......................................................... elghazalyi sp. nov.

(3) Pilosity abundant and clubbed; antennae with 12 segments; eyes large with 10–11 ommatidia in the longest row; mandibles sculptured ( Socotra, Yemen)........................... ............................................................................................................................... nimihil Collingwood

Pilosity few and simple; antennae with 11 segments; eyes smaller with four to six ommatidia in the longest row; mandibles unsculptured except for hair-pits, smooth and shining ............................................................................................................................................... 4

(4) Petiole node nearly as long as broad in dorsal view; petiole peduncle in profile without anteroventral process ( India, Bangladesh, Socotra).................... atomum Forel

Petiole about 1.5 times broader than long in dorsal view; petiole peduncle in profile with a small anteroventral process (Afrotropical and Mediterranean regions, Arabian Peninsula ( KSA))..................................................... ..................................................... exiguum Forel

Figures

Figure 16. Monomorium key illustrations: (a) Mesosoma without hairs. (b) Mesosoma with hairs. (c) M. dichroum. (d) Head of M. dichroum. (e) Mesosoma of M. elghazalyi sp. nov. showing deeply impressed metanotal groove.