Monomorium xanthognathum

Besides the type material, collections have been made in Cape Flats Dune Strandveld.

Identification
Bolton (1987) - A member of the M. setuliferum species group. A very easily recognizable species, the form of the eyes and mandibles, and the form of sculpture and pilosity coupled with the dimensions given above render xanthognathum unlikely to be confused with any other Afrotropical Monomorium.

The affinities of xanthognathum are, however, in doubt for, although it fits best with other members of the setuliferum-group it is the species which, except for its eyes, most resembles the constituents of the destructor-group. It would be useful to know the male of xanthognathum as this would probably solve the problem immediately, as the known males of the two groups are quite different. For the present, on the evidence of the form of the eyes and lack of transverse sculpture on the propodeal dorsum, I am inclined to place xanthognathum in the setuliferum-group rather than in the destructor-group.

Distribution based on Regional Taxon Lists
Afrotropical Region: South Africa.

Nomenclature

 *  xanthognathum. Monomorium xanthognathum Arnold, 1944: 9, fig. 15 (w.) SOUTH AFRICA. See also: Bolton, 1987: 371.

Worker
Bolton (1987) - TL 1.9-2.3, HL 0.48-0.56, HW 0.44-0.51, CI 88-92, SL 0.30-0.37, SI 70-77, PW 0.26-0.30, AL 0·48-0·52 (3 measured).

Mandibles unsculptured, smooth and shining; the only species in either the setuliferum-group or the Afrotropical salomonis-group fauna to have entirely smooth mandibles. Eyes conspicuously far in front of the midlength of the sides, the maximum diameter of the eye 0.32-0.33 x HW. In profile the eyes reniform and strongly oblique with respect to the long axis of the head. Anterior lobe of eye extending forward and downward on the side of the head and in larger workers almost rounding onto the ventral surface of the head. In full-face view the head broad and the scapes relatively short (CI > 85, SI <80). Metanotal groove deeply impressed in profile. Dorsal surfaces of head, alitrunk, petiole, postpetiole and gaster with sparse standing hairs present and with sparse but relatively long decumbent to appressed pubescence on head, alitrunk and gaster dorsally. Dorsal surfaces of head, alitrunk and gaster smooth and shining, unsculptured and featureless except for scattered hair-pits. Sides of alitrunk unsculptured except for the mesopleuron which is punctulate-rugulose, and the bulla of the metapleural gland which has some faint sculpture present. Colour glossy blackish brown to jet black, the mandibles conspicuously bright yellow.

Type Material
Bolton (1987) - Syntype workers, South Africa: Cape Town, nr Lion's Head, 10.v.1939 [examined].