|The Ants of
Genera Stigmatomma Roger and Xymmer Santschi
|Contents - Amblyoponinae - Subfamily Amblyoponinae|
In Tribe AMBLYOPONINI.
Diagnostic Features - Elongated mandibles, pointed at the apex, but not as long as the head, and the tooth row on the inner margin single. Finely sculptured.
Erichson (1842: 260, type species Amblyopone australis, type location Australia); senior synonym of Stigmatomma by Emery & Forel (1879: 455) and its subgenus Xymmer Santschi (1914d: 311), raised to genus in Wheeler (1922: 641), synonymy by Brown (1949c: 87). Erichson's (1842) description (drawing unavailable) is at .
Santschi's (1914d) defintion of Stigmatomma (Xymmer), type species S. (X) muticum - essentially was "Clypeus advanced in a rectangular lobe; mandibles narrow with a range of simple teeth along the internal border; alitrunk narrow with the promesonotal suture distinct, the metanotal suture obsolete; petiole narrow, and elongated in frony, gaster strangled and very long; the rest as for Stigmatomma".
Although Brown (1949c) synonymised Xymmer with Stigmatomma, it is noteworthy that in his review (1960a) he wrote of Amblyopone as having the - "petiole with little or no peduncle"; otherwise he gives no more than a listing of African species.
A primarily savannah genus, described by Bolton (1973a) as rare and little known in West Africa. Arising from the ant ecology investigations at Lamto (Ivory Coast), Brown, Gotwald & Lévieux (1971) wrote how five or six members of the genus, together with Apomyrma stygia, constituted a remarkable and unexpected cryptic soil fauna, with some, perhaps all, feeding on centipedes. Gotwald and Lévieux (1972) described a new species, providing information on its biology, and wrote of "at least four species, Amblyopone mutica, Amblyopone pluto and 2 or 3 other species related to Amblyopone normandi and Amblyopone santschii being found at Lamto". Lévieux (1983b) described the members as subterranean inhabitors of savannah, which feed on geophilid centipedes (see Hölldobler & Wilson, 1990, page 559). The name Amblyopone stygia, is listed in Hölldobler & Wilson (1990, page 559) but this surely is Apomyrma stygia, the only Ponerine species with that specific name. From Bolton (1995) only three species have type locations in West Africa, but three others Amblyopone emeryi, Amblyopone gaetulica and Amblyopone normandi have type locations in North Africa.
Key to Sub-Saharan species. This has changed with the paper by Yoshimura & Fisher
(2012). They revive the monotypic Xymmer and Stigmatomma but gave no key to separate the workers.
|1||Clypeus with unarmed anterior margin (a plate-like projection); petiole ventrally with only a low tubercle, with a distinct narrow peduncle and a narrowed junction with the gaster; head strongly narrowed posteriorly in full-face view; mandibles elongated; generally slender||Xymmer - 2|
|--||Clypeus with dent-like or peg-like projections on the anterior margin; petiole ventrally with a distinct anterior process, no obvious peduncle and more or less broadly attached to the gaster; head rectangular or nearly so in full-face view only weakly narowed posteriorly or not narrowed; mandibles variable; generally stockier||Stigmatomma - 3|
|2||TL 3.5 (including mandibles); petiole in dorsal view an elongated oval; mandible with 10-11 fine teeth; generally yellow-brown||West Africa -
|--||Petiole in dorsal view near rectangular; mandible with five coarse teeth; note - the specimen is a queen; generally lacking in colour||Nigeria specimen|
|3||Petiole ventrally with a low process and attachment to gaster almost as deep as first gastral segment||4|
|--||Petiole ventrally with a well developed process and attachment to gaster not as deep as first gastral segment||5|
|4||TL 5.7-6.4 mm; head rectangular in full-face view; mandibles relatively short and sub-triangular; shiny appearance and head with spaced out punctures; anterior margin of clypeus with a row of peg-like teeth; mainly dark brown and shiny, extremities and appendages progressively lighter||Ivory Coast - Stigmatomma pluto|
|--||TL < 2.5 mm; head slightly narrowed posteriorly in full-face view; mandibles elongated and narrow; anterior clypeal margin with six strongly developed and quite sharp teeth; alitrunk in dorsal view narrow and elongated, propodeum sides straight after metanotum||Kenya specimen|
|5||TL 4 mm; petiole in profile with a relatively narrow attachment to gaster with vertical anterior margin to gaster in profile; anterior margin of clypeus with well developed blunt teeth||West Africa - Stigmatomma santschii|
|--||Petiole in profile with attachment to gaster as wide as first gastral segment; generally stocky||6|
|6||TL ca 1.5 mm; head near square in full-face view; anterior margin of clypeus near smooth and slightly convex; mandibles striate; propodeum in dorsal view near square with a straight posterior margin; sculpturation other than on head much reduced giving shiny appearance to alitrunk, petiole and gaster; head quite coarsely punctate||Rwanda specimen|
|--||Anterior clypeal margin with distinct teeth||7|
|7||TL ca 3 mm; anterior clypeal margin with poorly developed teeth; in dorsal view propodeum with convex margins and strongly widened posteriorly; sculpturation other than on head much reduced giving shiny appearance to alitrunk, petiole and gaster||Cameroun specimen|
|--||TL ca 1.6 mm; anterior clypeal margin with peg-like central tooth and lateral semi-double peg-like teeth; propodeum in dorsal view slightly longer than wide, posterior margin sinuous; general sculpturation a dense reticulo-puncturation||Ghana specimen|
© 2007, 2008, 2010, 2012 - Brian Taylor CBiol FSB FRES
11, Grazingfield, Wilford, Nottingham, NG11 7FN, U.K.