Tetramorium lucayanum

Described from two workers found running on the ground in the Queen's Staircase at Nassau, N. P. (Wheeler 1905). It is most likely native to Africa (Brown 1964).

Identification
Bolton (1980) - The four species placed in the lucayanum-complex of this group all have the dorsal surfaces of both petiole and postpetiole with distinct rugulose sculpture, and usually have the mandibles finely striate. Of the four Tetramorium amissum and Tetramorium tychadion are isolated by having suberect fairly long pubescence on the dorsal (outer) surfaces of the hind tibiae. The remaining two members of the complex, T. lucayanum and Tetramorium versiculum, have decumbent to appressed short pubescence on the hind tibiae. Characters distinguishing these two closely related species are given under T. versiculum.

Distribution based on Regional Taxon Lists
Afrotropical Region: Gambia, Guinea, Kenya, Mali, Sierra Leone. Neotropical Region: Bahamas, Cayman Islands, Cuba, Dominican Republic, Greater Antilles, Netherlands Antilles, Puerto Rico. Palaearctic Region: Ireland.

Nomenclature

 *  lucayanum. Tetramorium lucayanum Wheeler, W.M. 1905b: 100, fig. L (w.) BAHAMAS. Mann, 1920: 406 (q.). Senior synonym of rectinodis: Brown, 1964b: 131; Bolton, 1979: 172; of sexdens, waelbroeki: Brown, 1964b: 131. See also: Bolton, 1980: 340.
 * waelbroeki. Tetramorium camerunense var. waelbroeki Forel, 1909b: 53 (w.) DEMOCRATIC REPUBLIC OF CONGO. Junior synonym of lucayanum: Brown, 1964b: 131.
 * sexdens. Tetramorium lucayanum var. sexdens Forel, 1915c: 357 (w.) IRELAND. Junior synonym of lucayanum: Brown, 1964b: 131; Bolton, 1979: 172.
 * rectinodis. Tetramorium rectinodis Menozzi, 1942: 176, fig. 2 (w.) EQUATORIAL GUINEA (Bioko I.). [Also given as new in Eidmann, 1944: 454.] Junior synonym of lucayanum: Brown, 1964b: 131; Bolton, 1979: 172.

Worker
Length 2.25-2.5 mm.

Head quadrangular, excluding the mandibles somewhat longer than broad. Mandibles broad, s-toothed. Anterior border of clypeus transverse, without teeth. Each frontal carina is continued back as a prominent ruga which, especially behind, bounds a distinct elongate elliptical scrobe for the reception of the antennal scape. Antennae 12-jointed, scape not reaching the posterior corner of the head. Thorax seen from above with prominent humeral angles, in profile with faint but distinct mesoepinotal depression, especially in the pleural region. Epinotal spines rather slender, straight, directed outward, upward, and backward, somewhat longer than the distance between their bases. Episterna produced into prominent spines, fully half as long as those on the epinotum, pointed and curved upward at the tips. Petiole distinctly pedunculate, the node in profile quadrangular, rising abruptly in front, with a horizontal-dorsal surface and steep posterior declivity; seen from above it is oval, somewhat narrower in front than behind, and about 1 1/2 times as long as broad. Postpetiole subglobular, about as long as broad, distinctly broader than the petiole. Gaster rather small. Legs robust, with thickened, fusiform femora.

Body shining throughout. Mandibles rather delicately striato-punctate. Clypeus with several longitudinal rugae. Head and thorax traversed by sharp longitudinal rugae which are not very close together and have a tendency to become reticulate, especially on the thorax; interrugal spaces with shallow punctures which are much finer and denser on the antennal scrobes. Node of petiole with very coarse reticulate rugae, several of which are conspicuously transverse. Postpetiole smooth except for a few longitudinal wrinkles on the sides. Gaster glabrous.

Hairs. pale yellowish, sparse, long, and erect on the body, much shorter, more numerous, and appressed on the antennae and legs.

Black; mandibles, antennae, legs, and tip of gaster reddish yellow; neck, peduncle of petiole, scapes, and femora dark brown.

Bolton (1980) - TL 2.8-3.3, HL 0.72-0.80, HW 0.64-0.72, CI 86-91, SL 0.50-0.61, SI 80-87, PW 0.44-0.54, AL 0.80-0.94 (40 measured).

Mandibles usually delicately longitudinally striate, but almost smooth in some samples. Anterior clypeal margin with a shallow weak median impression or notch. Clypeus with a strong, sharp median carina flanked by a more lateral pair of carinae, otherwise unsculptured. Frontal carinae narrow and fine but — sharply developed, commonly running back almost to the occipital margin but sometimes becoming confused with the other occipital sculpture before reaching the margin. Maximum diameter of eye 0.14-0.17, about 0.21-0.24 x HW, and with 8-9 ommatidia in the longest row. Propodeum armed with a pair of elongate, narrow spines which are usually straight, rarely slightly curved. Metapleural lobes elongate and narrowly triangular, commonly spiniform in their apical portion and somewhat elevated or upcurved, less commonly almost straight. Petiole in profile with a narrow anterior peduncle, the anterior face of the node ascending vertically and meeting the dorsal face in a sharp right-angle. The posterodorsal angle of the node distinctly more rounded than this. In dorsal view the petiole node with a low but sharp crest or carina traversing the anterior face, the node longer than broad even if only slightly so, and the peduncle in dorsal view appearing very narrow indeed. Dorsum of head with widely spaced, sharply defined fine longitudinal rugulae, usually without cross-meshes but sometimes with a few meshes or anastomoses occipitally, never with a developed occipital reticulum. About 9-11 rugulae between the frontal carinae at eye-level. Spaces between the rugulae almost or completely smooth, at most with only faint traces of ground-sculpture. Dorsal alitrunk with sharply defined widely spaced longitudinal rugulae which are less regular than on the head and often a few weak cross-meshes may be present, especially on mesonotum and propodeum. Ground-sculpture between the rugulae almost or completely effaced. Petiole dorsum irregularly and quite strongly rugulose, distinctly more strongly sculptured than the postpetiole which has weak longitudinal rugulae dorsally. Gaster unsculptured. All dorsal surfaces of head and body with numerous standing hairs. Appendages only with fine short pubescence which is usually fairly dense and on hind tibiae is decumbent to appressed. Colour uniform mid-brown to black, the appendages usually somewhat lighter than the body.

Type Material
Bolton (1980) - Syntype workers, BAHAMAS: New Providence, Nassau, Queen’s Staircase, v—vi.1904 (W. M. Wheeler) [examined].

References based on Global Ant Biodiversity Informatics

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 * Belshaw R., and B. Bolton. 1994. A survey of the leaf litter ant fauna in Ghana, West Africa (Hymenoptera: Formicidae). Journal of Hymenoptera Research. 3: 5-16.
 * Bolton B. 1979. The ant tribe Tetramoriini (Hymenoptera: Formicidae). The genus Tetramorium Mayr in the Malagasy region and in the New World. Bulletin of the British Museum (Natural History). Entomology 38:129-181.
 * Bolton B. 1980. The ant tribe Tetramoriini (Hymenoptera: Formicidae). The genus Tetramorium Mayr in the Ethiopian zoogeographical region. Bulletin of the British Museum (Natural History). Entomology 40: 193-384.
 * Borowiec L., and S. Salata. 2018. Notes on ants (Hymenoptera: Formicidae) from Gambia (Western Africa). Annals of the Upper Silesian Museum in Bytom Entomology 26: 1-13.
 * Braet Y., and B. Taylor. 2008. Mission entomologique au Parc National de Pongara (Gabon). Bilan des Formicidae (Hymenoptera) recoltes. Bulletin S. R. B. E./K.B.V.E. 144: 157-169.
 * Brown W. L. Jr. 1964. Solution to the problem of Tetramorium lucayanum (Hymenoptera: Formicidae). Entomological News 75: 130-132.
 * Eidmann H. 1944. Die Ameisenfauna von Fernando Poo. 27. Beitrag zu den Ergebnissen der Westafrika-Expedition. Zool. Jahrb. Abt. Syst. Ökol. Geogr. Tiere 76: 413-490.
 * Menozzi C. 1942. Formiche dell'isola Fernando Poo e del territorio del Rio Muni (Guinea Spagnola). 24. Beitrag zu den wissenschaftlichen Ergebnissen der Forschungsreise H. Eidmann nach Spanisch-Guinea 1939 bis 1940. Zoologischer Anzeiger 140: 164-182.
 * Ross S. R. P. J., F. Hita Garcia, G. Fischer, and M. K. Peters. 2018. Selective logging intensity in an East African rain forest predicts reductions in ant diversity. Biotropica 1-11.
 * Santschi F. 1914. Formicides de l'Afrique occidentale et australe du voyage de Mr. le Professeur F. Silvestri. Bollettino del Laboratorio di Zoologia Generale e Agraria della Reale Scuola Superiore d'Agricoltura. Portici 8: 309-385.
 * Taylor B. 1980. Ants of the Nigerian Forest Zone (Hymenoptera: Formicidae). IV. Myrmicinae (Myrmecinini to Tetramoriini). Cocoa Research Institute of Nigeria Research Bulletin 7: 1-63.