Monomorium exiguum

The tiny yellow workers of Monomorium exiguum can be found throughout Madagascar but are most abundant in Toliara Province, where they are often among the most commonly collected Monomorium in sifted litter samples (Heterick 2006). Collingwood et al. (2004) found that this species apparently inhabits leaf litter or topsoil. In Yemen it was found nesting under a stone next to a large fig tree and inside the galleries of a termite nest. The soil was dry with ample dry seeds. Another nest series was found in leaf litter next to a date palm tree where the soil was rich in decaying organic material (Sharaf et al., 2017).

Identification
Heterick (2006) - A member of the M. exiguum complex in the M. monomorium species group. Based on comparative type material I have seen, Monomorium exiguum is part of a complex that includes, at least, the exclusively African Monomorium mictilis, Monomorium rosae and Monomorium taedium. An 11-segmented antenna, an elongate and flattened head capsule, weakly developed clypeal carinae, a dorsally rather flattened rather than evenly convex propodeum and the low, strongly conical form of the petiole are common to all of these taxa. Monomorium rosae is placed in a different complex by Bolton (1987) on the basis of the appearance of the worker postpetiole, but in actual fact, the shape of the postpetiole in larger, darker specimens of Monomorium exiguum approaches that of M. rosae, if it is not identical. The degree of obliqueness seen in the posterior face of the postpetiole appears to be proportional to the size of the worker, rather than a distinct feature at the species level, let alone the species-complex level, in all three species mentioned above.

The distinction between the above four species, if indeed it truly exists, is minimal. In appearance the workers form a continuum, with the bright yellow M. mictile being the smallest species and the very dark M. rosae the largest. To give just one instance, the relevant measurements supplied by Bolton (1987) for M. exiguum (40 specimens) and M. rosae (12 specimens) certainly give this reviser pause for thought! With M. exiguum in regular font, M. rosae in bold, these read: TL (i.e., total length); 1.5–1.7/1.6–2.0 HL 0.36–0.42/0.42–0.50, HW 0.28–0.32/0.33–0.40 CI (=CeI) 74–80/76–82 SL 0.22–0.27/0.28–0.35 SI 74–84/85–94 PW 0.17–0.21/0.21–0.25 AL (i.e., mesosoma length) 0.36–0.44/0.42–0.56. Apart from the larger size, the only real difference that I can discern between a M. rosae Santschi syntype from the Democratic Republic of Congo and large, brown specimens of M. exiguum I have seen from Madagascar is the presence of faint sculpture on the lower mesopleuron in M. rosae. Fresh M. rosae material, which I have not seen, is said by Bolton to be ‘blackish-brown to black’.

Monomorium mictile is separated from M. exiguum by Bolton (1987) on the basis of the presence or absence of erect infrahumeral setae. These are supposedly absent in M. mictile and long and erect in M. exiguum. In fact the setae are present, but short and appressed in M. mictile. This particular character does not seem to be useful as a means of separating similar species in the M. monomorium species group, at least in Madagascar. Where hundreds or even thousands of workers are available for examination, I have noticed variability in the number, length and alignment of the promesonotal setae, including differences in the length and alignment of the infrahumeral setae. This phenomenon may not be recognizable where only a few, isolated specimens are available for study. For now, I would allow for the separation of M. mictile from M. exiguum, as all Malagasy specimens I have seen of the latter have erect or semi-erect infrahumeral setae (albeit of different lengths). The same applies to Monomorium taedium, for which I have seen three paratype workers. Apart from their somewhat larger size (HW = 0.34 mm) and lack of erect infrahumeral setae they look exactly like brown M. exiguum. Interestingly, the postpetiole of the paratype specimens of M. taedium is quite globose, as in smaller M. exiguum.

Interestingly, the paler ‘flavescens’ and ‘bulawayense’ forms also occur in Madagascar, along with M. exiguum sensu stricto. In the taxon faurei the head is darker than the mesosoma, and the gaster is pale with darker infuscation on its basal half, as well as on the sides of the first gastral tergite. This variant, too, is quite common on Madagascar. Monomorium exiguum workers from Madagascar tend to have a slightly more tapered petiolar node than their counterparts on the African mainland.

Distribution based on Regional Taxon Lists
Afrotropical Region: Cameroun, Central African Republic, Democratic Republic of Congo, Ethiopia, Gabon, Ghana, Guinea, Ivory Coast, Kenya, Nigeria, Saudi Arabia , Socotra Archipelago, United Arab Emirates, United Republic of Tanzania, Yemen, Zimbabwe. Palaearctic Region: Balearic Islands, Oman.

Biology
Aldawood & Sharaf (2011) - The Monomorium dryhimi type (a synonym of M. exiguum) was taken from a nest under a stone on hard-packed soil which contained tens of workers and was found in relatively elevated area of a valley which is high enough to avoid direct impacts of flooding. No additional nests were found despite extensive surveys. In addition, we were not able to collect foraging workers near the nest. It appears that members of the Monomorium monomorium group may prefer inhabiting areas of high elevations. All the four Arabian species were found inhabiting elevated localities with more than 1800 m asl., except Monomorium clavicorne which was also recorded from both relatively lower elevated areas including Riyadh and Al Qatif, in Central and Eastern regions of Saudi Arabia, respectively, and also from a much elevated area, Fayfa, Asir province (Collingwood 1985). Apparently this species is endemic to the chain of Asir Mountains which extends to Yemen.

Habitat
Aldawood & Sharaf (2011) - The type locality of Monomorium dryhimi is a forest called Amadan, Al Mandaq governorate, Al Bahah province, Kingdom of Saudi Arabia, with much wild vegetation including Erica arborea L, Juniperus procera Hochst. Ex Endle. and Acacia gerrardii Benth.

Nomenclature

 *  exiguum. Monomorium exiguum Forel, 1894b: 85 (w.) ETHIOPIA.
 * Heterick, 2006: 118 (q.m.).
 * Combination in M. (Martia): Forel, 1913h: 351.
 * Combination in M. (Lampromyrmex): Wheeler, W.M. 1922a: 876.
 * Senior synonym of bulawayensis, faurei, flavescens: Bolton, 1987: 388.
 * Senior synonym of minutissimum: Heterick, 2006: 116.
 * Senior synonym of exiguum: Sharaf, Collingwood, et al., 2015: 52.
 * Senior synonym of baushare, garahe: Sharaf et al., 2017: 343.
 * bulawayensis. Monomorium (Mitara) exiguum var. bulawayensis Forel, 1913j: 217 (w.) ZIMBABWE.
 * Combination in M. (Lampromyrmex): Wheeler, W.M. 1922a: 876.
 * Junior synonym of exiguum: Bolton, 1987: 388.
 * desertorum. Monomorium desertorum Collingwood & Agosti, 1996: 344 (w.) SAUDI ARABIA.
 * Junior synonym of exiguum: Sharaf, Collingwood, et al., 2015: 52.
 * dryhimi. Monomorium dryhimi Aldawood & Sharaf, 2011: 49, figs. 1-7 (w.) SAUDI ARABIA.
 * Junior synonym of exiguum: Sharaf et al., 2018: 12.
 * faurei. Monomorium (Mitara) faurei Santschi, 1915c: 260, fig. 10 (w.) GABON.
 * Combination in M. (Lampromyrmex): Wheeler, W.M. 1922a: 876.
 * Junior synonym of exiguum: Bolton, 1987: 388.
 * flavescens. Monomorium (Mitara) exiguum r. flavescens Forel, 1916: 418 (w.) DEMOCRATIC REPUBLIC OF CONGO.
 * Junior synonym of exiguum: Bolton, 1987: 388.
 * minutissimum. Monomorium (Lampromyrmex) minutissimum Santschi, 1937d: 227, figs. 27, 28 (w.) ANGOLA.
 * Junior synonym of mictile: Bolton, 1987: 401; of exiguum: Heterick, 2006: 116.
 * montanum. Monomorium montanum Collingwood & Agosti, 1996: 350, fig. 24 (w.) SAUDI ARABIA.
 * Junior synonym of exiguum: Sharaf et al., 2018: 12.
 * baushare. Monomorium baushare Collingwood & Agosti, 1996: 342 (w.) OMAN.
 * Junior synonym of exiguum: Sharaf et al., 2017: 343.
 * qarahe. Monomorium qarahe Collingwood & Agosti, 1996: 353 (w.) SAUDI ARABIA.
 * Junior synonym of exiguum: Sharaf et al., 2017: 343.

Bolton (1987) - Without doubt the name exiguum, as presently constituted, conceals more than one valid species, but a very detailed analysis of much more material than is currently available will be necessary to split up the mass. Particularly interesting is the occurrence of both alate and apterous females among some Ghanaian samples. Almost certainly this indicates that two species are present in Ghana and workers associated with the apterous females closely match the type-series of Monomroium flavescens. Unfortunately females from the rest of the range are utterly unknown so no comparisons can be accurately made. The species closest to exiguum as defined here is Monomorium vaguum, but this is easily distinguished by the presence in the latter of a conspicuous clump of 4 or more pairs of hairs on the pronotum.

Worker
Heterick (2006) - Lectotype (M. exiguum): HML 0.93 HL 0.36 HW 0.28 CeI 78 SL 0.22 SI 79 PW 0.18. Lectotype (Monomorium exiguum bulawayense): HML 1.00 HL 0.39 HW 0.32 CeI 81 SL 0.26 SI 83 PW 0.20. Lectotype (Monomorium faurei): HML 0.88 HL 0.35 HW 0.29 CeI 83 SL 0.22 SI 76 PW 0.18. Lectotype (Monomorium exiguum flavescens): HML 0.89 HL 0.36 HW 0.30 CeI 82 SL 0.22 SI 75 PW 0.18. Lectotype (Monomorium minutissimum): No measurements taken as lectotype is headless.

HML 0.79–0.97; HL 0.33–0.39 HW 0.26–0.29 CeI 73–81 SL 0.22–0.26 SI 81–93 PW 0.16–0.20 (n=20).

HEAD: Head rectangular, vertex planar or weakly concave; frons shining and smooth except for piliferous pits; pilosity of frons a mixture of well-spaced, distinctly longer erect and semi-erect setae interspersed with shorter decumbent setae or setulae. Eye moderate, eye width 1–1.5× greatest width of antennal scape; (in full-face view) eyes set below midpoint of head capsule; (viewed in profile) eyes set around midline of head capsule; eye elliptical, curvature of inner eye margin may be more pronounced than that of its outer margin. Antennal segments 11; antennal club three-segmented. Clypeal carinae weakly to strongly defined; anteromedian clypeal margin straight; paraclypeal setae moderately long and fine, curved; posteromedian clypeal margin approximately level with antennal fossae. Anterior tentorial pits situated nearer antennal fossae than mandibular insertions. Frontal lobes straight, parallel. Psammophore absent. Palp formula 2,2. Mandibular teeth three, plus minute, basal denticle or angle; mandibles with sub-parallel inner and outer margins, smooth (except for piliferous pits); masticatory margin of mandibles approximately vertical or weakly oblique; basal tooth a small to minute denticle or angle, much smaller than t3 (four teeth present).

MESOSOMA: Promesonotum shining and mainly smooth, vestigial striolae, if present, confined to lower anterior mesopleuron; (viewed in profile) anterior promesonotum smoothly rounded, thereafter more-or-less flattened; promesonotum on same plane as propodeum, promesonotal setae seven to twelve; standing promesonotal setae a mixture of well-spaced, distinctly longer, erect and semi-erect setae which are curved distally and often paired, interspersed with much shorter, incurved, decumbent setae; appressed promesonotal setulae few, mainly on sides of promesonotum. Metanotal groove strongly impressed, with distinct transverse costulae, or, metanotal groove vestigial. Propodeum shining and smooth, with a few weak striolae on metapleuron; propodeal dorsum convex; propodeum always smoothly rounded; standing propodeal setae consisting of one prominent pair anteriad, with other shorter setae very sparse or absent; appressed propodeal setulae very sparse or absent; propodeal spiracle equidistant from metanotal groove and declivitous face of propodeum. Vestibule of propodeal spiracle absent or not visible. Propodeal lobes present as vestigial flanges or small strips of cuticle only.

PETIOLE AND POSTPETIOLE: Petiolar spiracle lateral and situated within anterior sector of petiolar node; node (viewed in profile) conical, vertex tapered; appearance of node shining and smooth throughout; ratio of greatest node breadth (viewed from front) to greatest node width (viewed in profile) about 1:1; anteroventral petiolar process absent or vestigial; ventral petiolar lobe present; height ratio of petiole to postpetiole between 3:2 and 4:3; height–length ratio of postpetiole about 1:1; postpetiole shining and smooth; postpetiolar sternite without anterior lip or carina, or this structure vestigial.

GASTER: Pilosity of first gastral tergite consisting of well-spaced, erect and semi-erect setae interspersed with a few appressed setulae.

GENERAL CHARACTERS: Color variable, pale yellow to brown. Worker caste monomorphic.

Queen
Heterick (2006) - HML 1.55–2.00 HL 0.45–0.55 HW 0.39–0.54 CeI 83–98 SL 0.34–0.42 SI 75–90 PW 0.28–0.55 (n=19).

HEAD: Head rectangular; vertex weakly concave or planar; frons shining and smooth except for piliferous pits; pilosity of frons a mixture of well-spaced, distinctly longer erect and semi-erect setae interspersed with shorter setae or setulae, which are decumbent or appressed, longer setae thickest on vertex. Eye elliptical, margin sometimes shallowly concave; (in full-face view) eyes set at about midpoint of head capsule; (viewed in profile) eyes set posteriad of midline of head capsule.

MESOSOMA: Anterior mesoscutum smoothly rounded, thereafter more-or-less flattened; pronotum, mesoscutum and mesopleuron shining and mainly smooth, vestigial striolae, if present, confined to anterior katepisternum; length-width ratio of mesoscutum and scutellum combined between 2:1 and 3:2; axillae contiguous, or nearly so; standing pronotal/mesoscutal setae a mixture of well-spaced, distinctly longer, erect and semi-erect setae which are curved distally, interspersed with much shorter, incurved, decumbent setae; appressed pronotal, mescoscutal and mesopleural setulae few, mainly on sides of pronotum and mesopleuron. Propodeum shining and smooth, with a few weak striolae on metapleuron; propodeum smoothly rounded or with indistinct angle; propodeal dorsum convex; standing propodeal setae consisting of up to a dozen or more longer erect and shorter sub-erect setae; appressed propodeal setulae very sparse or absent; propodeal spiracle nearer metanotal groove than declivitous face of propodeum; propodeal lobes present as vestigial flanges only, or absent.

WING: Wing not seen (queens dealated).

PETIOLE AND POSTPETIOLE: Petiolar spiracle lateral and situated slightly anteriad of petiolar node; node (viewed in profile) cuneate, vertex tapered; appearance of node shining, with vestigial sculpture; ratio of greatest node breadth (viewed from front) to greatest node width (viewed in profile) between 2:1 and 1:1; anteroventral petiolar process present as a thin flange tapering posteriad; height ratio of petiole to postpetiole between 4:3 and 1:1; height–length ratio of postpetiole between 4:3 and 1:1; postpetiole shining and weakly striolate posteriad; postpetiole shining and smooth; postpetiolar sternite without anterior lip or carina, or this structure vestigial (NB. May be confused with rear margin of postpetiolar sternite, which does project as a spur, length of sternite being much reduced).

GASTER: Pilosity of first gastral tergite consisting of well-spaced, erect and semi-erect setae interspersed with a few appressed setulae.

GENERAL CHARACTERS: Color yellowish-brown. Brachypterous alates not seen. Ergatoid or worker-female intercastes seen.

Male
Heterick (2006) - HML 1.37–1.96 HL 0.41–0.51 HW 0.42–0.48 CeI 102–116 SL 0.10–0.19 SI 24–34 PW 0.44–0.66 (n=11).

HEAD: (In full-face view) head width-mesosoma width ratio between 1:1 and 3:4; frons finely micropunctate. Compound eyes protuberant and elliptical tending to elongate; margin of compound eye clearly separated from posterior margin of clypeus. Ocelli turreted. Ratio of length of first funicular segment of antenna to second funicular segment between 1:1 and 3:4. Maximum number of mandibular teeth and denticles three.

MESOSOMA: Mesoscutum broadly convex; pronotum and mesoscutum shining and mainly smooth, vestigial striolae, if present, confined to lower anterior mesopleuron; parapsidal furrows vestigial or absent; notauli absent; axillae widely separated (i.e., by width of at least one axilla), axilla fused with scutellum to narrowly separated (i.e., less than width of one axilla).

WING: Wing veins predominantly depigmented, with distal segments reduced to vestigial lines; vein m–cu absent; vein cu–a absent.

PETIOLE AND POSTPETIOLE: Petiolar spiracle lateral and situated slightly anteriad of petiolar node; node (viewed in profile) conical, vertex tapered, appearance of node shining and smooth; ratio of greatest node breadth (viewed from front) to greatest node width (viewed in profile) between 4:3 and 1:1; anteroventral petiolar process absent or vestigial; height ratio of petiole to postpetiole between 1:1 and 3:4; height–length ratio of postpetiole between 2:1 and 4:3; postpetiole shining, with vestigial sculpture.

GASTER: Pilosity of first gastral tergite consisting of well-spaced, semi-erect setae interspersed with a few appressed setulae.

GENERAL CHARACTERS: Color light to medium brown, appendages pure brown to off-white

Type Material
Heterick (2006) - (lectotype here designated), ETHIOPIA: (locality on label now illegible, but given as ‘Südabessinien’ in Bolton 1987).

LECTOTYPE: worker, Ethiopia, Ilg. In view of the variability, particularly in color, that led researchers to erect new ‘varieties’ for this species, a lectotype has been chosen for M. exiguum that fixes the species name for populations with dark, longer-headed specimens that have the characteristics mentioned in the original description. This particular specimen has been glued in the normal way, dorsal surface uppermost. PARALECTOTYPE: worker, same data as lectotype, here designated for a specimen that has been pointed on the same pin as the lectotype and glued on its back. This specimen has been repinned with photocopies of the original labels (MHNG).

Monomorium dryhimi
 * Holotype worker. SAUDI ARABIA, Al Bahah province, Amadan forest, Al Mandaq governorate, 20°12'N, 41°13'E, 1881 m.a.s.l. 19.V.2010 (M. R. Sharaf & A. S. Aldawood Leg.); King Saud Museum of Arthropods, College of Food and Agriculture Sciences, King Saud University, Riyadh, Kingdom of Saudi Arabia.
 * Paratypes. 27 workers, same locality and data as holotype; 1 deposited in the Muséum ďHistoire Naturelle, Geneva, Switzerland (Dr Bernhard Merz); 1 in Naturhistorisches Museum, Basel, Switzerland (Mrs. Isabelle Zürcher-Pfander); 1 in California Academy of Science (Dr Brian Fisher); 1 in World Museum Liverpool, Liverpool, U.K (Dr Guy Knight), 1 in The Natural History Museum, London (Mr. Barry Bolton); 15 workers, SAUDI ARABIA, Elqamh park, Belgershi, Al Bahah, 17.V.2010 (M. R. Sharaf & A. S. Aldawood Leg.) These paratypes are in the King Saud Museum of Arthropods, King Saud University, Riyadh, Saudi Arabia.

References based on Global Ant Biodiversity Informatics

 * Aldawood S. A. and Sharaf, M. R. 2011. Monomorium dryhimi sp. n., a new ant species (Hymenoptera, Formicidae) of the M. monomorium group from Saudi Arabia, with a key to the Arabian Monomorium monomorium-group. ZooKeys 106: 47-54
 * Bakr R. F. A., H. H. Fadl, R. M. Badawy, and M. R. Sharaf. 2007. Myrmecophile insects associated with some ant species (Hymenoptera : Formicidae )in Egypt. The second international conference of economic entomology (Entomological Society of Egypt) ,Cairo, Egypt, 8-11 December, (1): 205-233.
 * 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.
 * 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.
 * Bernard F. 1950. Contribution à l'étude de l'Aïr. Hyménoptères Formicidae. Mém. Inst. Fr. Afr. Noire 10: 284-294.
 * Bolton B. 1987. A review of the Solenopsis genus-group and revision of Afrotropical Monomorium Mayr (Hymenoptera: Formicidae). Bulletin of the British Museum (Natural History). Entomology 54: 263-452.
 * Borowiec L. 2014. Catalogue of ants of Europe, the Mediterranean Basin and adjacent regions (Hymenoptera: Formicidae). Genus (Wroclaw) 25(1-2): 1-340.
 * 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.
 * Collingwood C.A., D.Agosti, M.R. Sharaf, and A. van Harten. 2011. Order Hymenoptera, family Formicidae. Arthropod fauna of the UAE, 4: 405474
 * Collingwood, C. A. and D. Agosti. 1996. Formicidae (Insects: Hymenoptera) of Saudi Arabia (Part 2) Fauna of Saudi Arabia 15: 300-385.
 * Collingwood, C. A., and Donat Agosti. "Formicidae (Insecta: Hymenoptera) of Saudi Arabia (Part 2)." Fauna of Saudi Arabia 15 (1996): 300-385.
 * El-Hawagry M. S., M. W. Khalil, M. R. Sharaf, H. H. Fadl, and A. S. Aldawood. 2013. A preliminary study on the insect fauna of Al-Baha Province, Saudi Arabia, with descriptions of two new species. ZooKeys 274: 188. doi:10.3897/zookeys.274.4529
 * Ettershank G. 1966. A generic revision of the world Myrmicinae related to Solenopsis and Pheidologeton (Hymenoptera: Formicidae). Aust. J. Zool. 14: 73-171.
 * Finzi B. 1939. Materiali zoologici dell'Eritrea raccolti da G. Müller durante la spedizione dell'Istituto Sieroterapico Milanese e conservati al Museo di Trieste. Parte III. Hymenoptera: Formicidae. Atti del Museo Civico di Storia Naturale di Trieste 14: 153-168.
 * Fisher B. L. 2004. Diversity patterns of ants (Hymenoptera: Formicidae) along an elevational gradient on Monts Doudou in southwestern Gabon. Memoirs of the California Academy of Sciences 28: 269-286.
 * Forel A. 1913. Quelques fourmis du Musée du Congo Belge (1). Annales de la Société Entomologique de Belgique 57: 347-359.
 * Forel A. 1916. Fourmis du Congo et d'autres provenances récoltées par MM. Hermann Kohl, Luja, Mayné, etc. Revue Suisse de Zoologie 24: 397-460.
 * Heterick B. 2006. A Revision of the Malagasy Ants Belonging to Genus Monomorium Mayr, 1855 (Hymenoptera: Formicidae). Proceeding of the California Academy of Sciences (PCAS) 57: 69-202
 * IZIKO South Africa Museum Collection
 * Kouakou L. M. M., K. Yeo, K. Ouattara, W. Dekoninck, T. Delsinne, and S. Konate. 2018. Investigating urban ant community (Hymenoptera: Formicidae) in port cities and in major towns along the border in Côte d’Ivoire: a rapid assessment to detect potential introduced invasive ant species. Journal of Animal and Plant Sciences 36(1): 5793-5811.
 * Kouakou L. M. M., W. Dekoninck, M. Kone, T. Delsinne, K. Yeo, K. Ouattara, and S. Konate. 2018. Diversity and distribution of introduced and potentially invasive ant species from the three main ecoregions of Côte d’Ivoire (West Africa). Belgian Journal of Zoology 148 (1): 83–103.
 * Ravelomanana A., and B. L. Fisher. 2013. Diversity of ants in burned and unburned grassland, and dry deciduous forest in the Beanka Reserve, Melaky Region, western Madagascar. Malagasy Nature 7: 171-183.
 * Robertson H. G. 2000. Formicidae (Hymenoptera: Vespoidea). Cimbebasia Memoir 9: 371-382.
 * Samways M. J. 1990. Species temporal variability: epigaeic ant assemblages and management for abundance and scarcity. Oecologia 84: 482-490.
 * Santschi F. 1915. Nouvelles fourmis d'Afrique. Annales de la Société Entomologique de France 84: 244-282.
 * Santschi F. 1937. Résultats de la Mission scientifique suisse en Angola (2me voyage) 1932-1933. Fourmis angolaises. Revue Suisse de Zoologie. 44: 211-250.
 * Sharaf M. R., B. L. Fisher, H. M. Al Dhafer, A. Polaszek, and A. S. Aldawood. 2018. Additions to the ant fauna (Hymenoptera: Formicidae) of Oman: an updated list, new records and a description of two new species. Asian Myrmecology 10: e010004
 * Sharaf M. R., C. A. Collingwood, H. M. Al Dhafer, M. S. Al mutairi, and A. S. Aldawood. 2015. New synonyms of two Arabian ants of the genus MonomoriumMayr, 1855 (Hymenoptera, Formicidae). ZooKeys 505: 51–58.
 * Sharaf M. R., H. M. Al Dhafer, and S. A. Aldawood. 2014. First record of the myrmicine ant genus Meranoplus Smith, 1853 (Hymenoptera: Formicidae) from the Arabian Peninsula with description of a new species and notes on the zoogeography of Southwestern Kingdom Saudi Arabia. PLoS ONE 9(11): e111298 (doi:10.1371/journal.pone.0111298).
 * Sharaf M., H. M. Al Dhafer, A. S. Aldawood, and F. Hita Garcia. 2018. Ants of the Monomorium monomorium species-group (Hymenoptera: Formicidae) in the Arabian Peninsula with description of a new species from southwestern Saudi Arabia. PeerJ 6:e4277; DOI 10.7717/peerj.4277
 * Stephens S. S., P. B. Bosu, and M. R. Wager. 2016. Effect of overstory tree species diversity and composition on ground foraging ants (Hymenoptera: Formicidae) in timber plantations in Ghana. International Journal of Biodiversity Science, Ecosystem Services & management 12(1-2): 96-107.
 * Taylor B., N. Agoinon, A. Sinzogan, A. Adandonon, Y. N'Da Kouagou, S. Bello, R. Wargui, F. Anato, I. Ouagoussounon, H. Houngbo, S. Tchibozo, R. Todjhounde, and J. F. Vayssieres. 2018. Records of ants (Hymenoptera: Formicidae) from the Republic of Benin, with particular reference to the mango farm ecosystem. Journal of Insect Biodiversity 8(1): 006–029.
 * Wheeler W. M. 1922. Ants of the American Museum Congo expedition. A contribution to the myrmecology of Africa. VIII. A synonymic list of the ants of the Ethiopian region. Bulletin of the American Museum of Natural History 45: 711-1004