Bothroponera crassa

The few collections of B. crassa indicate that it is neither common nor widespread in Africa. Ten males were collected from Kenya, Laikipia District, Mpala Research Centre at night (8:30 to 9:30 pm) where they were flying at lights. (Joma and Mackay 2017)

Identification
Joma and Mackay (2017) - A member of the Bothroponera sulcata species complex. Worker The Bothroponera crassa workers are characterized by being relatively small (total length 6.0 - 8.8 mm), having the anterior medial margin of the clypeus convex with a smooth and shiny medial raised area, but without a clypeal carina (this raised area varies among B. crassa individuals and they may have a small depressed area anteriorly or even a short trough).

The head, pronotum, petiole and postpetiole are roughly sculptured with a few scattered punctures, but not on the 4th to 7th abdominal segments. The mandibles are smooth to striate with scattered punctures. The pronotal humerus is rounded anteriorly. The lateropropodeum is compressed laterally to form a slender lateropropodeum with concave sides as seen from above. The posteropropodeum usually declines gradually. The apex of the petiole is nearly flat with a straight anterior face while it is slightly concave posteriorly (side view). The apex of the petiole is slightly higher than the postpetiole and the dorsopropodeum.

It is difficult to separate B. crassa from Bothroponera ilgii, Bothroponera notaula, Bothroponera silvestrii and Bothroponera kruegeri because these species have similar dorsopropodea and posteropropodea. The total length of the worker of B. crassa ranges from 6.00 - 8.80 mm, which overlaps that of B. ilgii (8.35 - 9.40 mm), B. notaula (7.60 mm), and B. silvestrii (5.25 - 7.05 mm). The obvious characters that can separate those species are the structure of the clypeus and the form of the propodeum. The clypeus of B. crassa always has a smooth and shiny medial raised area, but without a groove in the two type specimens or with no more than a partial clypeal groove in other three specimens from Kenya. On the other hand, the type specimens of B. ilgii have a complete longitudinal shiny raised strip on the anterior medial area of the clypeus that forms a narrowed groove, and this area has a partial groove in the specimens from Kenya, Tanzania and Ethiopia. The anterior medial area of the clypeus of B. notaula forms a shiny smooth longitudinal strip with a clear wide groove. The other character is the structure of the lateropropodeum. This area is laterally compressed in B. crassa, including the three specimens from Kenya, apparently for the positioning of the metafemora (best seen from above). This character separates B. crassa from all of the others in the complex including B. ilgii, B. kruegeri and the B. notaula. Conversely, B. ilgii has a convex lateropropodeum. Finally, the propodeum is subquadrate and angulate between the faces of B. crassa, while it is mostly rounded (broadly curved) in B. ilgii.

Male The head of the B. crassa male is suborbiculate, excluding the mandibles and the mouthparts. The ocelli are relatively large. The notauli are absent on the dorsum of the scutum. The metanepisternum is well developed and distinguished from the propodeum and mesopleuron with a suture, while the metakatepisternum is narrowed and poorly defined. The dorsopropodeum is gradually sloped posteriorly to reach the insertion of the petiole at the lowest medial point of the propodeum. The petiole is small; its width is less than that of the dorsopropodeum (seen from above) and the height is less than the postpetiolar height and with a bluntly rounded apex. The pronotum, scutum, scutellum, propodeum, petiole and postpetiole are roughly sculptured. The postpetiole is rounded anteriorly.

The male of Bothroponera crassa is similar to other known males of the Bothroponera sulcata complex, including B. ilgii, B. kruegeri, B. notaula, Bothroponera ryderae, B. silvestrii, and Bothroponera soror. The notauli are absent in B. crassa and B. ilgii while they are present in B. soror, B. notaula, B. ryderae and B. silvestrii. The notauli in B. kruegeri are not well defined. The pronotum, scutum, scutellum and propodeum are roughly sculptured with a few scattered punctures on surface of B. soror. The petiole and postpetiole with the rest of the gastral segments of B. soror are less sculptured (rough) than they are in B. crassa. The pronotum, scutum, scutellum and propodeum of B. ilgii and B. crassa are rough (not punctuated). The head, pronotum, scutum, scutellum, metanotum, propodeum and petiole of males of B. silvestrii, B. notaula, B. ryderae and B. kruegeri are rough, but shiny while the postpetiole and 4th to 7th abdominal segments are mostly smooth and shiny. The petiole and postpetiole with the rest of gastral segments of B. crassa are similar to that of B. soror (rough); unfortunately, the gaster is missing in the only male specimen of B. ilgii; therefore, the measurement is missing in B. ilgii. The dorsopropodeum gradually slopes posteriorly in B. ilgii and B. crassa similarly to that in B. kruegeri whereas the dorsopropodeum is strongly curved nearly angulate posteriorly in B. soror. The dorsopropodeum in the males of B. notaula and B. ryderae is moderately broadly curved posteriorly to gradually reach the connection of the posteropropodeum with the petiole. The medial ocelli are large in B. crassa (0.20 - 0.25 mm), B. notaula (0.20 - 0.25 mm) and B. kruegeri (0.35 mm), which distinguish them from species with small medial ocelli including B. soror (0.10 - 0.15 mm), B. ryderae (0.16 mm), B. silvestrii (0.12 - 0.13 mm) and B. ilgii (0.17 mm).

Distribution
Eastern Africa (Eritrea, Kenya and Somalia).

Distribution based on Regional Taxon Lists
Afrotropical Region: Eritrea, Kenya, Somalia.

Nomenclature

 * . Ponera crassa Emery, 1877b: 366, fig. (w.) ERITREA.
 * Combination in Pachycondyla (Bothroponera): Emery, 1895a: 177; Emery, 1901a: 46;
 * combination in Pachycondyla: Brown, in Bolton, 1995b: 304;
 * combination in Bothroponera: Emery, 1892a: 111; Wheeler, W.M. 1922a: 73; Santschi, 1930a: 53; Schmidt, C.A. & Shattuck, 2014: 77.
 * Joma & Mackay, 2017: 14 (m.).
 * Status as species: Emery, 1892a: 111; Dalla Torre, 1893: 36; Forel, 1894b: 75; André, 1895a: 2; Emery, 1895a: 177; Forel, 1910c: 243; Emery, 1911d: 77; Forel, 1913h: 347; Santschi, 1914b: 50; Wheeler, W.M. 1922a: 73 (in key), 769; Finzi, 1939a: 154; Menozzi, 1939c: 98; Bernard, 1953b: 188; Bolton, 1995b: 304; Hita Garcia, et al. 2013: 220; Joma & Mackay, 2017: 14 (redescription); Madl, 2019: 16.

Worker
Joma and Mackay (2017) - (n=4), HL 1.45 - 1.75, HW 1.25 - 1.45, ML 0.75 - 0.95, EW 0.20 - 0.30, EL 0.30 - 0.40, SL 1.20 - 1.45, FL 2.00 - 2.40, WL 2.30 - 2.70, WPL 3.25 - 3.40, PL 0.60 - 0.75, PW 0.85 - 0.90, PH 1.05 - 1.15, CI 82.85 - 86.20, OI 24.00 - 27.58, Mandl 51.72 - 54.28, SI 96.00 - 100.00, Peti 120.00 - 141.66. Head quadrate, mandibles narrow with about 7-8 teeth, compound eyes relatively large; clypeus complex, dorsum shiny, smooth to striate with scattered punctures; scape extends slightly past posterior lateral corner of head; malar space length 0.25 length from upper edge of eye to edge of posterior lateral corner 0.85 mm; pronotal humerus rounded; dorsopropodeum slightly slopes posteriorly to form posteropropodeum; petiole slightly rounded from top, anterior face straight, slightly concave posteriorly, apex of petiole slightly higher than heights of postpetiole and dorsopropodeum; entire body covered with fine hairs; head covered with short erect hairs (less than 0.10 mm); hairs on ventral surface moderately long (0.15 - 0.35 Dorsum of pronotum, propodeum covered with short erect scattered hairs (0.15 mm); petiole postpetiole covered with moderately long erect (0.20 mm); long erect hairs (0.25 mm) arranged edges of posteropropodeum; color of entire body dark reddish-black or dark brownish; legs light brown or reddish brown; mandibles reddish brown.

Male
Joma and Mackay (2017) - (n=14), HL 1.05 - 1.20, HW 0.70 - 0.95, ML 0.25 - 0.35, EW 0.45 - 0.60, EL 0.60 - 0.80, SL 0.25 - 0.35, FL 5.05 - 5.55, WL 2.25 - 2.80, WPL 2.85 - 3.45, PL 0.60 - 0.65, PW 0.55 - 0.65, PH 0.75 - 0.85, CI 66.66 - 79.16, OI 84.21 - 85.71, Mandl 23.80 29.16, SI 35.71 - 36.84, Peti 91.66 - 100.00. length ranges from 5.90 - 7.50 mm; eyes large, cover most of sides of head, distance between 0.65 - 0.70 mm, medial ocellus width 0.20 - mm; scape shorter (0.30 mm) and thicker than second funicular segment, three times longer mm) than first funicular segment; pronotum laterally and rounded anteriorly; dorsum of rounded (side view); scutellum subtriangular elevated in lateral view; metanotum raised between scutellum and propodeum; mesopleuron divided anapleural sulcus to form infra katepisternum supra anepisternum; fine short (less than 0.05 dense hairs cover entire body; moderately long (0.15 - 0.25 mm) scattered on dorsum of scutellum, metanotum, propodeum, petiole, postpetiole, suture between pronotum and scutum; hairs dorsum of scutellum, petiole and ventral surface of postpetiole slightly denser than on other parts; ventral surface of head with moderately long mm) erect hairs; color mostly brown, light brown to yellowish.

Type Material
Eritrea: Bogos, Sciotel, 15°30’0’’ N; 38°14’0’’ E, O. Becaari 1870, type, Ponera crassa: Emery; syntype, Ponera crassa Emery 1877. Museo Civico di Genova (2w, lectotype and paralectotype, here designated, ).

The type specimens of B. crassa were collected from Sciotel in Eritrea, 15°30'0" N; 38°14'0" E, by Beccari; however, in several publications, the type specimens of B. crassa were reported from Ethiopia.

Determination Clarifications
Joma and Mackay (2017) - The majority of the specimens that were identified as B. crassa in many Museums and in previous studies are similar but are actually Bothroponera crassior (=Bothroponera ilgii) and Bothroponera soror.

References based on Global Ant Biodiversity Informatics

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 * André E. 1895. Formicides de l'Ogooué (Congo français). Rev. Entomol. (Caen) 14: 1-5.
 * Bernard F. 1953. La réserve naturelle intégrale du Mt Nimba. XI. Hyménoptères Formicidae. Mémoires de l'Institut Français d'Afrique Noire 19: 165-270.
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 * 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.
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 * Madl M. 2019. Notes on the ant fauna of Eritrea (Insecta: Hymenoptera: Formicidae): type specimens deposited in the Natural History Museum Vienna (Austria) and a preliminary checklist. Ann. Naturhist. Mus. Wien, B 121: 9-18.
 * Menozzi C. 1930. Formiche della Somalia italiana meridionale. Memorie della Società Entomologica Italiana. 9: 76-130.
 * Nsengimana V., K. A. Beth, F. Frederic, K. M. M. Lombart, D. Wouter, and N. Donat. 2018. Use of soil and litter ants (Hymenoptera: Formicidae) as biological indicators of soil quality under different land uses in Southern Rwanda. Environmental Entomology 47(6): 1394-1401.
 * 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. 1932. Formicides sud-africains. Pp. 381-392 in: Jeannel, R. (ed.) 1932. Société Entomologique de France. Livre du centenaire. Paris: Société Entomologique de France, xii + 729 pp.
 * Weber N. A. 1943. The ants of the Imatong Mountains, Anglo-Egyptian Sudan. Bulletin of the Museum of Comparative Zoology 93: 263-389.
 * 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