Bothroponera ilgii

Specimens have been collected on and under trunks of Acacia trees, in litter, under stones and on ground of the Acacia woodland and on a rotting eland skull. In the forests, workers were observed foraging, tandem running, scavenging in litter and excavating under Acacia trees and in the soil under stones. (Joma and Mackay 2017)

Identification
Joma and Mackay (2017) - A member of the Bothroponera sulcata species complex. Worker The worker of Bothroponera ilgii can be characterized by the narrowed mandibles that have about 7-9 teeth, which alternate in size and the mandibles that are covered with fine striae and large scattered elongate punctures. The anterior medial margin of the clypeus is convex with a medial raised area that has a longitudinal narrowed shiny groove. The posteropropodeum is slightly sloping and forms a broadly curved angle with the dorsopropodeum.

The head and dorsum of the pronotum, petiole and postpetiole are roughly sculptured with very few scattered punctulae. The anterior face of the petiole (seen from above) is rounded and the posterior face is slightly concave (seen from the side). The entire body is covered with a fine pubescence.

The worker of B. ilgii is quite similar to that of B. crassa and B. notaula, but the total length of B. ilgii is slightly longer (8.35 - 9.40 mm). The medial raised area of the clypeus is nearly always completely convex in B. crassa similar to that of B. ilgii, but with some exceptions in both species. There are slight grooves or partial depressions on the anterior raised area of the clypeus of B. crassa and B. ilgii. The medial raised area of the clypeus of B. notaula forms a longitudinal shiny smooth wide and shallow groove. This difference is based on the type series of B. ilgii, B. notaula and B. crassa, which is might be variable in other specimens.

The workers of B. soror are also nearly identical to those of B. ilgii, but there are some specific differences. The total length of B. soror is slightly greater (8.65 - 11.10 mm, compared to 8.35 - 9.40 in B. ilgii). The margins of the lateropropodeum of B. soror are rough and angular, while it has sharp posterior margins and is slightly chunkier in B. ilgii. The posteropropodeum is slightly concave and strongly sloped posteriorly in B. soror, whereas it is straight with a slight depression at the dorsopropodeum (seen from above) in B. ilgii.

The longitudinal depression forms a groove on the medial raised area of the clypeus of B. ilgii, which separates it from B. crassa. The single medial raised area of the clypeus of B. soror forms a shiny, striated area without a longitudinal depression The head measurements are larger in B. soror (length is 1.70 - 1.90 and width is 1.50 - 1.65) than in B. ilgii.

Male The head of the B. ilgii male is nearly round, excluding the mandibles. The ocelli are relatively small. The scape is twice as long as the pedicel (first funicular segment), shorter and thicker than the second funicular segment. The pronotum is square laterally and rounded anteriorly. The notauli are absent on the dorsum of the scutum. The scutellum is subtriangular and elevated above the level of the mesosoma as seen in lateral view. The metanotum is raised between the scutellum and propodeum. The metanepisternum is well developed and distinguished from the propodeum and mesopleuron while the metakatepisternum is narrowed and poorly defined.

The dorsopropodeum is gradually sloped posteriorly to the insertion of the petiole. The petiole, postpetiole and the remainder of the gastral segments are missing.

The color of the entire body is mostly light brown to medium brown.

The male specimen of Bothroponera ilgii can be compared with the other known males of the Bothroponera sulcata species complex including Bothroponera crassa, Bothroponera kruegeri, Bothroponera silvestrii and Bothroponera soror. The total length of the B. ilgii type male is unavailable because the only specimen (paralectotype) is missing both the petiole and the gaster, The total lengths of the males of B. soror (6.45 - 7.45 mm), B. crassa (5.90 - 7.50 mm), B. kruegeri (10.25 mm), Bothroponera notaula (5.60 - 7.90 mm), Bothroponera ryderae (6.45 mm) and Bothroponera silvestrii (4.70 - 5.10 mm), indicate that the largest species is B. kruegeri and the smallest is B. silvestrii, but the other species tend to overlap in their total lengths. The notauli are absent in B. crassa and B. ilgii while they are present in B. soror, B. notaula, B. ryderae, B. silvestrii and the male of B. kruegeri has weak evidence of notauli. The ocelli are small in B. ilgii, B. soror, B. silvestrii and B. ryderae, but they are large in B. crassa, B. kruegeri and B. notaula. The pronotum, scutum, scutellum and propodeum of all of the species are roughly sculptured. Bothroponera soror can be separated, as there are a few scattered punctures on most surfaces, petiole and postpetiole while the 4th to 7th abdominal segments are less sculptured or even smooth. The pronotum, scutum, scutellum, propodeum, petiole and postpetiole of B. crassa and B. ilgii are roughly sculptured. The 4th to 7th abdominal segments are smooth without punctures in Bothroponera soror, B. crassa and B. ilgii. The sculpture of B. notaula, B. ryderae and B. silvestrii are similar as it is usually rough and moderately shiny and without punctures on the head, pronotum, scutum, scutellum, metanotum, propodeum, mesopleuron and petiole. Conversely, the postpetiole and 4th to 7th absominal segments are smooth and shiny. The dorsopropodeum slopes gradually posteriorly in B. crassa and B. ilgii similar to that in B. kruegeri, whereas the dorsopropodeum is strongly curved into the posteropropodeum in B. soror. The ocelli are large in B. crassa, but they are small in both B. soror and B. ilgii; likewise, the ocelli are small in B. silvestrii and B. ryderae.

Bothroponera ancilla, B. soror, B. silvestrii, B. ryderae, Bothroponera pilosuperficia can be directly separated because of the structure of the dorsopropodeum with the posteropropodeum. The posteropropodeum (side view) is semi-vertical (strongly sloping posteriorly) in B. ancilla, B. soror, B. silvestrii, B. ryderae and B. pilosuperficia while the posteropropodeum of the other species including B. crassa, B. ilgii, B. notaula, B. silvestrii and B. kruegeri gradually slopes posteriorly.

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

Nomenclature

 * . Pachycondyla (Bothroponera) crassa var. ilgii Forel, 1910c: 244 (w.) ETHIOPIA.
 * Combination in Pachycondyla: Brown, in Bolton, 1995b: 306;
 * combination in Bothroponera: Schmidt, C.A. & Shattuck, 2014: 77.
 * Subspecies of crassa: Emery, 1911d: 77; Santschi, 1914b: 50; Wheeler, W.M. 1922a: 770; Bolton, 1995b: 306.
 * Synonym of crassior: Joma & Mackay, 2017: 17.
 * [Note: Joma & Mackay, 2017: 17, give crassior as senior synonym, but ilgii has priority.]
 * Senior synonym of gamzea Özdikmen, 2010c: 994 (unnecessary replacement name for ilgii Forel, 1910c: 244).
 * gamzea. Pachycondyla crassa gamzea Özdikmen, 2010c: 994.
 * Unnecessary replacement name for Pachycondyla crassa ilgii Forel, 1910c: 244.
 * Subspecies of crassa: Hita Garcia, et al. 2013: 220.
 * Junior synonym of crassior: Joma & Mackay, 2017: 17 (error).
 * [Note: ilgii has priority over crassior, therefore gamzea is a junior synonym of ilgii.]
 * Junior synonym of ilgii Forel, 1910c: 244.

Worker
Joma and Mackay (2017) - (n=25), HL 1.65 - 1.90, HW 1.35 - 1.60, ML 1.05 - 1.15, EW 0.30 - 0.35, EL 0.40 - 0.45, SL 1.35 - 1.55, FL 2.10 - 2.30, WL 2.15 - 2.85, WPL 2.70 - 3.50, PL 0.65 - 0.75, PW 0.90 - 0.95, PH 1.15 - 1.30, CI 81.81 - 84.21, OI 28.12 - 29.62, Mandl 60.52 - 63.63, SI 96.87 - 100.00, Peti 126.66 - 138.46. The measurements of B. gamzea (synonym of B. ilgii): HL 1.70 - 1.85, HW 1.40 - 1.55, ML 1.00, EW 0.30 - 0.35, EL 0.40, SL 1.40, FL 2.25, WL 2.60 - 2.65, WPL 3.25 - 3.30, PL 0.65 - 0.70, PW 0.85 - 0.90, PH 1.20 - 1.15, CI 82.35 - 83.78, OI 25.80 - 28.57, Mandl 5.40 - 5.88, SI 90.32 - 100.00, Peti 128.57 - 130.76. Total length 8.35 - 9.40 mm; head excluding mandibles nearly quadrate; eye diameter slightly longer than malar area length, length of malar space on side of head 0.20 - 0.25 mm, length from upper edge of eye to top of posterior lobe 0.80 - 0.90 mm; scape extends slightly past posterior lateral corner of head; pronotal humerus rounded anteriorly; apex of petiole slightly higher than level of postpetiole and dorsopropodeum. Dorsum of pronotum, and propodeum covered with short (0.15 mm) erect scattered silver hairs; dorsum of petiole and postpetiole covered with longer (0.20 mm) erect silver hairs; long (0.25 mm) erect silver hairs arranged on edges of posteropropodeum; head covered with short (less than 0.10 mm) erect hairs; ventral surface of head covered with moderately long (0.15 - 0.35 mm) erect hairs; entire body covered with fine pubescence. Body black, dark brown or reddish brown; mandibles, head dark brown; legs and mandibles reddish brown. In some specimens, tibia and scape dark brown, tarsus and funiculus light brown.

Male
Joma and Mackay (2017) - (n=1), HL 1.10, HW 0.80, ML 0.30, EW 0.40, EL 0.70, SL 0.30, FL 4.80, WL 2.30. The petiole and the gaster are missing. CI 72.72, OI 87.50, Mandl 27.27, SI 37.50. Total length unknown; eyes large, cover most of sides of head, distance between eyes (0.70 mm) from upper inner sides, medial ocellus width 0.15 mm; scape shorter (0.35 mm) and thicker than first funicular segment, twice length of pedicel (0.15 mm); pronotum square laterally and rounded anteriorly; scutum rounded; notauli absent on dorsum of scutum; scutellum triangular in dorsal view and elevated in side view; metanotum raised between scutellum and propodeum; metaepisternum well developed and separated from propodeum and mesopleuron by suture; dorsopropodeum gradually sloping down posteriorly to insertion of petiole; pronotum, scutum, scutellum, propodeum roughly sculptured; fine short dense hairs cover entire body; moderately long hairs (0.10-0.15 mm) scattered on dorsum of scutellum, metanotum, propodeum, on suture between pronotum and scutum; hairs on dorsum of scutellum longer (0.20 - 0.25 mm) and denser than on other parts; ventral surface of head with moderately long (0.20 mm) erect hairs; color mostly light brown to medium brown and yellowish.

Type Material
Joma and Mackay (2017) - Pachycondyla (Bothroponera ) crassa var. ilgi Forel, Ethiopia: Harar ilg, 9°30'0" 41°30'0" E, Forel ded. 1922 (1 w paratypus [designator not listed], ZMHU).

References based on Global Ant Biodiversity Informatics

 * Emery C. 1911. Hymenoptera. Fam. Formicidae. Subfam. Ponerinae. Genera Insectorum 118: 1-125.
 * Garcia F.H., Wiesel E. and Fischer G. 2013.The Ants of Kenya (Hymenoptera: Formicidae)Faunal Overview, First Species Checklist, Bibliography, Accounts for All Genera, and Discussion on Taxonomy and Zoogeography. Journal of East African Natural History, 101(2): 127-222
 * Joma A. M. A., and W. P. MacKay. 2017. Revision of the African ants of the Bothroponera sulcata species complex (Hymenoptera: Formicidae: Ponerinae). Transactions of the American Entomological Society, 143(1): 7-71.
 * 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.
 * Prins A. J. 1963. A list of the ants collected in the Kruger National Park with notes on their distribution. Koedoe 6: 91-108.
 * Prins A. J. 1964. Revised list of the ants collected in the Kruger National Park. Koedoe 7: 77-93.
 * Santschi F. 1930. Description de Formicides éthiopiens nouveaux ou peu connus. V. Bulletin et Annales de la Société Entomologique de Belgique 70: 49-77.
 * Santschi F. 1930. Trois notes myrmécologiques. Bulletin et Annales de la Société Entomologique de Belgique. 70: 263-270.
 * 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