Bothroponera

Bothroponera is a moderately large genus, with more than 50 described species and subspecies. Relatively little is known about Bothroponera ecology and behavior. Some species (Bothroponera kruegeri, Bothroponera tesseronoda) have lost winged queens and mated workers reproduce instead ('gamergates').

Identification
Joma & Mackay (2013) - The genus is characterized by the narrowed, convex, and medially raised clypeus. The mandibles are triangular or narrowed with 6–9 teeth. The frontal lobes are rounded or semioval, divided by a well-developed frontal furrow. The pronotum of the worker lacks any evidence of a carina or shelf. The mesonotum is completely fused with the propodeum, and the notopropodeal suture is completely absent. The petiole is thick with a developed ventral process. The mesopleuron is not divided by an anapleural suture and is well separated from the metapleuron by the mesometapleural suture.

Schmidt and Shattuck (2014) - Bothroponera workers lack any obvious autapomorphies within the Ponerinae, and are therefore more difficult to diagnose than those of most ponerine genera. They can generally be distinguished by the following combination of characters: Body without a long dense golden pilosity, mesopleuron usually not divided by a transverse groove, metanotal groove obsolete, propodeal dorsum without spines or teeth, propodeal spiracles slit-shaped, petiole nodiform (and not semicircular in top view) and without posterodorsal spines or teeth, tergite of A3 without strong longitudinal striations, gaster with a strong constriction between A3 and A4, and metatibiae with two spurs. Species of Bothroponera (s.s.) also have strong sculpturing, large cordate frontal lobes, a broad propodeal dorsum, and a U-shaped cuticular lip posterior to the metapleural gland orifice, though members of the B. sulcata group lack these characters. Superficially, Bothroponera workers most closely resemble those of Phrynoponera and Pseudoneoponera, but they lack the bispinose propodeum, five-spined petiole, and unconstricted gaster of Phrynoponera and the shaggy pilosity, semicircular petiole, and longitudinally striate tergite A3 of Pseudoneoponera. Bothroponera can also be confused with Ectomomyrmex, though Bothroponera lacks the small eyes, angular sides of the head, divided mesopleuron (except in a few species), and weakly constricted gaster of Ectomomyrmex, and Asian Bothroponera species lack the strong sculpturing of Ectomomyrmex. The workers of Bothroponera (s.s.) also somewhat resemble the workers of Loboponera and Boloponera, given their stocky build, coarse sculpturing, large frontal lobes, obsolete mesopropodeal suture, broad propodeal dorsum, and nodiform petioles, but are readily separated from these genera by their metatibial spur formulae (two spurs versus one), propodeal spiracles (slit-shaped versus round), and metapleural gland orifice (opening posterolaterally versus laterally), among other characters.

Distribution
Bothroponera (sensu stricto) is restricted to Sub-Saharan Africa and Madagascar, while the B. sulcata group occurs from Sub-Saharan Africa through southern Asia to the Philippines. References in the literature to Australian Bothroponera species (and many Asian species as well) are actually references to Pseudoneoponera. (Schmidt and Shattuck 2014)

Biology
Relatively little is known about Bothroponera, and all studies of the ecology and behavior of these ants have focused on species in the B. sulcata group, so even less is known about the habits of Bothroponera (s.s.), with most information coming from anecdotal observations. Bothroponera sculpturata (as Bothroponera mlanjiensis) is reported to dwell in shady forest habitats and to nest in the ground (Arnold, 1946), collection data for several other species indicates that they also nest in the ground and are often collected in leaf litter, and Bothroponera pachyderma has been found nesting inside abandoned termitaries (Déjean et al., 1996), but otherwise ecological notes on Bothroponera (s.s.) are sorely lacking. At least some species feign death when disturbed (e.g., B. pachyderma; Wheeler, 1922b). B. pachyderma is reported to be a generalist predator (Déjean et al., 1999), but the prey preferences of other species are unknown. Some larger species, such as B. pachyderma, stridulate audibly when distressed (B. Bolton, pers. comm.).

Perhaps the best studied species of Bothroponera is Bothroponera tesseronoda, a South Asian member of the B. sulcata group. This species forms subterranean nests, with from 50 to 170 workers per colony (Jessen & Maschwitz, 1986). B. tesseronoda is apparently a generalist predator of arthropods, with termites making up a large portion of its diet (Shivashankar et al., 1995), though it is also known to visit extrafloral nectaries (Agarwal & Rastogi, 2008). Workers recruit nestmates to food sources and new nest sites via tandem running, which is initiated by mechanical stimulation and a colony-specific chemical trail derived from the entire body surface (Maschwitz & Mühlenberg, 1973; Maschwitz et al., 1974; Jessen & Maschwitz, 1985 and 1986; Maschwitz & Steghaus-Kovac, 1991). Nest entrances are marked with a colony-specific chemical cue, and foraging workers also employ chemical signaling while scouting a new area for food. Remarkably, individual workers can identify their own trails and show a preference for them over that of other individuals (Jessen & Maschwitz, 1986). Alarm pheromones and defensive secretions are produced in the mandibular glands, poison gland, and Dufour’s gland (Maschwitz et al., 1974).

An African species in the B. sulcata group, Bothroponera crassa, also uses tandem running for nestmate recruitment (Hölldobler & Wilson, 1990). Workers of another African member of the B. sulcata group, Bothroponera soror, use tandem running to recruit nestmates to large prey items or to groups of prey, but are also capable of recruiting nestmates from up to 150 mm away using a multicomponent mandibular gland secretion (Longhurst et al., 1980; Déjean, 1991). Arnold (1915) reports that workers of B. soror smell strongly like cockroaches; the mandibular gland secretions are possibly responsible for this. B. soror is a generalist predator of arthropods and a scavenger (Longhurst et al., 1980; Déjean et al., 1999). Déjean (1991) describes some behavioral adaptations of B. soror to termite predation, and Orivel & Déjean (2001) measured the toxicity of B. soror venom. Nests are typically located under stones or in termitaries (Déjean et al., 1996, 1997), and colonies are small with about two dozen workers (Arnold, 1915). Haskins (1941) found that B. soror queens display semi-claustral nest founding during which they forage outside the nest but also metabolize their flight muscles, and that they prefer to build nests in soil around rotting logs and even in the logs. Ground nesting is probably the rule for Bothroponera, though Bothroponera silvestrii has also been reported nesting in rotting wood (Taylor, 2008). Queenless but apparently self-sustaining populations of B. soror have been observed (Longhurst, 1977; Villet & Wildman, 1991).

An unusual member of the B. sulcata group is the South African species Bothroponera kruegeri, which has lost the queen caste and reproduces only via gamergate workers (Peeters & Crewe, 1986b). Colonies each have only a single gamergate, which is the only inseminated individual in the colony and the only individual with mature ovaries. Gamergates suppress the ovarian development of the other workers. This is apparently accomplished through chemical means, as no physical interactions between gamergates and non-gamergates have been observed (Wildman & Crewe, 1988; Villet & Wildman, 1991). Villet & Wildman (1991) examined division of labor in this species. In the population studied by Wildman & Crewe (1988), colony size ranged from 8 to 100 workers (mean = 43). This species is a generalized predator of arthropods (Wildman & Crewe, 1988) and nests in the ground (Villet & Wildman, 1991).

Discussions in the literature of foamy defensive secretions from the sting apparatus of Bothroponera (e.g., Wheeler, 1922b) apparently all refer to species of Pseudoneoponera, which we consider a distinct genus. True Bothroponera presumably lack these unusual secretions, though data are lacking either way.

Worker Morphology
These characters are collated in the Worker Morphology table.

Species Uncertain

 * Bothroponera sp.1:
 * Bothroponera sp.2:

Nomenclature

 * '' BOTHROPONERA [Ponerinae: Ponerini]
 * Bothroponera Mayr, 1862: 717. Type-species: Ponera pumicosa, by subsequent designation of Emery, 1901a: 42.
 * Bothroponera as subgenus of Ponera: Emery, 1895j: 767.
 * Bothroponera as subgenus of Pachycondyla: Emery, 1901a: 42.
 * Bothroponera revived status as genus: Wheeler, W.M. 1918c: 299 (footnote).
 * Bothroponera junior synonym of Pachycondyla: Snelling, R.R. 1981: 389; Hölldobler & Wilson, 1990: 11; Brown, in Bolton, 1994: 164.
 * Bothroponera revived from synonymy: Schmidt & Shattuck, 2014: 72.

Worker
Schmidt and Shattuck (2014) - Medium to large (TL 5.5–16 mm) slender to robust ants with the standard characters of Ponerini. Mandibles triangular, usually with a faint basal groove. Frontal lobes either moderately large (B. sulcata group) or very large and cordate (Bothroponera s.s.). Eyes of moderate size and placed anterior of head midline. Mesopleuron usually not divided by a transverse groove. Metanotal groove obsolete dorsally. Propodeum broad dorsally. Propodeal spiracles slit-shaped. Distinct pale glandular patch on posterior surface of metatibia, close to spur, present (B. sulcata group) or absent (Bothroponera s.s.). Metatibial spur formula (1s, 1p). Petiole nodiform, widening posteriorly in dorsal view, with vertical anterior and posterior faces. Girdling constriction between pre- and postsclerites of A4 apparent. Stridulitrum either present (Bothroponera s.s.) or absent (B. sulcata group) on pretergite of A4. Head and body either coarsely sculptured with abundant pilosity and moderate pubescence (most Bothroponera s.s.; Bothroponera laevissima is shiny, with only weak sculpturing and sparse pilosity) or finely punctate with scattered pilosity and dense pubescence (B. sulcata group). Color dark brown to black.

Joma and Mackay (2015) - Large ants, with maximum total length of 5 - 16 mm; head subquadrate in most species (excluding mandibles), suborbicular in some species, posterior border generally concave; mandibles narrowed or triangular-shaped in most species, shorter than head length with teeth number ranging from 6 to 9; anterior medial margin of clypeus convex, often sharply angled or straight to slightly concave with medial raised area; frontal lobes divided by well-developed frontal furrow; scape shorter, nearly reaches or extends slightly past posterior border of head; compound eyes vary from relatively small to large; sculpture smooth or slightly rough to punctate or foveolate; pronotal shoulder squared or rounded, but without lateral margin or carina in all species of Bothroponera; mesonotum and propodeum poorly separated by notopropodeal groove; mesometapleural suture well developed; propodeum rounded between faces, mesonotal basalar sclerite rounded or oval-shaped, propodeal spiracle elongate or slightly ovalelongate; petiole subquadrate, rounded antero-posteriorly, usually wide with definite dorsal face; stridulatory file present on second acrotergite of gaster; hairs scarce on body and usually short; color mostly dark brown or black.

Queen
Joma and Mackay (2015) - Head subquadrate or suborbiculate; pronotum rounded anteriorly, pronotal shoulder lacking carina or lateral margins; scutum wide anteriorly, reaches same width as pronotum, narrowed posteriorly to same width as scutellum; metanotum slightly elevated, narrowed, well separated from propodeum and scutellum; mesopleuron divided by anapleural sulcus to form ventral katepisternum and dorsal anepisternum; mesometapleural suture well defined; mesonotal basalar sclerite oval or round shaped, propodeal spiracles elongate or subrectangular in some species; petiole rounded anteriorly, vertical with slightly concave posterior face in some species; postpetiole rounded or subquadrate anteriorly; postpetiole and remainder of gaster larger than mesosoma; short to moderately long (up to 0.40 mm) erect golden hairs scattered on dorsum of pronotum, scutum, scutellum, metanotum, propodeum, petiole and postpetiole; short (up to 0.15 mm) erect golden hairs on head; surfaces mostly brown, dark brown or black.

Schmidt and Shattuck (2014) - Similar to the worker but slightly larger, winged and with ocelli (Wheeler, 1922b). Queens are absent in Bothroponera kruegeri, in which reproduction is performed by gamergate workers.

Male
Joma and Mackay (2015) - Head excluding mandibles rounded or elongated; eyes large, cover most of side of head; scape shorter and thicker than second segment of funiculus; pronotum triangular, scutum usually with notauli; scutellum elevated, triangular in dorsal view, metanotum slightly raised between scutellum and propodeum, mesopleuron divided by anapleural sulcus into ventral katepisternum and dorsal anepisternum; dorsopropodeum gradually sloping downward posteriorly to reach insertion of petiole; petiole small, apex rounded, width and height less than those of propodeum and postpetiole; postpetiole rounded or squared anteriorly; color mostly black or dark brownish.