Pachycondyla harpax

A common species with a wide range, it can be found in North, Central, and South America.

Identification
Mackay and Mackay (2010): Pachycondyla harpax is the most common species in the New World and is also widely distributed. The worker can be separated from most other species in the genus as it lacks the malar carina and the eye is small but is located less than one maximum diameter from the anterior edge of the head (side view). The pronotal carina is poorly developed but forms a shiny raised line (usually), the metanotal suture is absent on the dorsum of the mesosoma and the petiole is rectangular shaped with a distinct dorsal face and the posterior lateral margin forms a sharp carina, which is barely evident as it passes to the anterior edge of the petiole. The anterior face of the postpetiole forms a right angle with the dorsal face, which may be slightly concave.

The sharply angulate anterior face of the postpetiole of P. harpax could cause confusion with Neoponera procidua, but they can be easily separated as the metanotal suture of P. procidua breaks the sculpture and the petiole of P. procidua has a vertical anterior face and broadly rounded posterior face, which meet near the anterior edge of the apex of the petiole in a sharp angle. The basically rectangular-shaped petiole of P. harpax could cause confusion with Pachycondyla crassinoda, Pachycondyla striata,  and Pachycondyla impressa. Pachycondyla harpax can be easily separated from all three of these species by its much smaller size (the workers of the other three species are usually at least 10 mm in total length). Pachycondyla harpax can be separated from smaller specimens of P. impressa, as the pronotal carina is present, at least as a shiny raised line, not nearly rounded as in P. impressa. It lacks the clypeal carina found in Pachycondyla lenis of Brasil and although the pronotal carina is poorly developed, it is still obvious (nearly always) at least as a shiny raised line against the dull sculpture, not completely absent as in P. lenis.

John Longino refers to specimens which lack the pronotal carina as JTL-003. All specimens from the southern Pacific lowlands (Osa Peninsula) lack the carina, everywhere else in Costa Rica they have it (Longino, pers. comm.). They are not sympatric with the “normal” P. harpax and may represent a separate species. Longino also has a collection of this phenotype from the state of Barinas, Venezuela. We will recognize them as only a minor geographic variant in this revision.

Distribution
Southern United States through South America, Trinidad, Grenada, Jamaica. (Mackay and Mackay 2010)

Distribution based on Regional Taxon Lists
Nearctic Region: United States. Neotropical Region: Bolivia, Brazil, Colombia, Costa Rica, Ecuador, French Guiana, Greater Antilles, Grenada, Guadeloupe, Guatemala, Guyana, Honduras, Mexico, Nicaragua, Panama, Paraguay, Peru, Suriname, Trinidad and Tobago, Venezuela.

Habitat
These ants are found in a wide variety of habitats, ranging from dry forest, late dry season gap forest, urban environments, parks, grassy areas, coffee, cacao and banana plantations, cypress swamps, to oak forests, oak riparian forests, rocky wet quebradas [streams], arid scrub, palm thorn forests, tropical deciduous forests, tropical evergreen forests, second growth tropical forests, transitional bamboo/cloud forest, old growth dry tropical forest, steep rocky forest slopes, ridge forest, wet mountain forests, riparian rain forest, montane evergreen forest, lowland forests, cloud forest and riparian tropical rain forests. This species has been collected in caves near the entrances (Reddell and Cokendolpher, 2001). They occur from sea level to 2000 meters. (Mackay and Mackay 2010)

Biology
Mackay and Mackay (2010): Nests are found in the soil often under stones (Buckley, 1866) or pieces of wood, or in rotten logs, in organic matter on top of rotten logs and under cow dung (Pergande, 1895). Logs may be very large (1+ meter diameter, 2+ meters long); stones may be very heavy (200+ kg). Soils vary from clays to sandy gravel. A nest gyne was found at a soil depth of 50 cms. One nest was found in the abandoned nest of the native fire ant Solenopsis geminata. They can nest in a wide variety of soils ranging from clay to sand. Workers are commonly collected in Winkler extractions and in pitfall traps. Brood was found in nests in July (Guatemala), August (USA) and November (Colombia). Sexuals were found in nests in February (Bolivia), March to June (Texas, Mexico, Ecuador), April (México) and November (Colombia). Alate females have been collected in February (Perú) and April (Texas, Costa Rica). Dealate females have been collected in May (Mexico), June (Mexico, Costa Rica, Colombia), July to September (Mexico, Colombia), August (USA, Ecuador), October (USA, Venezuela, Bolivia) and December (México, Colombia). Loose males have been collected in January (México), February (Ecuador), April (USA), July (México, El Salvador), between January and July (Ecuador, canopy fogging), August (México), October (Panamá) and November (México) and December (México, Costa Rica). The nests have multiple ergatomorphic females (Wheeler, 1900).

Workers are predaceous (Maes, 1989) and forage primarily on the ground. They can be collected in surface traps baited with mealworms or tuna and pitfall traps. A few workers have been collected in baits hanging in the vegetation, especially trees. This species preys on worker termites (Gnathamitermes tubiformans) in northern México (Garcia-Pérez et al., 1977). Workers are alert and fast and normally not very aggressive when the nest is disturbed. Wheeler (1900) describes interesting worker behavior: they fold their antennae and “peep out” of holes and crevices in the soil “like a rat”. Workers produce foam from the tip of the gaster (Maschwitz et al., 1981; Overal, 1987), similar to workers of Pachycondyla striata.

These ants are found in the same areas as Neoponera apicalis and one nest was in the refuse of an Atta mexicana nest. Baena (1993) reported that P. harpax nests together with ants of the genus Leptogenys. Hung and Vinson (1975) describe the male reproductive system.

This species was studied in Texas by Wheeler (1900b), who found colonies under stones or logs on moderately dry hillsides, often in the shade of trees or bushes. This species "has the peculiar habit of folding its antennae and of peeping out of holes and crevices like a rat." Both winged and ergatoid queens occur. In two nests there were several dealate queens and winged queens that lost their wings "at a slight touch." This suggests that at least some winged queens have no dispersal flights. When colonies are combined, there is a period of non-lethal combat that lasts for several hours to several days, followed by the merging of the colonies. Wheeler (1900b) also includes an illustration of the larva.

Mitchell and Pierce (1912) provide notes on P. harpax in Victoria County, in southeastern Texas. They found colonies only in moist sites, such as river bottoms and lake shores. Nests were under logs, in decayed logs, or in the decomposed phloem between the outer bark and the wood. Colonies were small, with a maximum of about 150 workers. Workers were found foraging under cow dung.

Foraging
Workers employee tandem running to recruit to and forage from larger food items. Gruter et al (2018) - Studying wild colonies in Brazil, we for the first time describe tandem running in the ponerine ant Pachycondyla harpax. We asked if foragers perform tandem runs to carbohydrate- (honey) and protein-rich (cheese) food items. Furthermore, we tested whether the speed and success rate of tandem runs depend on the foraging distance. Foragers performed tandem runs to both carbohydrate food sources and protein-rich food items that exceed a certain size. The probability to perform a tandem run and the travelling speed increase with increasing foraging distances, which could help colonies monopolize more distant food sources in a competitive environment. Guiding a recruit to a food source is costly for leaders as ants are similar to 66% faster when travelling alone. If tandem runs break up (similar to 23% of all tandem runs), followers do not usually discover the food source on their own but return to the nest. Our results show that tandem running to food sources is common in P. harpax, but that foragers modify their behaviour according to the type of food and its distance from the nest. Competition with other ants was intense and we discuss how tandem running in P. harpax might help colonies to build-up a critical number of ants at large food items that can then defend the food source against competitors.

Brazil
DaRocha et al. (2015) studied the diversity of ants found in bromeliads of a single large tree of Erythrina, a common cocoa shade tree, at an agricultural research center in Ilhéus, Brazil. Forty-seven species of ants were found in 36 of 52 the bromeliads examined. Bromeliads with suspended soil and those that were larger had higher ant diversity. Pachycondyla harpax was found in 2 different bromeliads and was associated with the suspended soil and litter of the plants.

Associations with other Organisms
Foragers disperse the seeds of Calathea ovandensis (Marantaceae) approximately 75 cm from where they are collected (Horvitz and Schemske, 1986b).

This species is parasitized by the phorid fly Metopina pachycondylae (see Wheeler and Wheeler, 1952 for a survey of the literature) as well as Apocephalus sp.

Nomenclature

 *  harpax. Formica harpax Fabricius, 1804: 401 (w.) SOUTH AMERICA. Wheeler, W.M. 1900b: 4, 17 (q.m.l.); Wheeler, G.C. & Wheeler, J. 1952c: 618 (l.). Combination in Pachycondyla: Roger, 1863b: 18. Senior synonym of concinna, dibullana, irina, montezumia (and its junior synonyms amplinoda, orizabana): Brown, 1950e: 247. See also: Mackay & Mackay, 2010: 374.
 * montezumia. Pachycondyla montezumia Smith, F. 1858b: 108 (q.m.) MEXICO. Forel, 1899c: 12 (w.); Wheeler, G.C. & Wheeler, J. 1952c: 618 (l.). Junior synonym of harpax: Roger, 1862c: 288; Roger, 1863b: 18; Dalla Torre, 1893: 34. Revived from synonym as subspecies of harpax: Forel, 1899c: 12; Emery, 1911d: 75. Senior synonym of amplinoda, orizabana: Emery, 1911d: 75. Junior synonym of harpax: Brown, 1950e: 247.
 * amplinoda. Ponera amplinoda Buckley, 1866: 171 (w.) U.S.A. Junior synonym of harpax: Emery, 1895c: 266; of villosa: Forel, 1899c: 14; of montezumia: Emery, 1911d: 75.
 * dibullana. Pachycondyla harpax var. dibullana Forel, 1901f: 347 (w.) COLOMBIA. Forel, 1912c: 39 (q.). Junior synonym of harpax: Brown, 1950e: 247.
 * concinna. Pachycondyla harpax var. concinna Wheeler, W.M. 1925a: 5 (w.q.) BRAZIL. Junior synonym of harpax: Brown, 1950e: 247.
 * irina. Pachycondyla harpax var. irina Wheeler, W.M. 1925a: 5 (w.) GUATEMALA. Junior synonym of harpax: Brown, 1950e: 247.
 * orizabana. Pachycondyla orizabana Norton, 1868c: 8 (w.) MEXICO. [P. orizabana Norton, 1868a: 64. Nomen nudum.] Junior synonym of harpax: Emery, 1892b: 167; of montezumia: Emery, 1911d: 75.

Type Material
Lectotype worker, 3 paralectotype workers, 3 paralectotype females here designated, ; 3 syntypes seen, ; two syntype workers seen,, 3 syntypes workers, , 6 worker syntypes , 5 worker cotypes, 1 female cotype (Mackay and Mackay 2010)

Pachycondyla montezumia

One syntype queen in (syntype male not found). Labelled “Mex. 56/143.” Acc. Reg.: “1856 no. 143. Mexico. Purchased of Cuming. Collected by M. Sallé on and around the volcano of Orizaba, two or three are from St Thomas in the West Indies.”

Worker
Mackay and Mackay (2010): The workers are moderately large (total length up to 10 mm) black ants with dark brown appendages. The mandibles have 9 or 10 teeth; the anterior border of the clypeus is usually convex, although it may be nearly straight or even slightly concave medially. The central region of the clypeus is swollen and may even form a longitudinal carina posteriorly. The region anterior to the eye is without a malar carina, although it may be slightly raised. The eyes are relatively large (0.34 mm maximum diameter) and are separated from the insertion of the mandibles by less than one maximum diameter (side view). The scape extends only slightly past the posterior lateral corner of the head. The pronotal shoulder is nearly always formed into a definite carina, which passes forward on the anterior lateral surface of the pronotum. The metanotal suture is absent on the dorsum of the mesosoma or is only slightly developed. The petiole is rectangular-shaped with the anterior and posterior faces being nearly parallel, the posterior surface forming definite bend with the dorsal surface. Posteriorly the petiole has sharp lateral borders which define the posterior face. The anterior face of the post-petiole may be slightly concave.

Erect hairs are abundant on most surfaces, including the mandibles, clypeus, scapes, dorsum of the head, region near the eyes, ventral surface of the head, dorsum of the mesosoma, petiole and all surfaces of the gaster, the hairs on the tibiae are mostly suberect. Appressed golden pubescence is abundant on most surfaces.

The mandibles are smooth and glossy with scattered punctures, most of the dorsum of the head is covered with dense punctures, as is the mesosoma and petiole, the punctures on the dorsum of the gaster are more scattered and much of the gaster is smooth and glossy.

Queen
Mackay and Mackay (2010): The female is slightly larger (total length over 10 mm) and is similar to the worker except the mesosoma is more massive and some structures, especially the side of the pronotum, mesopleuron and the side of the propodeum, are striate. The metanotal suture is well developed, forming a definite metanotum. The wing has the typical venation of members of the genus.

Erect hairs are abundant on essentially all of the surfaces, including the mandibles, dorsal and ventral surfaces of the head, sides of the head, clypeus, scapes (often longer than the diameter of the scape), mesosoma, petiole and gaster. Fine golden appressed pubescence is present on all surfaces except the mandibles and is especially obvious on the head and gaster.

The mandibles are finely sculptured and mostly smooth and glossy, the head and mesosoma are densely punctured and weakly shining, the gaster is finely punctured and moderately smooth and glossy.

Male
Mackay and Mackay (2010): The male is also a moderate sized specimen (total length about 9 mm) black with brown legs. The eye is large, covering more than half of the side of the head. The pronotal carina, which is well developed in both the worker and female, is lacking. The metanotal suture is well developed, as is the metanotum. The petiole is somewhat rectangular shaped but is definitely narrowed toward the apex, with a rounded node (not developed into a definite dorsal surface). The posterior face of the petiole is not defined by a carina. There is considerable variability in the shape of the subpetiolar process.

Erect hairs are abundant and scattered on most surfaces; the hairs on the tibiae are mostly suberect.

Most surfaces are coriaceous and at least weakly shining, although most of the surface is hidden by appressed golden pubescence.

Etymology
The name of this species may be based on the Latin word harpe, meaning sword and possibly referring to the sting. (Mackay and Mackay 2010)