Pseudoponera stigma

A predaceous ant that is commonly found in sifted leaf litter and rotten wood (Maes 1989, Mackay and Mackay 2010).

Identification
From Mackay and Mackay (2010): The worker and female of P. stigma are difficult to confuse with any of the other species of the genus Pachycondyla, based on the small number of mandibular teeth and broadly rounded subpetiolar process and the poorly developed horizontal carina on the clypeus.

Pachycondyla stigma is similar to Pachycondyla succedanea. Workers of P. stigma can be separated as they are slightly larger (total length > 4 mm, 4 mm or less in P. succedanea), the horizontal carina on the clypeus is poorly developed (well-developed and formed into a sharp carina in P. succedanea) and the subpetiolar process is broadly rounded posteriorly (angulate in P. succedanea). The females and males of P. stigma can also be distinguished from those of P. succedanea by the lack of an angle on the posterior edge of the subpetiolar process. Pachycondyla succedanea has the subpetiolar process angulate posteriorly, it is mostly restricted to Costa Rica, and the female has seven mandibular teeth.

Pachycondyla stigma can be distinguished from another closely related species, Pachycondyla cognata, as the latter species has seven mandibular teeth, the subpetiolar process is angulate posteriorly and P. cognata is mostly restricted to Costa Rica.

Pachycondyla stigma is very similar to Pachycondyla gilberti. The workers and females of both species have 6 mandibular teeth and the subpetiolar process is rounded posteriorly. They can be easily separated as the horizontal carina is well developed on the clypeus of workers and females of P. gilberti; it is nearly absent in workers and females of P. stigma. The males are difficult to separate. Those of P. gilberti tend to be smaller (total length 3.5 - 5 mm) and medium brown, those of P. stigma larger (TL 5 - 6 mm) and dark brown. Kempf (1960a) separated P. gilberti from P. stigma using a number of characteristics, especially the form of the mandibles of the female, which are not elongated as in P. stigma and are more worker-like.

The male of P. stigma is nearly identical to that of Pachycondyla arhuaca. It differs is in being slightly more hairy, specifically with erect or suberect hairs between the eye and the clypeus and on the scutum. The apex of the petiole is more angulate in P. arhuaca than it is in P. stigma. All of the above mentioned species are very similar to members of the genus Hypoponera. They can all be separated by the presence of a pair of tibial spurs on the posterior tibia; only one spur is present in members of Hypoponera. The mandibular teeth of the worker and female of Pachycondyla are well developed, not consisting of only small denticles as in workers and females of Hypoponera.

There is considerable variability in P. stigma. Wheeler and Mann (1914) referred to smaller (total length 3.5 - 4.5), red specimens from Haiti as Euponera (Trachymesopus) stigma var. rufescens. Wheeler and Mann (1914) state that the workers could not be callows, as the callows of P. stigma have a drab color. Examination of the type material (MCZC) suggests it does not differ from P. stigma significantly and it is considered a synonym. Forel (1893) recognized P. stigma var. attrita from St. Vincent Island as a separate taxon. It differs primarily in its larger size (6 - 6.2 mm). Forel lists additional characters, including the denser sculpture and duller integument, longer, narrower mandibles, with the concave external border. He states that these characters are not consistent and that intermediates were found. It is thus also considered to be a synonym of P. stigma.

Distribution
Southern United States through South America, Caribbean. (Mackay and Mackay 2010)

This taxon was described from South America.

Habitat
From (Mackay and Mackay 2010: This common species is found in a variety of habitats, ranging from grasslands (Quiroz-Robledo and Valenzuela-González,1995), disturbed rain forest in a park, wet lowland forest, at the edge of a lake, forest patch, grass with weeds and scattered trees, dry evergreen forest, primary and secondary growth rain forest, transition between tierra firme and seasonal flooded forest, in a clearing in secondary forest, a steep forest ravine slope, a wet quebrada, evergreen tropical forest, moist live oak/pine forest 10 - 15 m tall, at elevations ranging from 0 – 2300 m. One collection from México was found at 3400 m (MCZC). It is often found nesting in the shade. This species was found apparently accidentally in a cave (Reddell and Cokendolpher, 2001).

Longino (1997) states that it is common in wet lowland habitats in Costa Rica, including mangroves and is usually found in open or disturbed sites, as well as banana plantations and mature rain forest.

Biology
From Mackay and Mackay (2010): Nests are found in the soil, often under litter, or rotten logs, in rotten wood, under bark, in a well rotted Nasutitermes termite nest on the forest floor and occasionally in twigs. They nest in moist sand. They are also collected under flower litter, in forest litter, in dead stems and in rotten pine branches on forest floor. Brood was present in nests in July (Belize, Guatemala, Nicaragua, Ecuador) and August (Costa Rica). Winged females and males were collected in nests in January (Ecuador), February (Costa Rica, Venezuela, Brasil), March (Colombia, Perú, Jamaica), April, August (México), May (Panamá, Martinique), July (Guatemala, Costa Rica, Panamá, Perú), August (Panamá, Jamaica), September (Honduras), October (Perú, Venezuela, Paraguay, Guana Island) and December (México, Honduras). The sexuals are attracted to blacklights and mercury vapor lamps. Alate females were collected March (Costa Rica, Colombia), June and July (Perú), July (Costa Rica, Ecuador), July and August (México, Brasil) and October (Guano Island). Dealate females have been collected in May (Ecuador), June (México), July (Guatemala, Nicaragua), August (Costa Rica) and September (Guatemala). A colony-founding queen was found in a large rotten log in January (Costa Rica) and a female was collected under bark in June. Mating flights occur between 07:30 and 11:30.

The specimens from French Guiana were nesting in the plant Phyllodendron linnei. Specimens were collected on flowers of Eupatorium sp. [Asteraceae].

The frog Dendrobates bistrionicus eats workers of this species.

Puerto Rico
Wheeler (1908): Numerous workers from small colonies nesting under stones or logs. One colony in Culebra was found nesting in a rotten Cactus stump.

Behavior
Oliveira et al. (1998) discuss the division of labor in this species, with emphasis on the mutual antennal rubbing that occurs between nestmates. They are not rapid ants and escape when the nest is disturbed. Although they are small, they can sting.

Nomenclature

 *  stigma. Formica stigma Fabricius, 1804: 400 (q.) SOUTH AMERICA. Wheeler, G.C. & Wheeler, J. 1952c: 627 (l.); Wheeler, G.C. & Wheeler, J. 1976a: 55 (l.); Mackay & Mackay, 2010: 520 (m.). Combination in Ponera: Mayr, 1863: 450; in Pachycondyla (Pseudoponera): Emery, 1900c: 314; Emery, 1901a: 46; in Euponera (Pseudoponera): Forel, 1901g: 398; in E. (Trachymesopus): Emery, 1911d: 85; in Trachymesopus: Wilson, 1958d: 355; Kempf, 1960f: 424; in Mesoponera: Wheeler, G.C. & Wheeler, J. 1976a: 55; in Pachycondyla: Brown, in Bolton, 1995b: 310. Senior synonym of americana, quadridentata (and its junior synonym myopa): Emery, 1887b: 434; of brunneus, nixoni, quadridentata, sexdentatus: Wilson, 1958d: 355; of attrita, rufescens: Mackay & Mackay, 2010: 519.
 * quadridentata. Ponera quadridentata Smith, F. 1859a: 143 (q.) INDONESIA (Aru I.). Roger, 1860: 285 (w.); Emery, 1900c: 314 (m.). Combination in Pachycondyla (Pseudoponera): Emery, 1900c: 314; in Euponera (Trachymesopus): Emery, 1911d: 85. Subspecies of stigma: Emery, 1897d: 552; Karavaiev, 1926d: 419. Senior synonym of myopa: Roger, 1860: 285. Junior synonym of stigma: Emery, 1887b: 434; Wilson, 1958d: 355.
 * myopa. Ponera myopa Roger, 1860: 285 (w.) no locality given. Junior synonym of quadridentata: Roger, 1860: 285.
 * americana. Ponera americana Mayr, 1862: 722 (w.) COLOMBIA. Junior synonym of stigma: Emery, 1887b: 434.
 * attrita. Ponera stigma var. attrita Forel, 1893g: 362 (w.q.m.) ANTILLES. Combination in Pachycondyla (Pseudoponera): Emery, 1901a: 46; in Euponera (Trachymesopus): Emery, 1911d: 85; in Trachymesopus: Kempf, 1972a: 251; in Pachycondyla: Brown, in Bolton, 1995b: 303. Junior synonym of stigma: Mackay & Mackay, 2010: 519.
 * rufescens. Euponera (Trachymesopus) stigma var. rufescens Wheeler, W.M. & Mann, 1914: 13 (w.q.) HAITI. Combination in Trachymesopus: Kempf, 1972a: 251; in Pachycondyla: Brown, in Bolton, 1995b: 309. Junior synonym of stigma: Mackay & Mackay, 2010: 519.
 * nixoni. Euponera (Trachymesopus) nixoni Donisthorpe, 1943d: 441 (q.) NEW GUINEA. Donisthorpe, 1948b: 299 (w.). Junior synonym of stigma: Wilson, 1958d: 355.
 * brunneus. Euponera (Trachymesopus) brunneus Donisthorpe, 1948b: 300 (w.q.) NEW GUINEA. Junior synonym of stigma: Wilson, 1958d: 355.
 * sexdentatus. Euponera (Trachymesopus) sexdentatus Donisthorpe, 1949c: 746 (w.) NEW GUINEA. Junior synonym of stigma: Wilson, 1958d: 355.

Worker
From Mackay and Mackay (2010): The worker of this species is easily recognized as the mandible has only 6 teeth. Workers are small (total length 5 mm) dark reddish brown with paler brown appendages. The eyes are tiny (maximum diameter 0.07 mm) and located approximately two diameters from the anterior margin of the head (side view). The scapes extend to the posterior lateral corners of the head. The dorsum of the mesosoma is nearly flat (in profile) with the promesonotal suture weakly depressed and the metanotal suture more strongly depressed below the level of the mesosoma. The side of the propodeum is depressed near the posterior edge of the mesopleuron with the side forming a sharp edge with the posterior face of the propodeum. The petiole is narrow when viewed in profile with the anterior and posterior faces meeting at the apex in a blunt angle. The subpetiolar process is blunt and rounded both anteriorly and posteriorly. The anterior border of the postpetiole is slightly concave and is abruptly rounded into the dorsal face. Erect hairs are abundant on most surfaces, including the mandibles, the dorsal surface of the head, the scapes, the dorsum of the mesosoma, the legs, the petiole and all surfaces of the gaster. Golden appressed pubescence is found on most surfaces.

The head, mesosoma and gaster are mostly dull and covered with fine punctures, the mandibles are striate and moderately shining.

Queen
From Mackay and Mackay (2010): The female is similar to the worker, except slightly larger (about 7 mm total length) with well-developed ocelli and the mesosoma adapted for flight. The mandible has 6 well-developed teeth and the clypeus is separated into two sections horizontally by a horizontal fold. The eyes are relatively large (maximum diameter 0.36 mm) located about one third of the maximum diameter from the anterior border of the head (side view). The scapes extend slightly past the posterior lateral corner. The petiole is similar in shape to that of the worker and the subpetiolar process is rounded both anteriorly and posteriorly.

Erect hairs are present on the mandibles, clypeus, shaft of the scape, posterior margin of the head, dorsal and ventral surfaces of the head, mesosoma, petiole and gaster. The legs have few erect and suberect hairs. Most surfaces are covered with a fine dense golden pubescence, which is slightly raised from the surface.

The mandibles are smooth and glossy with fine striae and scattered punctures, the remainder of the surfaces are dull and finely punctate, the gaster is weakly shining.

Male
From Mackay and Mackay (2010): The male (undescribed) is small (total length about 5 - 6 millimeters). The mandibles are very tiny and mostly hidden when closed. The horizontal carina on the clypeus is barely developed. The eyes are intermediate in size (maximum length 0.45 mm) located about 1/5 of the maximum diameter from the anterior border of the head (side view). The scape is short (0.15 mm) and the pedicel is even shorter (0.05 mm). The ocelli are well developed. The petiole and the subpetiolar process are similar to those of the worker.

Erect and suberect hairs are present on the clypeus, sides of the heads, posterior margin, dorsal and ventral surfaces of the head, mesosoma, petiole and all surfaces of the gaster; there are few erect or suberect hairs on the legs. Fine golden appressed pubescence is presence on most surfaces, but is very sparse as compared to the female.

Most surfaces are covered with coriaceous sculpture, but many regions are at least moderately shining, especially the side of the mesosoma, petiole and gaster.

Type Material
lectotype worker, 2 paralectotype workers, 1 paralectotype female designated,, 3 syntype workers seen, (Mackay and Mackay 2010)

Type Locality Information
South America; Colombia; New Guinea; New Guinea, Donisthorpe; Antilles: Saint Vincent; Haiti, Lago Assuei near Manneville. (Mackay and Mackay 2010)

Etymology
The name of this species is based on the Greek word stigma, meaning mark or spot, possibly referring to the stigma on the wing of the female. (Mackay and Mackay 2010)

Additional References

 * Forel, A. 1893. Formicides de l’Antille St. Vincent. Récoltées par Mons. H. H. Smith. Transactions of the Entomological Society of London 1893:333-418.




 * Maes, J.M. 1989. Catálogo de los insectos controladores Biológicas en Nicaragua. Volumen I. Insectos depredadores (Primera parte). Revista Nicaraguense de Entomología 8:1-106.


 * Oliveira, P.S., M. Obermayer and B. Hölldobler. 1998. Division of labor in the Neotropical ant, Pachycondyla stigma (Ponerinae), with special reference to mutual antennal rubbing between nest-mates (Hymenoptera). Sociobiology 31:9-24.


 * Quiroz-Robledo, L. and J. Valenzuela-González. 1995. A comparison of ground ant communities in a tropical rainforest and adjacent grassland in Los Tuxtlas, Veracruz, Mexico. Southwestern Entomologist 20:203-213.


 * Reddell, J. and J. Cokendolpher. 2001 Ants (Hymenoptera: Formicidae) from the caves of Belize, Mexico and California and Texas (U.S.A) Texas Memorial Museum, Speleological Monographs 5:129-154.


 * Wetterer, J.K. 2012. Worldwide spread of the stigma ant, Pachycondyla stigma (Hymenoptera: Formicidae). Myrmecological News 16:39-44.


 * Wheeler, W. M. 1908a. The ants of Porto Rico and the Virgin Islands. Bull. Am. Mus. Nat. Hist. 24: 117-158.


 * Wheeler, W. and W. Mann. 1914. The ants of Haiti. Bulletin of the American Museum of Natural History 33:1-61.