Neoponera marginata

This is a relatively common, surface ground forager, termite feeding species (Wheeler 1936; Leal & Oliveira 1995; Hölldobler et al. 1996). The workers are usually collected through pitfall traps or by hand. Alate females and queens are much less commonly captured, unless searching for underground colonies. Males are quite rare, though they might be present in bulk Malaise samples. Due to their similarity to males of Neoponera mashpi, and likely also to males of Neoponera laevigata (which were not examined here), they can be misidentified as such. In warm morning hours the workers can be quite active around the nest entrance on the ground surface: while taking photos of them at a tourist trail, in Reserva Guartelá, southern Brazil, Adrian Troya observed ca. 10–20 workers removing soil particles from underground and piling them some 30 cm near the entrance. None of the ants showed aggressiveness when clearing part of the surrounding grass in order to get a clearer view, nor even when collecting some specimens. (Troya & Lattke, 2022)

Identification
From Mackay and Mackay (2010): The worker and female of N. marginata are easily separated from all of the other species of Pachycondyla by the longitudinal fold or carina on the dorsal surface of the mandible, which none of the other species has. Additionally the worker, female and male are mostly smooth and glossy, which is uncommon in Pachycondyla.

The specimens from Trinidad do not have the strong separation of the two surfaces of the mandibles, atypical of this species.

Distribution
TRINIDAD, BRASIL, BOLIVIA, PARAGUAY, ARGENTINA. (Mackay and Mackay 2010)

Distribution based on Regional Taxon Lists
Neotropical Region: Argentina, Brazil, Ecuador, Paraguay.

Habitat
Neoponera marginata is found in secondary lowland rainforest and urban habitats, from 30 to 700 meters elevation. (Mackay and Mackay 2010)

Biology
(Troya & Lattke, 2022): Despite being comparatively easy to identify, and commonly collected in the field, most of what is known about the behavioral biology of N. marginata is basically summarized in three studies. In the first, Leal and Oliveira (1995) provided a comprehensive account on the group-raiding and migratory habits of this species in a semi-deciduous region of the state of São Paulo in southeastern Brazil. The authors recorded more than 200 raids, all of them directed against the termite species Neocapritermes opacus (Hagen). Within the N. laevigata group this “extreme diet specialization” has been documented only in this species, so far (but see Krishna & Araujo 1968; Mill 1982b). Leal and Oliveira (1995) also concluded that N. marginata shows a rudimentary form of the “army ant syndrome”, with colonies relocating their nests less frequently than other group–raiding taxa, as for example, some Dorylinae. On the other hand, in regards to the communication system, Hölldobler et al. (1996) found that the pygidial gland of N. marginata produces Citronelal, the main monoterpenoid responsible for triggering trail-recruitment in ants. The third main contribution came from Acosta–Avalos et al. (1999) who found magnetic iron oxides in the head and gaster of N. marginata (but see also Wajnberg et al. 2017). Based on this result, they proposed that colonies of this species use the geomagnetic field during migrations, i.e., nest relocations. Two years later, Acosta-Avalos et al. (2001) linked that hypothesis to their observations of N. marginata colonies displaying a preferred directional migration which is deviated ca. 12° from the magnetic North–South axis.

Nomenclature

 * . Ponera marginata Roger, 1861a: 8 (w.q.m.) BRAZIL (Minas Gerais).
 * Type-material: 2 syntype workers, 1 syntype queen, 1 syntype male.
 * Type-locality: Brazil: St. Joao del Rey (no collector’s name).
 * Type-depositories: MNHU, ZSBS.
 * Combination in Euponera (Mesoponera): Emery, 1901a: 47;
 * combination in Termitopone: Wheeler, W.M. 1936d: 166;
 * combination in Pachycondyla: Roger, 1863b: 18; Brown, in Bolton, 1995b: 307;
 * combination in Neoponera: Schmidt, C.A. & Shattuck, 2014: 151.
 * Status as species: Roger, 1863b: 18; Mayr, 1863: 449; Emery, 1888c: 353; Emery, 1890a: 71 (in key); Dalla Torre, 1893: 34; von Jhering, 1894: 380; Forel, 1895b: 114; Emery, 1896h: 625; Forel, 1908c: 345; Forel, 1909a: 252; Emery, 1911d: 82; Forel, 1911c: 285; Bruch, 1914: 214; Santschi, 1916e: 366; Gallardo, 1918b: 67 (redescription); Luederwaldt, 1918: 35; Borgmeier, 1923: 71; Wheeler, W.M. 1925a: 6; Wheeler, W.M. 1936d: 166 (redescription); Borgmeier, 1948b: 463; Borgmeier, 1959a: 315; Kempf, 1972a: 249; Bolton, 1995b: 307; Wild, 2002: 11; Wild, 2007b: 40; Mackay & Mackay, 2010: 455 (redescription); Feitosa, 2015c: 99.
 * Distribution: Argentina, Bolivia, Brazil, Paraguay, Trinidad.

Type Material
Brasil: Minas Gerais: São João d’El-Rey (Mackay and Mackay 2010)

Worker
From Mackay and Mackay (2010): Workers are dimorphic (Wheeler, 1936). The mandible has approximately 10 teeth or denticles and is peculiar in that the surface is divided longitudinally into an external and internal area by a longitudinal fold or carina. The anterior medial margin of the clypeus is angulate, the eyes are relatively large (maximum diameter 0.4 mm) located about ½ diameter from the anterior edge of the head (side view). The malar carina is absent. The scape extends slightly past the posterior lateral corner of the head, the posterior border is straight. The pronotum is without a carina, although it is slightly swollen in that region. The metanotal suture breaks the sculpture on the dorsum of the mesosoma and the metanotum is moderately developed. The propodeal spiracle is slit shaped. The petiole is thickened when viewed in profile with the anterior and posterior faces being nearly parallel and the dorsal face being broadly rounded. The subpetiolar process consists of a swollen region, not very well differentiated from the remainder of the petiole. The stridulatory file may be absent or present on the second pretergite and the arolia are poorly developed. The metasternal process consists of two inwardly curved slender lobes. Erect hairs are scattered on the mandibles, clypeus, dorsal and ventral surfaces of the head, dorsum of the mesosoma, legs (mostly suberect), dorsum of the petiole and all surfaces of the gaster; appressed pubescence is essentially absent.

Most surfaces are smooth and glossy, a few striae are present on the mesopleuron and the side of the propodeum.

Queen
From Mackay and Mackay (2010): The female is a large (total length 13 mm) shiny black ant with reddish brown appendages. The mandibles have a large sharp apical tooth followed by a series of small denticles. The mandible is divided longitudinally as in the worker with the inner half being strongly concave. The anterior margin of the clypeus is convex, the sides of the head are narrowed anteriorly and the posterior margin is nearly straight. The malar carina is poorly developed and is represented by a depression surrounded on both sides by slightly swollen areas. The eye is moderate sized (maximum diameter 0.75 mm) and is less than one maximum diameter from the anterior edge of the head (side view). The pronotal shoulder is swollen but does not form a distinct margin; the propodeal spiracle is slit-shaped. The petiole is nearly rectangular-shaped with the anterior and posterior faces being nearly parallel, but is noticeably narrowed dorsally.

Erect hairs are present on most surfaces, including the mandibles, clypeus, dorsal and ventral surfaces of the head, dorsum of the mesosoma, dorsum of the petiole and all surfaces of the gaster. The hairs on the tibiae are mostly suberect and the length of most is approximately ½ the diameter of the tibia.

The dorsum of the head and mesosoma are smooth and glossy, the side of the pronotum and mesopleuron are both smooth and glossy, the side of the propodeum has horizontal striae, the petiole and gaster are smooth and glossy.

Male
From Mackay and Mackay (2010): The male is a moderate sized (total length 11 mm) shiny black ant with brown appendages. The mandibles are tiny. The anterior margin of the clypeus is slightly concave and the clypeus is swollen when viewed in profile. The head is narrowed anteriorly and the posterior border is broadly rounded. The eye is large (maximum diameter 0.73 mm). The median ocellus is about one diameter from the lateral ocellus (seen obliquely from above and from the side). The pronotum is broadly rounded at the shoulder; the propodeal spiracle is slit-shaped. The petiole has the general shape of that of the worker and the female, except that it is more narrowed toward the apex. The stridulatory file is present on the second pretergite.

Erect hairs are abundant on most surfaces, including the clypeus, all surfaces of the head, the scape nearly lacks erect and suberect hairs, erect hairs are present on the dorsum of the mesosoma, dorsum of the petiole and all surfaces of the gaster. The hairs on the legs are mostly suberect. Appressed pubescence is sparse, but is present on the pronotum, middle of the scutum, the scutellum and the dorsal face of the propodeum. The appressed hairs on the dorsum of gaster are sparse.

Most surfaces are moderately to strongly shining, especially the head, the mesosoma and the posterior face of the petiole. There is little sculpture, except for the side of the propodeum, which is covered with coarse rugae.

Etymology
The name of this species is from Latin, marginatus, meaning “enclosed with a border”, referring to the peculiar form of the mandible of the worker and female. (Mackay and Mackay 2010)

References based on Global Ant Biodiversity Informatics

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