Neoponera apicalis

A common and conspicuous species with large workers. Its yellow tipped antennae, black satiny body and a lack of erect setae on the top of the mesosoma make this ant relatively easy to identify.

Identification
From Mackay and Mackay (2010):

There are only a few species of Neoponera in which the workers lack erect hairs on the dorsum of the mesosoma (Neoponera magnifica, Neoponera bucki, Neoponera apicalis, Neoponera obscuricornis and Neoponera verenae). Of these species, three have very large eyes, which occupy more than ⅓ of the side of the head (N. apicalis, N. obscuricornis and N. verenae). Neoponera apicalis can nearly always be separated from the other two species with large eyes, as at least part of the funiculus of the worker, female and even the male is yellow (or pale brown in the male). This characteristic can be easily seen in the field. Neoponera apicalis could be confused with the closely related N. cooki, which also has a yellow-tipped funiculus, but N. cooki also has abundant erect hairs on the dorsum of the mesosoma, which are lacking in N. apicalis. The funiculi of the worker, female and male of N. verenae (and the worker of N. obscuricornis) are usually dark brown, but may be reddish brown near the apex, but are never yellow. The posterior lateral edge of the petiole of N. apicalis is broadly rounded into the posterior face, whereas it is mostly angulate in the petiole of N. verenae. This characteristic will also separate the females of the two species. The males are quite different, as the male of N. verenae is completely dark brown, (including the entire antennae) and the side of the petiole lacks the rugae found on the petiole of the male of N. apicalis. The last few segments of the funiculus of workers and females of N. fauveli from Colombia and Ecuador are often yellow and it looks similar to workers of N. apicalis. They can be instantly recognized by the moderately abundant erect hairs on the dorsum of the mesosoma of N. fauveli, which are mostly or completely lacking in N. apicalis.

Rarely N. apicalis may have hairs on the dorsum of the mesosoma and petiole, which may cause confusion with the Amazonian N. cooki. Such specimens of N. apicalis can be distinguished as the head is dull and covered with small punctures, not distinctly striate as it is in Neoponera cooki.

A specimen (NHMB) differs from the typical form in having a longer petiole (1.3 mm vs. 1.2 mm in the usual specimens), which is also shorter (1.6 mm from bottom margin, versus 1.65 in usual specimens), but is considered to be N. apicalis.

Wild (2005) discusses geographic variation in the shape of the petiole, number of erect hairs, especially on the gaster and the size of the eye.

Range
Southern Mexico to northern Argentina.

Distribution based on Regional Taxon Lists
Neotropical Region: Belize, Bolivia, Brazil, Colombia, Costa Rica, Ecuador, French Guiana, Guatemala, Guyana, Honduras, Mexico, Nicaragua, Panama, Peru, Suriname, Trinidad and Tobago, Venezuela.

Habitat
From Mackay and Mackay (2010): This species is common in primary and secondary wet tropical forests and in medium elevation rain forests (150 - 1500 m). It even occurs in coffee plantations and second growth thorn forest (Wild, 2005). Wild (2005) lists the elevations from sea level to 1600 meters with a mean of 642 meters. This species has been collected in caves near the entrances (Reddell and Cokendolpher, 2001). This is one of the most common species in the tropical forest in the state of Veracruz, México, but is not found in the adjacent grassland (Quiroz-Robledo and Valenzuela-González, 1995).

Abundance
Very common.

Biology
From Mackay and Mackay (2010):

"Neoponera apicalis nests in rotten wood (Levings and Franks, 1982; Dietemann and Peeters, 2000; Baena, 1993; Longino, website), including logs and stumps, or in the soil (Levings and Franks, 1982). A nest was found in root mass of a large Ficus within one meter of the ground (Fresneau, 1985). Another nest was found in bamboo (Guadua sp.) (Wild, 2005). Nests have about 30 (Mann, 1916) to 90 workers (Fresneau, 1985). Males and females were present in nests in January (Costa Rica) and May (Panamá). Dealate females have been captured in March (Costa Rica), June (Panamá), July (Costa Rica) and August (Ecuador, Venezuela). Winged males were collected in January to July (Ecuador, tree fogging) and November (Perú).

Workers are individual foragers and apparently not optimal foragers (Goss et al., 1989), but show a high degree of regional specialization that persists for extended periods of time (Fresneau, 1985). There is no recruitment and Tandem running only occurs during nest translocation (Fresneau, 1985). They are very active predators and are often captured on the ground or in pitfall traps. These ants are opportunist predators on termites in the genera Constrictotermes and Nasutitermes (Mill, 1982); and an important predator on Nasutitermes costalis (Traniello, 1981). Foragers were attracted to tuna bait and were found feeding on a dead Iguana iguana, the large green tropical lizard. Workers carry droplets of food in their mandibles, which they share with the other members of the nest, including the larvae (Dejean and Corbara, 1990). When they feed smaller larvae they hold the droplet and the larva at the same time and deposit the droplet on the body of the larger larvae.

Foragers disperse the seeds of Calathea ovandensis (Marantaceae) approximately 9 meters from where they were collected (Horvitz and Schemske, 1986a, 1986b). Foragers collect diaspores on the forest floor (Pizo and Oliveira, 2000).

Colony odor is apparently produced in the postpharyngeal gland and transferred to the epicuticle by allogrooming and not by trophallaxis (Soroker et al., 1998, 2003). Lachaud and Fresneau (1987) discuss the social regulation following an experimental sociotomy of a colony. Workers develop a dominance order with a single dominant worker, which lays eggs and maintains her position by physical attack on others and the destruction of eggs laid by subordinates (Oliveira and Hölldobler, 1990). They respond and attempt to escape from the collector and have a painful sting. Dietemann & Peeters (2000) described how workers shift from trophic to reproductive eggs following queen removal. The venom has a bitter taste due to the presence of cyclic dipeptides of leucine and phenylalanines (López and Morgan, 1997). The function of the venom may thus be both defensive and offensive. The mandibular glands contain δ-decalactone and benzalde-hyde (López and Morgan, 1997).

Caetano (1988) described the digestive and excretory system of the worker. Hölldobler and Engel-Siegel (1982) described the tergal and sternal glands of the male.

Neoponera apicalis is mimicked by the spider Castianeira memnonia  (Reiskind, 1977; Wild, 2005)."

From Longino, Ants of Costa Rica:

"In both wet and dry forested lowlands of Costa Rica, this is one of the most common and conspicuous ants. Foraging workers are extremely fast and run over the surface of trails in a nervous, erratic manner, with the antennae rapidly vibrating. Their behavior is reminiscent of pompilid wasps. Foragers are solitary hunters on the ground, where they capture live prey and scavenge on dead insects. They are never arboreal. I have only seen diurnal foragers; I do not think they forage at night. The nests are in dead wood on the ground.

Colonies are apparently monogynous, with a single queen responsible for most reproduction, but there is also a dominance hierarchy among workers (Oliveira and Hoelldobler 1990). Dominant workers are aggressive toward subordinates, have more developed ovaries, lay trophic eggs, and attend the egg pile more.

Fresneau (1985) investigated foraging in field colonies of apicalis. Workers foraged individually, and no recruitment was ever observed. Foragers had a high degree of regional specialization over time, and seemed to use visual ques for orientation. Tandem running was observed during a nest emigration, but never during foraging. Goss et al. (1989) studied foraging behavior of three colonies and developed a general model of foraging in social insects. Fresneau and Dupuy (1988) studied division of labor, and found that workers exhibit a temporal polyethism common among ants, in which workers begin in brood care, graduate to nest maintenance activities, and lastly become foragers. Fresneau and Dupuy also observed new alate queens participating in tasks similar to workers, a trait they considered primitive relative to other ants.

Soroker et al. (1998) examined colony odor formation, using radioactive tracers to tag lipid precursors. Lipids in the cuticle and the postpharyngeal gland were transferred among workers largely by allogrooming, and not by trophallaxis. Pavan et al. (1997) and Giovannotti (1996) have studied sound production in apicalis and the ultrastructure of the stridulatory apparatus. Schmidt et al. (1980) investigated venom toxicity, and Cruz and Morgan (1997) have examined venom chemistry.

During field work in Corcovado National Park in 1980, I had the opportunity to watch a colony over a period of several months. The nest was inside a 1m diameter fallen tree trunk, which was suspended 1m off the ground by its branches. The nest entrance was on the underside. I found this nest by following a returning forager. While doing a mark-recapture study on Heliconius butterflies, I spent several hours at a time at this site. While waiting for butterflies, I would often capture tabanids, lightly crush them, and feed them to ants. One day I decided to follow an apicalis worker that picked one up. It took a torturous route, up and down, backwards and forwards, taking many dead end routes from which it would return and take another. After some time, it reached the nest entrance, 10-12m from where it started. Within a minute of the time it entered the nest, a second worker arrived at the entrance with another one of my crushed tabanids. These observations are consistent with Fresneau's view that apicalis uses visual cues, such as canopy pattern, for orientation.

Another observation at the same site revealed an interesting feature of apicalis foraging behavior. One morning I set out a handkerchief on which I accumulated a dozen or so crushed tabanids. An apicalisworker found them first, and spent a long time just going from fly to fly biting off the wings. After a while Solenopsis geminata and Crematogaster erecta began to arrive. Two apicalis workers were on the handkerchief by this time, and they began to carry flies off. An apicalisworker dashed in and grabbed one last fly from the Solenopsis', but from then on it was Solenopsis and Crematogaster'' territory. The lengthy processing of multiple prey items was definitely not beneficial in this context. Maybe the apicalis worker bit off the wings of a dozen flies before doing anything else because that is step one in the program upon seeing dead insects, and seeing more than one dead insect in any one place is not a common event.

At La Selva, I have observed three nests. One was a colony foundress with a single worker in a chamber in a rotten log on the ground.

The next nest was in a soft rotten stem in the leaf litter. The stem was horizontal, half buried in litter, and half projecting over the trail. The stem was evenly cylindrical, approximately 5cm outer diameter, 3cm inner diameter. The outer, projecting portion of the stem contained soil and nest refuse. A Strumigenys colony was present in this refuse. Continuing basally was the main refuse pile. This was swarming with small white collembola, and numerous shelled gastropods. Basal to the refuse pile was the brood pile, with numerous cocooned pupae, and larvae of all sizes. There were about 100 adult workers, and about 20 adult males. I saw no queen. Approximately a quarter to a third of workers had mites clinging to the pygidium, clustered around the sting. These were visible in the field as small orange tufts at the tip of the abdomen. Later examination in lab revealed that the mites, up to 6 at a time, clung to individual setae on the pygidium. Also, I occasionally found a single mite on the inferior metatibial spine. I found a few mites clinging to tubercles on the larvae. The refuse was composed of abundant chitinous fragments (elytra, pronota, etc.) embedded in brown organic matter. Prionopelta workers were observed in cavities in the walls of the dead stick, beneath the refuse pile. I preserved most of the colony, but left a plastic bag in the lab with four workers and several pieces of the nest, including part of the refuse pile. Several days later I reexamined the contents. The refuse pile was swarming with collembola and immatures of the phoretic mites. The four workers that had remained in the bag were encrusted with adult mites, the mites clinging to setae on the tibiae and tarsi, up to 30 per leg. There was one larger mite, not the same as the phoretic mites, which I found in the refuse pile and preserved in alcohol.

A third nest was just three workers in a small chamber in a small dead trunk. The workers had the same type of mites as before, clinging to the tip of the abdomen."

Association with Other Organisms

 * Myrmecophile: Oplitis apicalis

Chemistry
Cuticular Hydrocarbons (HC) have been studied (Soroker et al. 2003) and it has been shown that individual HC profiles, influenced by injection with a radioactive precursor, were transferable to nestmates that did not directly receive injections themselves. HC profiles for all members of small groups of 11 workers were found to be uniform within 5 - 10 days of treating some individuals within the group. This is significant as Neoponera apicalis do not perform trophallaxis and only allogroom at low frequency, behaviors that are deemed to be efficient means of transferring chemical constituents among nestmates. Despite what would appear a poor system for homogenization of HC and the overall colony odor, nestmate contacts and a high concentration of newly synthesized HCs on the basitarsal brushes were suggested as the means of facilitating HC transfer.

The cuticular hydrocarbon 13-methylpentacosane (13-MeC25) differentiates queens and workers according to their level of ovarian activity (Yagound et al. 2015). Such a fertility signal underlies the regulation of reproduction in colonies.

Nomenclature

 *  apicalis. Formica apicalis Latreille, 1802c: 204, pl. 7, fig. 42 (w.) SOUTH AMERICA. Forel, 1899c: 11 (q.); Wheeler, G.C. & Wheeler, J. 1952c: 615 (l.); Mackay & Mackay, 2010: 205 (m.). Combination in Pachycondyla: Mayr, 1863: 439; in Neoponera: Emery, 1901a: 47; in Pachycondyla: Brown, in Bolton, 1995b: 302; in Neoponera: Schmidt & Shattuck, 2014: 151. Senior synonym of latreillei: Brown, 1957e: 230; of latocciput: Wild, 2005: 5. See also: Mackay & Mackay, 2010: 204.
 * latreillei. Neoponera latreillei Forel, 1905b: 161 (w.q.) SURINAM. Wheeler, G.C. & Wheeler, J. 1952c: 613 (l.). Subspecies of obscuricornis: Emery, 1911d: 72. Junior synonym of apicalis: Brown, 1957e: 230.
 * latocciput. Neoponera obscuricornis r. latocciput Forel, 1921b: 132 (w.q.) ECUADOR. Combination in Pachycondyla: Brown, in Bolton, 1995b: 306. Junior synonym of apicalis: Wild, 2005: 5.

Worker
Mackay and Mackay (2010): This species is easily recognized, even in the field, as being a common moderately large (total length ~ 12 mm) black ant with a yellow-tipped funiculus. The eyes are large with a diameter greater than the distance to the insertion of the mandible and occupy about ⅓ of the length of the side of the head (side view). A well-defined malar carina is present between the anterior edge of the eye and the clypeus. The mesosoma is weakly depressed at the metanotal suture; the petiole is thick and cuboidal-shaped when viewed in profile. The stridulatory file is present on the dorsum of the gaster, but is poorly defined. The metasternal process consists of two widely spaced triangular lobes, with horizontal striae on the inner posterior surface. Specimens from Colombia often have metasternal lobes similar to those of Neoponera verenae with the striae on the posterior face being more oblique and the inner distal half of the process being concave.

Erect hairs are sparse and mostly restricted to the head and the gaster; a few suberect hairs are present on the flexor surface of the distal half of the tibiae. The mandibles are moderately shining, with fine striate, the remainder of the ant is densely, but finely punctate with all surfaces dull.

This common attractive ant is mostly black, except for the yellow distal half of the funiculus.

Female
Mackay and Mackay (2010): The female is a large (total length 13 mm) dull black ant with approximately the last five funicular segments yellow. The remainder of the ant is similar to that of the workers, except three ocelli are well developed and the mesosoma is adapted for flight.

Male
Mackay and Mackay (2010): The male (undescribed) is a dark ferrugineous brown ant of moderate size (total length 10 mm) with the entire funiculus being pale brown (flesh-colored). The length of the head is 1.5 mm, the width (posterior to the eye) is 1.2 mm, the scape is short (0.35 mm) and the eye is large (0.95 mm). The shape of the petiole is similar to that of the worker, but differs in having the side of the petiole covered with irregular rugae.

Erect hairs are sparse with a few present on the clypeus, dorsum of the head, medial part of pronotum, dorsum of the mesosoma and ventral surface (a few hairs are present on the posterior dorsal surface) of the gaster.

Most surfaces of the male are dull and finely punctured with poorly defined striae. The sculpture of the side of the petiole is characteristic of this species, covered with coarse wrinkle-like rugae.

Etymology
The name of this species comes from Latin, apicalis meaning “pertaining to the apex”, a reference to the yellow color on the tip of the antenna. (Mackay and Mackay 2010)