Megalomyrmex foreli

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Megalomyrmex foreli
Scientific classification
Kingdom: Animalia
Phylum: Arthropoda
Class: Insecta
Order: Hymenoptera
Family: Formicidae
Subfamily: Myrmicinae
Tribe: Solenopsidini
Genus: Megalomyrmex
Species group: leoninus
Species: M. foreli
Binomial name
Megalomyrmex foreli
Emery, 1890

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Megalomyrmex foreli casent0902330 d 1 high.jpg

Specimen Labels

Synonyms

Boudinot et al. (2013) - Megalomyrmex foreli can be baited with tuna (Brandão 2003) and Keebler Pecan Sandies and has been observed collecting small worms, consuming large insects, and tending Margarodidae in the field (Longino 2010). Colonies can be large (> 500 individuals), nesting in diffuse soil at the base of trees with an inconspicuous nest entrance (RMMA pers. obs.) or small (~100 individuals) nesting in the stems of Calathea spp. (Marantaceae) approximately 1 m above ground (Jones et al. 1991). Pyrroline and pyrrolidine alkaloids have been detected in the venom of M. foreli and are dispensed through the large flattened and weakly spatulate sting (Jones et al. 1991) possibly through oblique gaster-tip dragging.

At a Glance • Ergatoid queen  

 

Identification

Boudinot et al. (2013) - Worker uniquely identified among Central American Megalomyrmex species by (1) mandible with 5 robust, equally-spaced, subequal teeth; (2) anterior margin of clypeus recessed beneath bulging median portion. Identification supported by the following characters: (1) mesosternum with pair of pointed triangular processes; (2) metasternum with strong triangular process; (3) propodeal corners often produced as setose tubercles; (4) postpetiole often with long, thin pencil-like process. Queen Similarly identifiable as worker, but with much larger gaster, ergatoid. Male Differs from all other Central American Megalomyrmex males by the following combination: (1) very large (ML > 2.0 mm); (2) head longer than broad (CI ~98); (3) ventral margin of valviceps crescent-shaped, with anterobasal angle almost abutting base of valvura. Note that (1) and (2) are sufficient to identify M. foreli males.

Keys including this Species

Distribution

Costa Rica south to Andean regions of Colombia, Ecuador, and northern Peru; 450–1200 m elevation.

Distribution based on Regional Taxon Lists

Neotropical Region: Colombia, Costa Rica (type locality), Ecuador, Panama.


Distribution based on AntMaps

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Distribution based on AntWeb specimens

Check data from AntWeb

Biology

Jones et al. (1999) studied the venom alkaloids of M. foreli (=M. latreillei) workers collected in Garza Cocha-Añyagu, 175 km eastern of Coca, Provincia de Sucumbios Ecuador in August 12,1994.

Longino (2010) - This species occurs in moist to wet forest habitats, in mature and second growth forest. It typically occurs in mountainous regions; in Costa Rica collections are from 100–1200 m elevation. Workers are large, conspicuous ants that may be found foraging on the ground or on low vegetation. They are attracted to extrafloral nectaries and will tend Hemiptera for honeydew.

In Central America, M. foreli is known from Costa Rica, where it is not common. I have collected foreli in the central cordilleras and on the Osa Peninsula. Workers can be found on the ground and low vegetation as diurnal or nocturnal foragers. Males come to lights. On the Osa, I encountered them in the hilly interior areas, and not in coastal areas. Workers can accumulate on sources of extrafloral nectar; I once observed 15 workers together on one Costus inflorescence.

I observed a colony at the El Ceibo site on the Barva Transect in Braulio Carrillo National Park. It was in the understory of mature wet forest at night. I saw active workers on a large liana stem and discovered that there were cavities in the stem. I saw two entrance holes in the liana, with workers visible inside, and another entrance hole in the ground at the side of the liana. The workers were aggressive, readily attacking my fingers when disturbed. One of the upper entrance holes was concealed by a small aroid with basket roots. There was carton construction around the aroid roots, possibly made by the Megalomyrmex. The aroid also covered two large Margarodidae being tended by workers. Penny Gullan identified them as immature females of the subfamily Monophlebinae, probably tribe Llaveiini.

Specimens from Colombia bear labels "Cacao - associated with membracids Horiola picta (Coquebert)," and "arboles de cacao" (reported in Brandão 1990). Jones et al. (1999) studied the venom alkaloids of M. foreli (= M. latreillei) workers collected in Ecuador.

Castes

Ergatoid queen (bottom right corner) and workers in M. foreli, showing the large difference in abdomen size. Photo by Christian Peeters.

Worker

Male

Nomenclature

The following information is derived from Barry Bolton's New General Catalogue, a catalogue of the world's ants.

  • foreli. Megalomyrmex foreli Emery, 1890b: 46, pl. 5, fig. 3 (w.) COSTA RICA. [Also described as new by Emery, 1894k: 53.] Forel, 1899c: 58 (m.). Senior synonym of latreillei: Brandão, 2003: 152. See also: Brandão, 1990: 434.
  • latreillei. Megalomyrmex latreillei Emery, 1890b: 47 (footnote), pl. 5, fig. 4 (w.) (diagnosis in key) PERU. Brandão, 1990: 436 (m.). Junior synonym of foreli: Brandão, 2003: 152.

Unless otherwise noted the text for the remainder of this section is reported from the publication that includes the original description.

Boudinot et al. (2013) - We consider Megalomyrmex foreli to be a geographically variable species, following Brandão (1990, 2003) and Longino (2010). Variation observed in Central America—predominantly from Costa Rican material—reveals a mosaic of forms which vary in propodeum shape, subpostpetiolar process development, and form of the basipetiolar carina. This latter character varies from sinuate and paired, to arcing and complete. A parallel geographic mosaic of forms is observed in the species of the strictly ergatoid-queen producing Aphaenogaster phalangium complex (Longino & Cover 2004). To our knowledge, ergatoid queens of M. foreli have only been collected in Costa Rica (Peeters 2012) but are assumed to be the only reproductive strategy of the species (Brandão 1990). Importantly, none of the geographic variants of Central American M. foreli have been collected in sympatry. The queen description is based on specimens from Heredia province, Costa Rica.

Among Central American leoninus- and modestus-group species only Megalomyrmex foreli and Megalomyrmex milenae have glabrous compound eyes. This state was observed for M. foreli for all castes. In Costa Rican worker specimens (RMMA110323-01), the sting apparatus lancets were observed to be slightly longer than the sting shaft, broad, with dorsal and ventral margins approximately parallel until weakly spatulate apex. The sting shaft was as long as the lancets and much thinner, coming to a finely rounded point apically.

Description

Worker

Brandão (1990) - Mandibles smooth; anterior clypeal border round, without denticle; frontal suture not impressed; 3-segmented antennal club; 18-20 ocular facets at compound eye largest diameter; occipital margin not raised: promesonotal suture impressed dorsally: well developed paired acrotergites at mesosternum and metasternum; dorsal face and declivity of propodeum meeting in a square angle, in side view; declivity smooth but deeply excavated, forming two lateral low tubercles: epipetiolar carina not complete: nonpedunculate petiole with anteroventral denticle leading to a longitudinal translucid flange; dorsal margin of petiolar node, in side view, concave; postpetiole with sharp ventral tooth; apex of femura round.

Color: in general head, thorax and legs shiny orange with deep-brown gaster.

Queen

Boudinot et al. (2013) - Ergatoid (n=2): HW 1.73–1.75, HL 1.87–1.89, SL 2.16–2.20, OMD 0.45–0.48, EL 0.43–0.45, ML 2.74–2.89, CI 92–93, SI 115–116, EI 25–26, OMI 100–113.

Ergatoid; similar to the worker, including palpal formula of 4,3, but differing as follows: median ocellus present; foraminal carina incomplete, with 3–4 concentric incomplete carinae; metanotum distinct; propodeal tubercles more pronounced; petiolar spiracles distinctly raised on bosses; petiolar node subquadrate, with sloping parabolic anterior face and vertical posterior face forming 90° angle with dorsal face; postpetiole wider, compressed anteroposteriorly; postpetiolar sternum very short, with strong tubercle-like anteroventrally-directed process; setation finer, denser, shorter.

Male

Boudinot et al. (2013) - (n=3): HW 1.27–1.43, HL 1.30–1.44, SL 0.57–0.64, EL 0.77–0.79, ML 2.54–2.85, CI 98–99, SI 44–45, EI 55–61.

Head Antennae with 13 antennomeres; antennomere 4 kinked near base; no other kinks and without club. Entire antenna orange-yellow. Palpal formula 3,3. Mandible triangular; masticatory margin with 5 triangular teeth; apical tooth largest, basal four teeth subequal. Dorsal face of mandible roughened and with striations. Minimum distance between lateral ocellus and compound eye slightly greater than one lateral ocellus length. Compound eye glabrous. Occipital carina visible in full-face view. Mesosoma Mesosoma attenuate. Notauli absent. Parapsidal lines distinct. Foraminal carina absent, but at least two carinae are present arcing over foramen. Metasternum with a distinct fang-like process. Basitarsi tubular. Pterostigma well-developed, somewhat narrow and elongate. Forewing crossvein 1m-cu absent; submarginal cell 1 length about four times width; terminal abscissa of M absent. Metasoma Basipetiolar carina composed of two sinuate carinae which are parallel for the posterior third of their length. Ventrolateral longitudinal carina of petiole present. Petiolar spiracle just posterad anterior third. Petiolar and postpetiolar posterior margins without girdling carinae. Postpetiolar helcium weakly elliptical in the horizontal plane. Postpetiolar spiracle placed at about midlength of lateral margin. Sternum of postpetiole with an anterior bulge which slopes gently to the posterior margin. Postpetiolar tergum weakly convex with apex distinctly in posterior half of postpetiole. Genitalia Abdominal sternum IX slightly longer than broad; lateral margins tapering to rounded apex; apex not heavily sclerotized, nor produced ventrally. Telomere triangular in profile view, with apex rounded; dorsal and ventral margins linear; without medial dentiform process; medial face of telomere sclerotized, subrectangular; ventral margin without sclerotized denticles. Cuspis with apicodorsal and apicoventral margins strongly rounded, apical margin almost without linear portion. Digitus broad; apex rounded but angular; dorsal margin angular, with a linear basal portion meeting a weakly convex distal portion at approximately 90°, this angle is rounded; ventral margin shallowly arched; ventral margin concealing apicodorsal angle of cuspis. Valviceps less than half as tall as long; dorsal margin linear, sloping posteroventrally to short, rounded apex; ventral margin convex, broadest anterad midlength; penisvalvar teeth short, truncate, and close-set.

Type Material

Boudinot et al. (2013) - Lectotype worker (designated by Brandão 1990: 434): COSTA RICA, Jimenez (near Guapiles, Prov. Limón) Museo Civico di Storia Naturale, Genoa (not examined).

References