Simopelta williamsi

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Simopelta williamsi
Scientific classification
Kingdom: Animalia
Phylum: Arthropoda
Class: Insecta
Order: Hymenoptera
Family: Formicidae
Subfamily: Ponerinae
Tribe: Ponerini
Genus: Simopelta
Species: S. williamsi
Binomial name
Simopelta williamsi
Wheeler, W.M., 1935

Workers have been collected from leaf litter.


Mackay and Mackay (2008) - This species could be confused with Simopelta breviscapa. It differs in having much longer scapes, which extend well past the posterior lateral corner of the head (the scapes extend only slightly past the corner of the head in S. breviscapa). This species is similar to Simopelta fernandezi, but can be separated by the truncated basal mandibular tooth, which is sharp in S. fernandezi. Additionally, the mesonotum is about the same length as the dorsal face of the propodeum, when they are viewed in profile. It can be separated from S. vieirai as the petiole has sculpture on all surfaces, and is not nearly smooth and glossy as in S. vieirai.

A few specimens have a relatively long mesonotum, as well as an elongated petiolar node (Colombia: Magdalena, Valle del Cauca, Caquetá, IAVH). The specimens will be considered to be “near williamsi” until more specimens become available.

Keys including this Species


Latitudinal Distribution Pattern

Latitudinal Range: 5.13333° to -2.2733°.

Tropical South

Distribution based on Regional Taxon Lists

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

Distribution based on AntMaps


Distribution based on AntWeb specimens

Check data from AntWeb


Wet cloud forest at 570 (Wheeler, 1935) - 1450 meters elevation.



Known only from the worker caste.



The following information is derived from Barry Bolton's Online Catalogue of the Ants of the World.

  • williamsi. Simopelta williamsi Wheeler, W.M. 1935d: 14, fig. 3 (w.) ECUADOR.
    • Type-material: 6 syntype workers.
    • Type-locality: Ecuador: Naranjapata, 1850 ft, xii.1922 (F.X. Williams).
    • Type-depository: MCZC.
    • Combination in Belonopelta: Baroni Urbani, 1975b: 300 (in key);
    • combination in Simopelta: Bolton, 1995b: 383.
    • Status as species: Borgmeier, 1950a: 369; Gotwald & Brown, 1967: 267; Kempf, 1972a: 230; Baroni Urbani, 1975b: 300 (in key); Brandão, 1991: 331; Bolton, 1995b: 383; Mackay & Mackay, 2008: 324 (redescription); Fernández & Guerrero, 2019: 546.
    • Distribution: Colombia, Costa Rica, Ecuador.

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



Length 3.3 mm.

Head nearly a fourth longer than broad, subrectangular, very slightly broader in front than behind, with nearly straight sides and posterior border. Eyes strongly convex, hemispherical, situated at the anterior fourth of the head. Mandibles rather broad, with evenly convex external and sharp masticatory borders, furnished with three teeth, the basal broad, truncated and separated by a toothless diastema from the two approximated and rather long apical teeth. Clypeus abrupt, perpendicular, bluntly carinate, its anterior border triangularly produced in the middle but without a spine. Frontal carinae narrow, subangular laterally; frontal groove shallow anteriorly, deep posteriorly, not reaching the middle of the head.

Antennae long; scapes som•ewhat arcuately bent, surpassing the posterior border of the head by a distance equal to their greatest diameter; first funicular joint nearly twice as long as broad, second decidedly broader than long, 3-10 longer than broad but the eighth to tenth only slightly so; terminal joint distinctly enlarged, glandiform, pointed, as long as the three preceding joints together. Thorax broad through the pronotum, which without the well-developed neck is as broad as long, with convex sides and less convex dorsum; promesonotal suture distinct and impressed; mesonotum laterally compressed, in profile straight and sloping to the distinct but shallow mesoepinotal impression; mesoepinotal suture obsolete; mesosternum with a small but distinct denticle near the insertion of the middle coxa; epinotum nearly twice as long as broad, scarcely broader behind than in front, strongly and transversely rounded above, in profile straight and horizontal, rounding posteriorly through a semicircular arc into the declivity, the lower portion of which is straight, perpendicular and submarginate on the sides. Petiole narrow, about one and one-half times as long as broad, broader behind than in front, with well-developed anterior teeth. In profile the node is higher than long and slightly higher behind than in front, with straight and perpendicular anterior and posterior surfaces, and feebly convex superior surface, the tooth depending from the ventral surface large and acutely angular. Postpetiole broader than long, not strongly truncated anteriorly and not marked off from the gaster by a constriction, so that the postpetiolar portion of the abdomen is short and oval and closely resembles that of Odontomachus. Sting well-developed. Legs slender.

Shining; the postpetiolar portion of the gaster more so than the remainder of the body; mandibles, head and thorax densely and finely reticulate or shagreened, with the following superimposed sculpture: head above and behind regularly reticulate-rugulose, anteriorly more longitudinally rugulose, on each side of the gula obliquely rugose, with several coarse punctures or foveolae; pronotum reticulately and concentrically, pleurae more strongly and sublongitudinally rugulose; mesonotum, base and declivity sharply, regularly and transversely rugulose or striate; sculpture of petiole more finely rugulose than that of the thorax, the rugules on the summit of the node being indistinctly concentric, on the sides longitudinal and on the anterior land posterior surfaces transverse. Postpetiolar portion of abdomen very smooth and shining, with sparse piligerous punctures. Antennal scapes more sharply, legs more delicately granular or shagreened.

Pilosity white, erect, of uneven length, longest and most abundant on the head, less so on the thorax, shortest on the abdomen; oblique and rather abundant on the antennae and legs. Pubescence present only on the funiculi.

Piceous or brown black; lower portions of epinotum more reddish; legs including coxae castaneous; tarsi, tip of gaster and sting yellowish.

Mackay and Mackay (2008) - The worker is a moderate sized (total length slightly more than 4 mm), dark reddish brown ant, with slightly lighter colored legs. The mandible has three well-developed teeth, the basalmost tooth (third) is nearly always obliquely truncated, the middle (second) tooth is sharp. The anterior border of clypeus is broadly rounded. The eye is small (maximum diameter 0.05 mm). The scape extends well past the posterior lateral border of the head. The length of the mesonotum is approximately equal to the length of the dorsal face of the propodeum (both seen in profile). Anterior and posterior faces of the petiole are approximately parallel, and a well-developed dorsal face is present. The node of the petiole, as seen from above, is in the shape of a square, with relatively square corners posteriorly, and rounded anteriorly. The spiracular horns of the petiole are well-developed, as is the subpetiolar process, which is angulate posteriorly.

The dorsum of the head is covered with transverse, curved striae, similar striae are present on the dorsum of the pronotum, where many of them form concentric circles, the striae on the mesonotum and dorsum of the propodeum are mostly transverse, and partially absent on the dorsum of the propodeum. The striae on the side of the petiole are very poorly formed, leaving the surface slightly smooth and glossy. The dorsum of the petiole has a few, fine, transverse striolae, with part of the surface smooth and glossy. The dorsum of the postpetiole is finely coriaceous, but mostly smooth and glossy.

Type Material

Described from six speciemns taken by Dr. F. X. Williams during December, 1922, at Naranjapata, Ecuador, at an altitude of 1850 ft.

Mackay and Mackay (2008) - Worker, Ecuador: Naranjapata; cotype seen, Museum of Comparative Zoology


References based on Global Ant Biodiversity Informatics

  • Baroni Urbani C. 1975. Contributo alla conoscenza dei generi Belonopelta Mayr e Leiopelta gen. n. (Hymenoptera: Formicidae). Mitt. Schweiz. Entomol. Ges. 48: 295-310.
  • Borgmeier T. 1950. A fêmea dichthadiiforme e os estádios evolutivos de Simopelta pergandei (Forel), e a descrição de S. bicolor, n. sp. (Hym. Formicidae). Revista de Entomologia (Rio de Janeiro) 21: 369-380.
  • Brandao, C.R.F. 1991. Adendos ao catalogo abreviado das formigas da regiao neotropical (Hymenoptera: Formicidae). Rev. Bras. Entomol. 35: 319-412.
  • Bustos H., J. 1994. Contribucion al conocimiento de al fauna de hormigas (Hymenoptera: Formicidae) del occidente del Departamento de Narino (Colombia). Bol. Mus. Ent. Univ. Valle 2(1,2):19-30
  • Fernández F. 2008. Subfamilia Ponerinae s.str. Pp. 123-218 in: Jiménez, E.; Fernández, F.; Arias, T.M.; Lozano-Zambrano F. H. (eds.) 2008. Sistemática, biogeografía y conservación de las hormigas cazadoras de Colombia. Bogotá: Instituto de Investigación de Recursos Biológicos Alexander von Humboldt, xiv + 609 pp.
  • Fernández F., and E. E. Palacio. 1995. Hormigas de Colombia IV: nuevos registros de géneros y especies. Caldasia 17: 587-596.
  • Fernández F., and T. M. Arias-Penna. 2008. Las hormigas cazadoras en la región Neotropical. Pp. 3-39 in: Jiménez, E.; Fernández, F.; Arias, T.M.; Lozano-Zambrano, F. H. (eds.) 2008. Sistemática, biogeografía y conservación de las hormigas cazadoras de Colombia. Bogotá: Instituto de Investigación de Recursos Biológicos Alexander von Humboldt, xiv + 609 pp.
  • Fernández, F. and S. Sendoya. 2004. Lista de las hormigas neotropicales. Biota Colombiana Volume 5, Number 1.
  • Gotwald W. H., Jr., and W. L. Brown, Jr. 1967. The ant genus Simopelta (Hymenoptera: Formicidae). Psyche (Camb.) 73: 261-277.
  • Kempf, W.W. 1972. Catalago abreviado das formigas da regiao Neotropical (Hym. Formicidae) Studia Entomologica 15(1-4).
  • Wheeler W. M. 1935. Ants of the genera Belonopelta Mayr and Simopelta Mann. Revista de Entomologia (Rio de Janeiro). 5: 8-19.