Eurhopalothrix pilulifera

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Eurhopalothrix pilulifera
Scientific classification
Kingdom: Animalia
Phylum: Arthropoda
Class: Insecta
Order: Hymenoptera
Family: Formicidae
Subfamily: Myrmicinae
Tribe: Attini
Genus: Eurhopalothrix
Species: E. pilulifera
Binomial name
Eurhopalothrix pilulifera
Brown & Kempf, 1960

Eurhopalothrix pilulifera casent0280765 p 1 high.jpg

Eurhopalothrix pilulifera casent0280765 d 1 high.jpg

Specimen Labels

This is a very rare species and the known collections cover a number of widely-spaced localities. Specimens have been made in dry forest or second-growth wet forest habitats, all from Berlese or Winkler samples of forest floor litter and rotten wood. (Longino 2013)


A distinctive feature that is unique to E. pilulifera, at least among New World species, is an absence of differentiated setae projecting from the anterior margin of the scape. The dorsal surface of the scape is uniformly covered with scale-like, fully appressed setae. These setae also line the anterior edge but do not project on stalks or differ in any other way from those on the dorsal surface. All other species I have examined have projecting setae on the anterior margin. Eurhopalothrix pilulifera is most similar to Eurhopalothrix alopeciosa and Eurhopalothrix clypeata, sharing the small size; a similar arrangement and number of erect setae, these almost circular, nearly as broad as wide; and abundant ground pilosity that is strongly flattened and conspicuous. It has a simple clypeus, without an arcuate transverse carina (present in E. clypeata). The propodeal spine is in the form of a rectangular lamella extending down the posterior face of the propodeum (propodeal spine acute in E. alopeciosa, with narrow infradental lamella). Eurhopalothrix pilulifera may also be confused with Eurhopalothrix xibalba, which is larger and has thinner ground pilosity. (Longino 2013)

Keys including this Species


Latitudinal Distribution Pattern

Latitudinal Range: 21.366667° to -64.36°.

Tropical South

Distribution based on Regional Taxon Lists

Neotropical Region: Colombia, Costa Rica, Ecuador, El Salvador, Honduras, Mexico (type locality), Peru, Venezuela.

Distribution based on AntMaps


Distribution based on AntWeb specimens

Check data from AntWeb


Little is known about the biology of most species in this genus. Nests are rarely found, and queens and males have not been collected for many species. Longino (2013) summarized their biology "Eurhopalothrix specimens are encountered almost exclusively in samples from mass extraction techniques that recover small arthropods in sifted litter, rotten wood, and soil. Densities, at least in the northern Neotropics, are usually low, with workers occurring in < 10% of quantitative samples of 1 m2 litter plots, but occasionally may reach densities as high as 40% of samples. Live colonies of Old World Eurhopalothrix were observed by Wilson (1956) and Wilson and Brown (1984), and a Costa Rican colony of Basiceros manni was observed by Wilson and Hölldobler (1986). All basicerotines, including Eurhopalothrix, are thought to be predators in tropical leaf litter, relying on stealth or sit-and-wait techniques. Sampled specimens are often coated with a thin layer of clay, especially on the face, which is thought to function as camouflage, enhancing crypsis (Hölldobler & Wilson, 1986). Highly specialized spatulate setae may be instrumental in acquisition and adherence of the clay layer (Hölldobler & Wilson, 1986)."



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

  • pilulifera. Eurhopalothrix pilulifera Brown & Kempf, 1960: 208, fig. 38 (w.q.) MEXICO.

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

Longino (2013) - The holotype differs from the four other examined specimens in being slightly larger and having a relatively more elongate head (CI 89 versus 95–96). Brown and Kempf (1960) described a paratype queen from Rio de Janeiro, Brazil. This record should be considered suspect, pending fuller characterization of the fauna in southern Brazil.



Longino (2013) - HW 0.53–0.58, HL 0.56–0.64, SL 0.35–0.40, SLL 0.08–0.11, CI 89–97, SLI 21–28 (n=4–5). Labrum anteriorly bilobed, possibly shaped like labrum of E. xibalba (based on partial view, specimen with closed mandibles); mandible short, triangular, dorsal surface strongly convex, apical half strongly down-curved, surface punctate, rounding into ventral surface; masticatory margin not observed clearly but partial view shows two tooth rows, an outer row of flattened, triangular teeth and an inner row of several longer needle-shaped teeth; scape with very strongly developed basal lobe; scrobe deep, sharply delimited dorsally and ventrally, abutting deep antennal socket; surface of scrobe feebly foveolate; eye minute, comprising 1–3 fused ommatidia; clypeus minutely and shallowly punctate, shallowly convex medially, with shallow circular concavities anterolaterally, cuticle of these concavities transparent, contrasting with surrounding opaque cuticle; sides of head above eyes angulate, vertex margin strongly concave; surface of face uniformly convex, minutely and densely punctate; occipital carina distinct; undersurface of head uniformly punctate; postgenal suture visible as a longitudinal dark line.

Promesonotal profile low, shallowly convex, posterior margin a short step dropping to sloping, flat dorsal face of propodeum; metanotal groove not impressed; dorsal and posterior faces of propodeum distinct, meeting at obtuse angle, dorsal face subequal in length to posterior face; propodeal spine laminar, translucent, in the form of a broad foliaceous lamella, upper margin right-angled, lamella extending down posterior face to propodeal lobe; propodeal spiracle small, directed somewhat posteriorly; entire mesosoma minutely and densely punctate. Petiolar peduncle joins anterior face of petiolar node at a sharp (not rounded) obtuse angle; anterior face of node meets dorsal face at blunt right to slightly acute angle; posterior face of node short; ventral margin of petiole with large, blunt anteroventral tooth; postpetiole low and broad, with a feeble longitudinal sulcus dorsally; first gastral sternite lacking anterior sagittal keel; petiole, postpetiole, and gaster minutely and densely punctate.

Dorsal surface of scape uniformly covered with broadly spatulate, fully appressed ground pilosity; setae on leading edge of scape similar to dorsal pilosity, fully appressed and not at all projecting; ground pilosity on clypeus obsolete; ground pilosity of face conspicuous, ground setae decumbent, pompon-like, similar in form to the larger specialized projecting setae, but much smaller, about 1/4 the size, uniformly distributed across face (including frontal lobes) or sparser medially, denser peripherally; projecting specialized setae large, strongly pompon-like, full complement 18, with curved anterior row of 8, transverse median row of 4, and posterior row of 6 on vertex margin; dorsal promesonotum, dorsa of petiolar node and postpetiole, and first gastral tergite with ground pilosity similar to face; 3 pairs projecting pompon-like setae on promesonotum; legs with dense, strongly flattened, decumbent setae on apices of femora, posterior face of foretibia, entire midtibia, anterior face of hindtibia, somewhat sparser on other surfaces; setae at apices of tibiae not distinctly larger or differentiated from more proximal setae; basitarsus and remaining tarsomeres with abundant, strongly spatulate setae; two large pompon-like setae on hind margin of dorsal face of petiolar node; row of 4 pompon-like setae on hind margin of postpetiole, median pair only slightly smaller than lateral pair; specialized setae of first gastral tergite pompon-like, full complement about 20, distributed across entire tergite and along posterior margin, medial setae in two longitudinal rows of 5 pairs.

Color orange.

Type Material

Holotype worker: Mexico, Tabasco: Chichicastle, 16 Aug 1945, in berlesate (F. Bonet, No. 1108) Museum of Comparative Zoology (not examined). Paratype queen: Brazil, Rio de Janeiro, 18 Mar 1932 (H. Souza Lopes) Museu de Zoologia da Universidade de Sao Paulo.


  • Brown, W. L., Jr.; Kempf, W. W. 1960. A world revision of the ant tribe Basicerotini. Stud. Entomol. (n.s.) 3: 161-250 (page 208, fig. 38 worker, queen described)
  • Longino J. T. 2013. A review of the Central American and Caribbean species of the ant genus Eurhopalothrix Brown and Kempf, 1961 (Hymenoptera, Formicidae), with a key to New World species. Zootaxa. 3693:101-151. doi:10.11646/zootaxa.3693.2.1

References based on Global Ant Biodiversity Informatics

  • Del Toro, I., M. Vázquez, W.P. Mackay, P. Rojas and R. Zapata-Mata. Hormigas (Hymenoptera: Formicidae) de Tabasco: explorando la diversidad de la mirmecofauna en las selvas tropicales de baja altitud. Dugesiana 16(1):1-14.
  • Fernandes I., and J. de Souza. 2018. Dataset of long-term monitoring of ground-dwelling ants (Hymenoptera: Formicidae) in the influence areas of a hydroelectric power plant on the Madeira River in the Amazon Basin. Biodiversity Data Journal 6: e24375.
  • Fernandes, P.R. XXXX. Los hormigas del suelo en Mexico: Diversidad, distribucion e importancia (Hymenoptera: Formicidae).
  • Kempf, W.W. 1972. Catalago abreviado das formigas da regiao Neotropical (Hym. Formicidae) Studia Entomologica 15(1-4).
  • Longino J. T. 2013. A review of the Central American and Caribbean species of the ant genus Eurhopalothrix Brown and Kempf, 1961 (Hymenoptera, Formicidae), with a key to New World species. Zootaxa 3693(2): 101-151.
  • Palacio G., E.E. and F. Fernandez. 1995. Hormigas de Colombia V: Neuvos registros. Tacaya 4:6-7
  • Vasquez-Bolanos M. 2011. Checklist of the ants (Hymenoptera: Formicidae) from Mexico. Dugesiana 18(1): 95-133.
  • Vásquez-Bolaños M. 2011. Lista de especies de hormigas (Hymenoptera: Formicidae) para México. Dugesiana 18: 95-133