Strumigenys probatrix

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Strumigenys probatrix
Scientific classification
Kingdom: Animalia
Phylum: Arthropoda
Class: Insecta
Order: Hymenoptera
Family: Formicidae
Subfamily: Myrmicinae
Tribe: Attini
Genus: Strumigenys
Species: S. probatrix
Binomial name
Strumigenys probatrix
(Brown, 1964)

Strumigenys probatrix casent0281993 p 1 high.jpg

Strumigenys probatrix casent0281993 d 1 high.jpg

Specimen Labels

Occurs in wet forest habitats. I collected the species from Winkler samples of forest floor leaf litter in Monteverde and Hitoy Cerere. Uli Wagner collected a dealate queen in her study of forest floor litter fauna of La Selva Biological Station. At 1070m in the Zona Protectora of Braulio Carrillo National Park, a cloud forest habitat, I found an interesting co-occurrence of this and two other ant species. I looked beneath an epiphyte mat in a treefall, and found what appeared to be two contiguous nests, one of Cyphomyrmex salvini complex, and one of Strumigenys nevermanni. The disturbance to the epiphyte mat had jumbled them together, and I collected a series of both species into a vial. Upon examining the vial later, I discovered three workers of P. probatrix in addition to more abundant workers of Cyphomyrmex and Strumigenys. Could this indicate something special about the nesting habits of probatrix? (Longino, Ants of Costa Rica)


Bolton (2000) - A member of the Strumigenys probatrix-group. Differences separating this species from Strumigenys doryceps, the only other known member of the group, are tabulated in the identification section of this other ant.

Longino (Ants of Costa Rica) - Mandibles in side view straight, not broadly curved ventrally; mandibles relatively short, subtriangular, much of the apical portion meeting along a serially toothed masticatory margin when closed (former Smithistruma); leading edge of the scape with simple straight hairs present, projecting apically, not toward base of scape; color brown-black; face punctate; sides of posterior half of mesosoma completely and densely punctulate; head very elongate, CI 55-61; disc of postpetiole smooth and shining.

Keys including this Species


Latitudinal Distribution Pattern

Latitudinal Range: 18.5333° to 8.785°.

Tropical South

Distribution based on Regional Taxon Lists

Neotropical Region: Costa Rica, Guatemala, Honduras, Mexico (type locality), Panama.

Distribution based on AntMaps


Distribution based on AntWeb specimens

Check data from AntWeb


Strumigenys were once thought to be rare. The development and increased use of litter sampling methods has led to the discovery of a tremendous diversity of species. Many species are specialized predators (e.g. see Strumigenys membranifera and Strumigenys louisianae). Collembola (springtails) and other tiny soil arthropods are typically favored prey. Species with long linear mandibles employ trap-jaws to sieze their stalked prey (see Dacetine trap-jaws). Larvae feed directly on insect prey brought to them by workers. Trophallaxis is rarely practiced. Most species live in the soil, leaf litter, decaying wood or opportunistically move into inhabitable cavities on or under the soil. Colonies are small, typically less than 100 individuals but in some species many hundreds. Moist warm habitats and micro-habitats are preferred. A few better known tramp and otherwise widely ranging species tolerate drier conditions. Foraging is often in the leaf litter and humus. Workers of many species rarely venture above ground or into exposed, open areas. Individuals are typically small, slow moving and cryptic in coloration. When disturbed individuals freeze and remain motionless. Males are not known for a large majority of species.



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

  • probatrix. Smithistruma probatrix Brown, 1964a: 186, pl. 16, fig. 3 (w.) MEXICO. Combination in Pyramica: Bolton, 1999: 1673; in Strumigenys: Baroni Urbani & De Andrade, 2007: 126. See also: Bolton, 2000: 212.

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



Holotype TL 2.7, HL 0.67, HW 0.41 CCI 61), ML 0.17 (MI 25), WL 0.72, antennal scape L 0.36, funiculus L 0.67, apical funicular segment L 0.33 mm.

A slender, long-legged species with head and mandibles drawn out to an unusual length in front, and the antennae correspondingly elongate; otherwise a rather typical member of Smithistruma.

Head and mandibles as in Fig.; note the extremely long, low basal lamella of the mandible, the virtual lack of a diastema, and the brief series of teeth. Mandibles porrect as seen from the side, only very slightly down-curved at the apex. Clypeus convex from side to side, but only very slightly so from front to rear, with a distinct median tumulus that is shining anteriorly. Antennae elongate, especially the apical and penultimate segments of the funiculus, the penultimate thickest; segment III about as broad as long.

Gula weakly convex; postoral region with a gentle concavity reaching from side to side, but this scarcely constitutes a postoral groove. Alitrunk long and slender, the promesonotum forming one long convexity in profile, sloping gently down posteriad to meet the horizontal, feebly convex propodeal dorsum at a weakly impressed metanotal group. Propodeal teeth short, acutely triangular, subtended each by a distinct propodeal lamella that is concave above and convex below.

Propodeum with an elongate node (longer than high, longer than broad, slightly longer than its anterior peduncle) with voluminous posterolateral and moderate ventral spongiform appendages. Postpetiolar disc subcircular, truncate in front as seen from above, slightly broader than petiolar node and slightly broader than long, with voluminous spongiform appendages in all the normal positions. Gaster with a short anteroventral spongiform beard and an anterodorsal spongiform fringe, from which extends a small number of very short longitudinal dorsal postulae; gaster otherwise smooth and shining.

Rest of body densely reticulopunctate and opaque, except for a small, sparsely pundulate central patch on the mesopleuron, which is more or less shining. Mandibles, antennae and legs finely and densely punctulate, opaque.

Ground pilosity consisting of short, curved reclinate, fine hairs with blunt or pointed tips, abundant and forming an almost wooly covering over the promesonotum, less abundant on the head, propodeum, petiolar node, mandibles and appendages; absent on post petiole and gaster. Clypeal hairs short, sparse, reclinate over disc, directed anterolaterad; fringing hairs short and inconspicuous. Specialized erect hairs long and finely flagelliform: a pair on the lateral borders of the occipital lobes and another pair between these on the vertex; a humeral pair and another pair astride the mesonotum; 2 or 3 pairs each on the two nodes; about 20-24 hairs on the gaster, with a few shorter ones a1so beneath the gastric apex. Last two antennal segments with a number of conspicuous curved subreclinate hairs.

Color deep brownish-red, gaster darkest; mandibles and appendages a trifle lighter and more yellowish.

Bolton (2000) - TL 2.7-3.0, HL 0.67-0.82, HW 0.41-0.45, CI 55-61, ML 0.17-0.18, MI 22-25, SL 0.36-0.42, SI 88-93, PW 0.30-0.34, AL 0.72-0.88 (5 measured).

Antennal club segments long, combined length of funicular segments 4 and 5 ca 0.60, greater than the SL. Fourth (preapical) funicular segment somewhat swollen, broader than the apical antennomere and broader than the scape. Legs relatively long, hind femur 0.58-0.64; bullae of femoral and tibial glands conspicuous. Node of petiole in profile with length of dorsum greater than height of anterior face. Disc of postpetiole in dorsal view narrowly bordered with spongiform tissue on all sides. Margins of clypeus fringed with short spatulate hairs that are shallowly curved; clypeal dorsum with minute spatulate hairs. Dorsum of head with a single pair of long vertical flagellate hairs that arise just behind highest point of vertex. Cephalic dorsum and sides reticulate-punctate everywhere, the clypeus less strongly so than the remainder; small median tumulus of clypeus more or less smooth and clypeal margin anteromedially ending in a blunt poi nt. Dorsal alitrunk, declivity of propodeum and sides of alitrunk densely reticulate-punctate everywhere except for a smooth area on the katepisternum. Petiole and postpetiole reticulate-punctate, the latter sometimes with a small smooth area anteromedially and with traces of longitudinal organisation of sculpture centrally on disc. First gastral tergite highly polished and glassy smooth , basigastral costulae very short and restricted to extreme base of sc1erite.

Type Material

Bolton (2000) - Holotype worker, MEXICO: Chiapas, Ocosingo, 1950, Berlese funnel sample (c. & M. Goodnight & L. J. Stannard) (Museum of Comparative Zoology) [examined].


References based on Global Ant Biodiversity Informatics

  • Bolton, B. 2000. The Ant Tribe Dacetini. Memoirs of the American Entomological Institute 65
  • Dattilo W. et al. 2019. MEXICO ANTS: incidence and abundance along the Nearctic-Neotropical interface. Ecology
  • Fernandes, P.R. XXXX. Los hormigas del suelo en Mexico: Diversidad, distribucion e importancia (Hymenoptera: Formicidae).
  • Fernández, F. and S. Sendoya. 2004. Lista de las hormigas neotropicales. Biota Colombiana Volume 5, Number 1.
  • Kempf, W.W. 1972. Catalago abreviado das formigas da regiao Neotropical (Hym. Formicidae) Studia Entomologica 15(1-4).
  • Longino J. T. 2013. Ants of Nicargua. Consulted on 18 Jan 2013.
  • Longino J. T. L., and M. G. Branstetter. 2018. The truncated bell: an enigmatic but pervasive elevational diversity pattern in Middle American ants. Ecography 41: 1-12.
  • Longino J. T., and N. M. Nadkarni. 1990. A comparison of ground and canopy leaf litter ants (Hymenoptera: Formicidae) in a Neotropical montane forest. Psyche (Cambridge) 97: 81-94.
  • Longino J. T., and R. K. Colwell. 2011. Density compensation, species composition, and richness of ants on a neotropical elevational gradient. Ecosphere 2(3): 16pp.
  • Longino J. et al. ADMAC project. Accessed on March 24th 2017 at
  • Sosa-Calvo J., S. O. Shattuck, and T. R. Schultz. 2006. Dacetine ants of Panama: new records and description of a new species. Proceedings of the Entomological Society of Washington 108: 814-821.
  • Vásquez-Bolaños M. 2011. Lista de especies de hormigas (Hymenoptera: Formicidae) para México. Dugesiana 18: 95-133