Pseudomyrmex nigrocinctus

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Pseudomyrmex nigrocinctus
Scientific classification
Kingdom: Animalia
Phylum: Arthropoda
Class: Insecta
Order: Hymenoptera
Family: Formicidae
Subfamily: Pseudomyrmecinae
Genus: Pseudomyrmex
Species group: ferrugineus
Species: P. nigrocinctus
Binomial name
Pseudomyrmex nigrocinctus
(Emery, 1890)

Pseudomyrmex nigrocinctus casent0005795 profile 1.jpg

Pseudomyrmex nigrocinctus casent0005795 dorsal 1.jpg

Specimen labels


An obligate acacia mutualist that can inhabit a few different species of Vachellia


Ward (1993) - Workers and queens of P. nigrocinctus are easily distinguished from all other acacia ants, except Pseudomyrmex particeps (see below), by their small size (HW < 0.86 in both castes), elongate head in the worker (worker CI < 0.85), and narrow petiole and postpetiole (worker PWI3 0.50, worker PPWI 1.30, queen PWI2 0.57-0.63). The orange color and short eyes are also characteristic.


Guatemala to Costa Rica, with most records coming from the southern end of its range.

Latitudinal Distribution Pattern

Latitudinal Range: 15.1333° to 9.8667°.

Tropical South

Distribution based on Regional Taxon Lists

Neotropical Region: Costa Rica (type locality), El Salvador, French Guiana, Guatemala, Guyana, Nicaragua, Suriname.

Distribution based on AntMaps


Distribution based on AntWeb specimens

Check data from AntWeb

Countries Occupied

Number of countries occupied by this species based on AntWiki Regional Taxon Lists. In general, fewer countries occupied indicates a narrower range, while more countries indicates a more widespread species.


Estimated Abundance

Relative abundance based on number of AntMaps records per species (this species within the purple bar). Fewer records (to the left) indicates a less abundant/encountered species while more records (to the right) indicates more abundant/encountered species.



Ward (1993) - Colonies are monogynous, and have been collected from Acacia collinsii, A. cornigera and A. hindsii. Records from Acacia gentlei and A. globulifera (Beulig & Janzen 1969: 59) need to be confirmed because of possible confusion with Pseudomyrmex peperi. Janzen's (1967b) observations on "P. nigrocincta" in Mexico refer to P. peperi. On the other hand descriptions of the biology and behavior of P. nigrocinctus in Costa Rica (Janzen 1973, 1974, 1975, 1983; Beulig & Janzen 1969) are reliably attributed to P. nigrocinctus.

Amador-Vargas (2019) found that Pseudomyrmex spinicola made larger clearings around the trees they occupied than Pseudomyrmex flavicornis and Pseudomyrmex nigrocinctus. Pseudomyrmex spinicola workers also pruned thicker vegetative tissue, and their workers had broader heads - presumed to allow more robust pruning due to larger muscles in the head providing greater mandibular force. More generally, this study and its findings are unusual in examining plant pruning differences provided by ants involved in acacia mutalisms. Most studies of ant-provided benefits to plants in these ant-plant mutualisms focus on herbivory.

Life History Traits

  • Queen number: monogynous (Rissing and Pollock, 1988; Frumhoff & Ward, 1992)



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

  • nigrocinctus. Pseudomyrma nigrocincta Emery, 1890b: 64, pl. 6, fig. 3 (w.q.) COSTA RICA. [Also described as new by Emery, 1894k: 52.] Combination in Pseudomyrmex: Kempf, 1972a: 221. Senior synonym of alfari, bicincta, peltata: Ward, 1993: 144.
  • alfari. Pseudomyrma alfari Forel, 1906d: 228 (w.) COSTA RICA. Combination in Pseudomyrmex: Kempf, 1972a: 215. Junior synonym of nigrocinctus: Ward, 1993: 145.
  • bicincta. Pseudomyrma nigrocincta var. bicincta Santschi, 1922b: 347 (w.) COSTA RICA. Combination in Pseudomyrmex: Kempf, 1972a: 221. Junior synonym of nigrocinctus: Ward, 1993: 145.
  • peltata. Pseudomyrma peltata Menozzi, 1927c: 273, fig. 2 (w.m.) COSTA RICA. Combination in Pseudomyrmex: Kempf, 1972a: 222. Junior synonym of nigrocinctus: Ward, 1993: 145.

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


Ward (1993) - Worker measurements (n =21). —HL 0.89- 1.08, HW 0.74-0.85, MFC 0.035-0.051 , CI 0.75-0.84, REL 0.40-0.45, REL2 0.51-0.56, OOI 1.39-2.76, VI 0.62-0.78, FCI 0.044-0.065, SI 0.44-0.48, SI2 0.81-0.89, NI 0.58-0.64, PLI 0.59-0.68, PWI 0.49-0.61, PPWI 1.10-1.30.

Worker diagnosis. —Small species with elongate head and short eyes (REL O.45, REL2 0.56, EL/LHT 0.61). Palp formula 5,3. Median clypeal lobe rather narrow, its surface and anterior margin convex. Frontal carinae separated by about basal scape width (FCI 0.055). Metanotal groove well marked; basal and declivitous faces of Propodeum subequal. Petiole short (PLI > 0.57), its anterior peduncle broad in dorsal view (PWI3 0.50-0.61) and not well differentiated from the node. Petiole lacking expanded posterolateral corners. Postpetiole less broad than in most other species in the P. ferrugineus group (see PPWI values). Head densely punctulate and subopaque, becoming sublucid posteriorly where the punctulae are separated by shiny interspaces. Mesosoma punctulate to (laterally) coriarious-imbricate, sublucid, becoming subopaque on the propodeum. Standing pilosity moderately common; pubescence dense and closely appressed. Orange-brown, often with anterolateral fuscous patches on abdominal tergite IV (these form a distinct transverse black band in queens).

Type Material

Ward (1993):

Syntype workers, queens, males, Alajuela, Costa Rica (A. Alfaro) (The Natural History Museum, Museo Civico di Storia Naturale, Genoa, Museum of Comparative Zoology, Musee d'Histoire Naturelle Genève) [Examined]. One syntype worker from MCSN here designated LECTOTYPE.

Pseudomyrma alfari Forel 1906:228. Two syntype workers, Tivives, embouchure de Jesus-Maria, Costa Rica (A. Alfaro) (MHNG) [Examined]. One syntype here designated LECTOTYPE.

Pseudomyrma nigrocinta var. bicincta Santschi 1922: 347. Syntype workers, Costa Rica (MHNG, NHMB) [Examined]. One syntype from NHMB here designated LECTOTYPE.

Pseudomyrma peltata Menozzi 1927a:273. Three syntype workers, San Jose, Costa Rica (H. Schmidt) (NHMB) [Examined].


References based on Global Ant Biodiversity Informatics

  • Baroni Urbani C. 1977. Katalog der Typen von Formicidae (Hymenoptera) der Sammlung des Naturhistorischen Museums Basel (2. Teil). Mitt. Entomol. Ges. Basel (n.s.) 27: 61-102.
  • Emery C. 1890. Studii sulle formiche della fauna neotropica. Bull. Soc. Entomol. Ital. 22: 38-8
  • Enzmann E. V. 1944. Systematic notes on the genus Pseudomyrma. Psyche (Camb.) 51: 59-103.
  • Fernández, F. and S. Sendoya. 2004. Lista de las hormigas neotropicales. Biota Colombiana Volume 5, Number 1.
  • Forel A. 1906. Fourmis néotropiques nouvelles ou peu connues. Annales de la Société Entomologique de Belgique 50: 225-249.
  • INBio Collection (via Gbif)
  • 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.
  • Santschi F. 1922. Myrmicines, dolichodérines et autres formicides néotropiques. Bulletin de la Société Vaudoise des Sciences Naturelles 54: 345-378.
  • Smith M. A., W. Hallwachs, D. H. Janzen. 2014. Diversity and phylogenetic community structure of ants along a Costa Rican elevational gradient. Ecography 37(8): 720-731.
  • Ward P. S. 1990. The Ant Subfamily Pseudomyrmecinae (Hymenoptera: Formicidae): Generic Revision and Relationship to Other Formicids. Systematic Entomology 15: 449-489
  • Ward, P.S. 1993. Systematic studies on Pseudomyrmex acacia-ants (Hymenoptera: Formicidae) Journal of Hymenoptera Research 2(1):117-168
  • Wheeler W. M. 1942. Studies of Neotropical ant-plants and their ants. Bulletin of the Museum of Comparative Zoology 90: 1-262.