Nesomyrmex gracilis

AntWiki: The Ants --- Online
Nesomyrmex gracilis
Scientific classification
Kingdom: Animalia
Phylum: Arthropoda
Class: Insecta
Order: Hymenoptera
Family: Formicidae
Subfamily: Myrmicinae
Tribe: Crematogastrini
Genus: Nesomyrmex
Species group: angulatus
Species: N. gracilis
Binomial name
Nesomyrmex gracilis
Csösz & Fisher, 2016

Nesomyrmex gracilis casent0107191 p 1 high.jpg

Nesomyrmex gracilis casent0107191 d 1 high.jpg

Specimen Labels

This species is endemic to the Malagasy region, and its distribution is restricted to the northern, dry area of Madagascar in various habitats: rainforests, rainforest edges, littoral forests, and tropical dry forests.


Csősz and Fisher (2016) - A member of the angulatus species-group. Workers of N. gracilis differ from those of Nesomyrmex clypeatus by having no median clypeal notch and from Nesomyrmex angulatus by the lack of an anterolateral pronotal corner. This species can be separated from Nesomyrmex bidentatus and Nesomyrmex fragilis based on the apical spine distance ratio (SPTI/CS). This species occurs in the northern part of Madagascar syntopically with Nesomyrmex exiguus from the Nesomyrmex devius complex. A simple ratio (PoOC/SPTI, see details in key) offers 94.5% success in distinguishing between this species and N. exiguus, and a combination of two ratios (PoOC/SPTI and CWb/ML) yields a safe determination. The other two species of this complex, N. devius and Nesomyrmex hirtellus, do not occur syntopically with this species, as both are distributed far south of the range of N. gracilis.

Keys including this Species


Latitudinal Distribution Pattern

Latitudinal Range: -12.09949° to -14.2945°.

Tropical South

Distribution based on Regional Taxon Lists

Malagasy Region: Madagascar (type locality).

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.




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

  • gracilis. Nesomyrmex gracilis Csösz & Fisher, 2016: 27, figs. 12A-12C (w.q.m.) MADAGASCAR.

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



Body color: yellow; brown. Body color pattern: concolorous. Absolute cephalic size (mm): 620 [508, 699], (n D 44). Cephalic length vs. maximum width of head capsule (CL/CWb): 1.199 [1.154, 1.246]. Postocular distance vs. cephalic length (PoOc/CL): 0.387 [0.372, 0.406]. Postocular sides of cranium contour frontal view orientation: parallel; converging anteriorly. Postocular sides of cranium contour frontal view shape: straight; feebly convex; convex. Vertex contour line in frontal view shape: straight; feebly convex. Vertex sculpture: main sculpture rugose, ground sculpture areolate. Gena contour line in frontal view shape: convex. Genae contour from anterior view orientation: converging; strongly converging. Gena sculpture: rugoso-reticulate with areolate ground sculpture. Concentric carinae laterally surrounding antennal foramen: absent. Eye length vs. absolute cephalic size (EL/CS): 0.252 [0.228, 0.274]. Frontal carina distance vs. absolute cephalic size (FRS/CS): 0.413 [0.390, 0.436]. Longitudinal carinae on median region of frons: absent. Smooth median region on frons: absent. Antennomere count: 12. Scape length vs. absolute cephalic size (SL/CS): 0.647 [0.622, 0.685]. Facial area of the scape absolute setal angle: 0-15°. Median clypeal notch: absent. Ground sculpture of submedian area of clypeus: present. Median carina of clypeus: present. Lateral carinae of clypeus: present. Median anatomical line of propodeal spine angle value to Weber length in lateral view: 40-45°. Spine length vs. absolute cephalic size (SPST/CS): 0.399 [0.301, 0.446]. Minimum spine distance vs. absolute cephalic size (SPBA/CS): 0.393 [0.350, 0.433]. Apical spine distance vs. absolute cephalic size (SPTI/CS): 0.489 [0.448, 0.536]. Propodeal spine shape: straight; slightly bent. Anterolateral pronotal corner: absent. Metanotal depression: present. Dorsal region of mesosoma sculpture: rugulose with areolate ground sculpture. Lateral region of pronotum sculpture: areolate ground sculpture, superimposed by dispersed rugae. Mesopleuron sculpture: areolate ground sculpture superimposed by dispersed rugulae. Metapleuron sculpture: areolate ground sculpture superimposed by dispersed rugulae. Petiole width vs. absolute cephalic size (PEW/CS): 0.454 [0.390, 0.487]. Dorsal region of petiole sculpture: ground sculpture areolate, main sculpture dispersed rugose. Postpetiole width vs. absolute cephalic size (PPW/CS): 0.500 [0.453, 0.539]. Dorsal region of postpetiole sculpture: ground sculpture areolate, main sculpture dispersed rugose.

Type Material

Holotype worker: Madagascar: Prov. Antsiranana, Forêt Ambato, 26.6 km 33° Ambanja, 13° 27:87’S, 48° 33:10’E, 150 m, 8-11.xii.2004, collection code: BLF11548; CASENT0107191, Fisher et al. (CASENT0107191, California Academy of Sciences). Paratypes: three workers, three gynes, and a male with the same locality data. (CASC).


This name gracilis (=slender, slim) refers to the small, tiny appearance of this species.


  • Csosz, S. & Fisher, B.L. 2016. Taxonomic revision of the Malagasy members of the Nesomyrmex angulatus species group using the automated morphological species delineation protocol NC-PART-clustering. PeerJ 4:e1796 doi:10.7717/peerj.1796

References based on Global Ant Biodiversity Informatics

  • Goodman S., Y. Anbdou, Y. Andriamiarantsoa, B. L. Fisher, O. Griffiths, B. Keitt, J. J. Rafanomezantsoa, E. Rajoelison, J. C. Rakotonirina, L. Ranaivoarisoa et al. 2017. Results of a biological inventory of the Nosy Ankao island group, Parc National de Loky-Manambato, northeastern Madagascar. Malagasy Nature, Association Vahatra, 2017, 11, <>