Megalomyrmex osadrifti

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Megalomyrmex osadrifti
Scientific classification
Kingdom: Animalia
Phylum: Arthropoda
Class: Insecta
Order: Hymenoptera
Family: Formicidae
Subfamily: Myrmicinae
Tribe: Solenopsidini
Genus: Megalomyrmex
Species group: pusillus
Species: M. osadrifti
Binomial name
Megalomyrmex osadrifti
Boudinot, Sumnicht & Adams, 2013

Megalomyrmex osadrifti casent0630909 p 1 high.jpg

Megalomyrmex osadrifti casent0630909 d 1 high.jpg

Specimen Labels

Known from types collected from rainforest leaf litter.


Boudinot et al. (2013) - Worker uniquely identified among Central American Megalomyrmex as follows: (1) katepisternum smooth and shining; (2) mandibular teeth, excluding apical two, small and fine; (3) occipital carina not visible in full-face view; (4) eyes of normal development and relatively close to anterolateral corner of clypeus (EL > 0.12 mm, OMI < 60); (5) scapes relatively long (SI > 90); (6) dorsal and posterior faces of propodeum meeting at broad curve. Queen similarly identifiable as worker, but with less robust petiolar and postpetiolar nodes, alate.

Sympatric with Megalomyrmex drifti, it is separated from this species by having a distinct basal and masticatory mandibular margins and M. osadrifti also has a well-rounded propodeum and relatively long scapes, whereas M. drifti has a dorsolaterally marginate and more angular propodeum. Furthermore, M. osadrifti is often larger (ML usually > 0.70 mm, vs. ML usually < 0.70 mm). Separated from Megalomyrmex megadrifti by the propodeum shape and the relatively short malar space (OMI < 60).

Keys including this Species


Osa Peninsula (Puntarenas province) of Costa Rica; sea-level to 300 m elevation. Occurs in sympatry with M. drifti.

Latitudinal Distribution Pattern

Latitudinal Range: 8.7° to 8.40667°.

Tropical South

Distribution based on Regional Taxon Lists

Neotropical Region: Costa Rica (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.




Images from AntWeb

Megalomyrmex osadrifti casent0630911 h 1 high.jpgMegalomyrmex osadrifti casent0630911 h 2 high.jpgMegalomyrmex osadrifti casent0630911 p 1 high.jpgMegalomyrmex osadrifti casent0630911 d 1 high.jpgMegalomyrmex osadrifti casent0630911 l 1 high.jpg
Paratype Megalomyrmex osadriftiQueen (alate/dealate). Specimen code casent0630911. Photographer Brendon Boudinot, uploaded by California Academy of Sciences. Owned by MCZ.


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

  • osadrifti. Megalomyrmex osadrifti Boudinot, et al. 2013: 57, figs. 41, 155-158, 241 (w.q.) COSTA RICA.
    • Type-material: holotype worker, 3 paratype workers, 1 paratype queen.
    • Type-locality: holotype Costa Rica: Puntarenas, 13 km. SSW Pto Jimenez, 8.40667°N, 83.3283°W±200 m., 130 m., 10.iii.2008, #JTL 6209-49, tropical rainforest, sifted litter (J.T. Longino); paratypes: 3 workers with same data, 1 queen with same data but #JTL 6209-26.
    • Type-depositories: MCZC (holotype); BMNH, MCZC, MZSP, USNM (paratypes).
    • Distribution: Costa Rica.

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



(holotype): HW 0.50, HL 0.58, SL 0.53, OMD 0.08, EL 0.16, ML 0.77, CI 85, SI 91, EI 33, OMI 49. (n=5): HW 0.48–0.52, HL 0.56–0.61, SL 0.50–0.57, OMD 0.06–0.09, EL 0.15–0.16, ML 0.73–0.80, CI 83–86, SI 87–93, EI 31–33, OMI 40–57.

Head Palpal formula 3,2. Basal and masticatory margins of mandible distinct, demarcated by an angle with a small tooth. Mandible with 5–6 teeth; apical two teeth largest, apical tooth slightly longer than subapical; 3–4 basal teeth small, evenly spaced or sometimes crowded somewhat anteriorly, away from basal tooth. Dorsal surface of mandible smooth and shining, interrupted by weak piligerous punctae. Clypeus truncate in profile view, with median seta often raised on a small tubercle. Clypeal carinae present, weak, and parallel until near anterior edge of clypeus. Clypeus, between antennal insertions, narrower than maximum width of scape. Antennal fossa surrounded by 2–3 complete carinulae. Malar area roughened in anterior half, smooth posteriorly. Compound eye with several ocular setae. Compound eye relatively close to lateral clypeal margin (OMI < 40). Scapes relatively long (SI > 90). Occipital carina short, distinct; obscured by vertex in full-face view; extending anteroventrally less than one eighth length of postgenal bridge. Mesosoma Katepisternum, promesonotum, and propodeum smooth and shining, excluding 3–4 close-set metapleural carinulae. Metapleural carinulae not reaching meso-metapleural suture. Metanotum deeply incised. Foraminal carina incomplete dorsomedially. Meso- and metabasitarsi tubular. Metasoma Petiole and postpetiole predominantly smooth and shining, except for girdling carinulae around posterior bases. Subpetiolar process a broad, truncate denticle in profile view. Postpetiolar sternum weakly dentate anteriorly. Lancets of sting apparatus flattened, narrow, broadening apically. Setation Fine; head dorsum with somewhat dilute longer suberect to erect setae in addition to short appressed to decumbent setae; scape with appressed to suberect setae; promesonotum with about 12 setae on each lateral half, about half of these setae long; first gastric tergum with somewhat dilute long subdecumbent to suberect setae in addition to numerous short appressed setae. Head, meso- and metasoma black to dark red-brown; mandibles, antennae, and legs yellow-brown.


(n=2): HW 0.58–0.59, HL 0.65, SL 0.57–0.60, OMD 0.08, EL 0.20–0.21, ML 0.95–0.99, CI 0.90, SI 0.89–0.91, OMI 0.38–0.39.

Similar to worker; differing by presence of an alate-condition mesosoma, stronger sculpturation and more pronounced propodeal angle.

Type Material

Holotype worker COSTA RICA, Puntarenas: 13 km SSW Pto. Jimenez, 8.40667°N 83.3283°W ±200 m, 130 m, 10 Mar 2008, tropical rainforest, ex sifted leaf litter (J.T. Longino#JTL6209-49) [CASENT0630909, Museum of Comparative Zoology]. Paratype workers: (3) same data as holotype [CASENT0630907, The Natural History Museum; CASENT0630908, Museu de Zoologia da Universidade de Sao Paulo; CASENT0630910, National Museum of Natural History]. Paratype queen: (1) same data as holotype except #JTL6209-26 [CASENT0630911, MCZ].


This species is morphologically similar to Megalomyrmex drifti and the Osa Peninsula of Costa Rica is the type locality.


Boudinot, B.E., Sumnicht, T.P. & Adams, R.M.M. 2013. Central American ants of the genus Megalomyrmex Forel (Hymenoptera: Formicidae): six new species and keys to workers and males. Zootaxa 3732, 1-82.

References based on Global Ant Biodiversity Informatics

  • Boudinot B. E., T. P. Sumnicht, and R. M. M. Adams. 2013. Central American ants of the genus Megalomyrmex Forel (Hymenoptera: Formicidae): six new species and keys to workers and males. Zootaxa 3732(1): 1-82.
  • 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.