Thaumatomyrmex atrox

Identification
Kempf (1975) - The presence of a basal denticle on mandibles, the semicircular rugulae between frontal carinae and eyes, and the shallow, circular depression on posterior surface of petiolar node still allow for a clear-cut separation of atrox from Thaumatomyrmex ferox.

Distribution based on Regional Taxon Lists
Neotropical Region: Colombia, Costa Rica, Guyana, Panama, Venezuela.

Nomenclature

 * . Thaumatomyrmex atrox Weber, 1939a: 98, fig. 3 (w.) GUYANA, TRINIDAD.
 * Type-material: holotype worker, 1 paratype worker.
 * Type-locality: holotype Guyana (“British Guiana”): Kartabo Point, junction of Mazaruni and Cuyuni Rivers, 20.viii.1935 (N.A. Weber); paratype Trinidad: foothills N Tunapuna, 29.vii.1935 (N.A. Weber).
 * Type-depository: MCZC.
 * Status as species: Weber, 1942b: 67; Smith, M.R. 1944b: 98 (in key); Kempf, 1972a: 250; Kempf, 1975b: 122 (redescription); Longino, 1988: 38; Brandão, 1991: 382; Brandão, Diniz & Tomotake, 1991: 339; Bolton, 1995b: 420; Mackay, Mackay, et al. 2008: 212; Jahyny, et al. 2008: 333; Bezděčková, et al. 2015: 125; Fernández & Guerrero, 2019: 548.
 * Distribution: Colombia, Guyana, Peru, Trinidad.

Worker
Kemp (1975): paratype. TL 4.4 mm; HL 0.91 mm; HW 1.09 mm; CI 120; ML 1.15 mm; MI 126; IfW 0.65 mm; IfI 60; SL 0.80 mm; SI 88; WL 1.33 mm; PnW 0.64 mm; HfL 0.97 mm; HfI 89; PW 0.73 mm. Extremely close to ferox from which it differs in the following characters:

Head slightly narrower (CI) and mandibles somewhat shorter (MI). The mandibles with a small tooth at base of proximal spine, the intermediate spine not sinuous, almost as long as one half the chord length of apical spine. Rugulae on frontal lobes prolonged caudad by curving laterad towards upper (inner) border of eyes and circumscribing the antennal socket. Greatest length of head both between anteriormost point of frontal lobes and of mandibular acetabula and the posteriormost point of occipital carina. Petiole with the anterior surface of node transversely convex, in profile almost straight (Fig. 26), apex medium rounded, posterior surface as seen from above concave, as seen from the side somewhat convex, showing on its disc a large, shallow circular depression.

Facet count across greatest diameter of eyes: 12 facets in a row. Metanotal groove present. Thorax as in ferox.

Type Material
Kemp (1975): GUIANA: junction of the Mazaruni and Cuyuni rivers, August 20, 1935, among leaves, N. A. Weber leg. 1 female (holotype, Weber collection: ). Trinidad: foothills north of Tunapuna, July 29, 1935, among leaves, N. A. Weber leg. 1 female (paratype: WWK, received from ); paratype examined.

References based on Global Ant Biodiversity Informatics

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 * Basset Y., L. Cizek, P. Cuenoud, R. K. Didham, F. Guilhaumon, O. Missa, V. Novotny, F. Odegaards, T. Roslin, J. Schmidl et al. 2012. Arthropod diversity in a tropical forest. Science 338(6113): 1481-1484.
 * Brandao, C.R.F. 1991. Adendos ao catalogo abreviado das formigas da regiao neotropical (Hymenoptera: Formicidae). Rev. Bras. Entomol. 35: 319-412.
 * Dattilo W. et al. 2019. MEXICO ANTS: incidence and abundance along the Nearctic-Neotropical interface. Ecology https://doi.org/10.1002/ecy.2944
 * Delabie J. H. C., D. Fresneau, and A. Pezon. 2000. Notes on the ecology of Thaumatomyrmex spp. (Hymenoptera: Formicidae: Ponerinae) in Southeast Bahia, Brazil. Sociobiology 36(3): 571-584.
 * Donoso D. A. 2014. Assembly mechanisms shaping tropical litter ant communities. Ecography 37 doi: 10.1111/j.1600-0587.2013.00253.x
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 * Fernández F. 2008. Subfamilia Ponerinae s.str. Pp. 123-218 in: Jiménez, E.; Fernández, F.; Arias, T.M.; Lozano-Zambrano F. H. (eds.) 2008. Sistemática, biogeografía y conservación de las hormigas cazadoras de Colombia. Bogotá: Instituto de Investigación de Recursos Biológicos Alexander von Humboldt, xiv + 609 pp.
 * Fernández F., E. E. Palacio, W. P. MacKay, and E. S. MacKay. 1996. Introducción al estudio de las hormigas (Hymenoptera: Formicidae) de Colombia. Pp. 349-412 in: Andrade M. G., G. Amat García, and F. Fernández. (eds.) 1996. Insectos de Colombia. Estudios escogidos. Bogotá: Academia Colombiana de Ciencias Exactas, Físicas y Naturales, 541 pp
 * Fernández, F. and S. Sendoya. 2004. Lista de las hormigas neotropicales. Biota Colombiana Volume 5, Number 1.
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 * INBio Collection (via Gbif)
 * Jahyny B., S. Lacau, J. H. C. Delabie, and D. Fresneau. 2008. Le genre Thaumatomyrmex Mayr 1887, cryptique et prédateur spécialiste de Diplopoda Penicillata. Pp. 329-346 in: Jiménez, E.; Fernández, F.; Arias, T.M.; Lozano-Zambrano, F. H. (eds.) 2008. Sistemática, biogeografía y conservación de las hormigas cazadoras de Colombia. Bogotá: Instituto de Investigación de Recursos Biológicos Alexander von Humboldt, xiv + 609 pp.
 * Kempf W. W. 1975. A revision of the Neotropical ponerine ant genus Thaumatomyrmex Mayr (Hymenoptera: Formicidae). Studia Entomologica 18: 95-126.
 * Kempf, W.W. 1972. Catalago abreviado das formigas da regiao Neotropical (Hym. Formicidae) Studia Entomologica 15(1-4).
 * Longino J. T. 1988. Notes on the taxonomy of the neotropical ant genus Thaumatomyrmex Mayr (Hymenoptera: Formicidae). Pp. 35-42 in: Trager, J. C. (ed.) 1988. Advances in myrmecology. Leiden: E. J. Brill, xxvii + 551 pp.
 * 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.
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 * Longino J. et al. ADMAC project. Accessed on March 24th 2017 at https://sites.google.com/site/admacsite/
 * Lozano-Zambrano F. H., E. Jimenez, T. M. Arias-Penna, A. M. Arcila, J. Rodriguez, and D. P. Ramirez. 2008. Biogeografía de las hormigas cazadoras de Colombia. Pp. 349-406. in: Jiménez, E.; Fernández, F.; Arias, T.M.; Lozano-Zambrano, F. H. (eds.) 2008. Sistemática, biogeografía y conservación de las hormigas cazadoras de Colombia. Bogotá: Instituto de Investigación de Recursos Biológicos Alexander von Humboldt, xiv + 609 pp.
 * Mirmecofauna de la reserva ecologica de San Felipe Bacalar
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 * Scott-Santos, C.P., F.A. Esteves, C.R.F. Brandao. 2008. Catalogue of "Poneromorph" ant type specimens (Hymenoptera, Formicidae) deposited in the Museu de Zoologia da Universidade de Sao Paulo, Brazil. Papeis Avulsos de Zoologia 48(11):75-88.
 * Silva R.R., and C. R. F. Brandao. 2014. Ecosystem-Wide Morphological Structure of Leaf-Litter Ant Communities along a Tropical Latitudinal Gradient. PLoSONE 9(3): e93049. doi:10.1371/journal.pone.0093049
 * Smith M. R. 1944. Ants of the genus Thaumatomyrmex Mayr with the description of a new Panamanian species (Hymenoptera: Formicidae). Proceedings of the Entomological Society of Washington 46: 97-99.
 * Weber N. A. 1939. New ants of rare genera and a new genus of ponerine ants. Ann. Entomol. Soc. Am. 32: 91-104.
 * Weber N. A. 1942. The genus Thaumatomyrmex Mayr with description of a Venezuelan species (Hym.: Formicidae). Bol. Entomol. Venez. 1: 65-71.