Thaumatomyrmex

AntWiki - Where Ant Biologists Share Their Knowledge
Jump to navigation Jump to search
Thaumatomyrmex
Thaumatomyrmex mutilatus
Scientific classification
Kingdom: Animalia
Phylum: Arthropoda
Class: Insecta
Order: Hymenoptera
Family: Formicidae
Subfamily: Ponerinae
Tribe: Ponerini
Alliance: Pachycondyla genus group
Genus: Thaumatomyrmex
Mayr, 1887
Type species
Thaumatomyrmex mutilatus
Diversity
13 species
(Species Checklist)

Thaumatomyrmex mutilatus casent0173034 profile 1.jpg

Thaumatomyrmex mutilatus

Thaumatomyrmex mutilatus casent0173034 dorsal 1.jpg

Specimen Label

Longino Ants of Costa Rica - The Neotropical ant genus Thaumatomyrmex is a myrmecologist's delight, being highly distinctive and rare. The mandibles are like pitch-forks, each mandible composed of three long tines joined at the base. Thaumatomyrmex workers are rarely encountered, and only a handful of specimens exist in the world's museums. They are most often collected as isolated workers in samples of leaf litter from the forest floor, extracted using Berlese funnels or Winkler sacks. Brandao et al. (1991) discovered that Thaumatomyrmex contumax and Thaumatomyrmex atrox in southern Brazil are specialist predators of millipedes in the order Polyxenida. Polyxenid millipedes are covered with detachable barbed setae which entangle potential predators. The Thaumatomyrmex workers use their long, specialized mandibles to capture polyxenids and subsequently strip them of their setae.

Identification

Schmidt and Shattuck (2014) - Thaumatomyrmex workers are among the most morphologically derived of all ponerines, and would be difficult to confuse with those of any other genus. Their pitchfork-like mandibles and widely separated frontal lobes are autapomorphic within Ponerini and immediately identify them as Thaumatomyrmex. Belonopelta and Emeryopone also have mandibles with long attenuated teeth, but their teeth are shorter than those of Thaumatomyrmex and their frontal lobes are closely approximated as is typical for Ponerini.

Keys including this Genus

 

Keys to Species in this Genus

Distribution

Distributed between Mexico and Northern Argentina, with occurrence in Caribbean islands (Jahyny et al., 2015).

Distribution and Richness based on AntMaps

Biology

Schmidt and Shattuck (2014) - Thaumatomyrmex displays an unusual suite of morphological, ecological and behavioral traits. Brandão et al. (1991) examined the feeding habits of Thaumatomyrmex atrox and Thaumatomyrmex contumax and found that they are highly specialized predators of polyxenid millipedes (confirmed by Delabie et al., 2000; see also the account in Hölldobler & Wilson, 1995).

Thaumatomyrmex contumax removal of setae from polyxenid millipede

Polyxenids are covered with protective hooked setae which hunting Thaumatomyrmex workers must deal with before consuming their prey. The ants deal with the polyxenids by grasping them with their pitchfork mandibles, stinging them (presumably to minimize defensive struggles), and finally scraping off the defensive setae using their modified front tarsi, rendering the millipedes palatable (Brandão et al., 1991). Given the highly specialized mandibular structure present in all Thaumatomyrmex species and the observation of millipede predation in two different species groups, polyxenid predation is probably universal in the genus. Thaumatomyrmex workers forage individually in leaf litter and feign death when disturbed (Brandão et al., 1991). Though Thaumatomyrmex were long considered to be rare (Longino, 1988), improved sampling methods have demonstrated that their colony density can be very high (Delabie et al., 2000). Given the cryptobiotic foraging habits of Thaumatomyrmex, the function of the large well-developed eyes in the workers is a mystery (Baroni Urbani & de Andrade, 2003).

Thaumatomyrmex nests have been observed under bark, in rotting wood, under leaves, in abandoned wasp nests (Kempf, 1975; Brandão et al., 1991; Delabie et al., 2000) and one was found in a snail shell lined with hairs scrapped from prey. Jahyny et al. (2002) studied the reproductive system of two species, T. atrox and T. contumax, and found that they reproduce via gamergates and that their colonies are exceptionally small (fewer than five workers, on average, and never more than nine). Kempf (1975) also reported a small colony size for Thaumatomyrmex mutilatus and the existence of an alate queen of T. zeteki (= Thaumatomyrmex atrox). Delabie et al. (2000) documented aggressive interactions between a putative gamergate and her nestmates in a colony of Thaumatomyrmex contumax.

Baroni Urbani and de Andrade (2003), studying the Cuban species: Do the four Cuban Thaumatomyrmex species represent a case of explosive insular speciation? The genus, in Cuba, has a density of ca. one species per 27 km2. In the remaining 20.3 million km2 of the Neotropical region this density falls to roughly one species per 2.5 million km2 (Kempf's 1975 classification) or to one species per 3.8 million km2 (Longino's 1998 classification). These figures need no statistical treatment to convince about the difference between the Cuban and the remaining Neotropical fauna.

D’Esquivel et al (2017) - Small to median ants inhabiting a range of environments, such as tropical wet or dry forests, savannas and semi-arid regions with xerophytic vegetation, being collected up to 2000m altitude. Their colonies, the smallest for population size in the Formicidae family, with about 3-4 individuals for some species, live in natural cavities in the soil, the leaf-litter or the tree trunks (Delabie et al., 2000; Jahyny, unpub. data). They are specialist-predator feeding on polyxenid millipedes (Diplopoda: Penicillata) (Brandão et al., 1991; Jahyny et al., 2008; Rabeling et al. 2012).

Castes

Gamergates reproduce in several species (Jahyny et al., 2002), and they coexist with flying queens in T. ferox.

Nomenclature

The following information is derived from Barry Bolton's New General Catalogue, a catalogue of the world's ants.

  • THAUMATOMYRMEX [Ponerinae: Ponerini]
    • Thaumatomyrmex Mayr, 1887: 530. Type-species: Thaumatomyrmex mutilatus, by monotypy.

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

Description

Schmidt and Shattuck (2014):

Worker

Small (TL 3.3–5.0 mm; Kempf, 1975) ants with the standard characters of Ponerini except that the antennal sockets are very widely separated by a broad posterior extension of the clypeus. Mandibles pitchfork-like with three very long and attenuated teeth, the mandibular articulations located on narrow anterolateral projections of the head. Clypeus generally greatly reduced except for a broad posterior extension. Frontal lobes of moderate size, semi-vertical, reaching or surpassing the anterior clypeal margin. Eyes large and very convex, located anterior of head midline. Metanotal groove absent to shallowly impressed. Propodeal dorsum moderately narrowed but rounded. Propodeal spiracles round. Metapleural gland orifice with a U-shaped cuticular flange posteriorly and a shallow groove laterally. Metatibial spur formula (1p). Petiole ranging from a thick broad scale with sharp lateral margins to a cuboidal node. Gaster with only a weak constriction between pre- and postsclerites of A4. Pretergite of A4 with a distinct stridulitrum. Head and body with variable sculpturing, ranging from smooth and shiny to finely shagreened to finely punctate and rugulose. Head and body with scattered pilosity and no pubescence. Color black.

Queen

Winged queens exist in Thaumatomyrmex ferox (Vasquez et al. 2010).

Male

See description by Kempf (1975).

Larva

Discussed in Kempf (1975) and described for Thaumatomyrmex mutilatus by Kempf (1954) and Wheeler & Wheeler (1964).

References

  • Ashmead, W. H. 1905c. A skeleton of a new arrangement of the families, subfamilies, tribes and genera of the ants, or the superfamily Formicoidea. Can. Entomol. 37: 381-384 (page 382, Thaumatomyrmex in Pachycondylinae, Cylindromyrmicini)
  • Bolton, B. 1994. Identification guide to the ant genera of the world. Cambridge, Mass.: Harvard University Press, 222 pp. (page 164, Thaumatomyrmex in Ponerinae, Thaumatomyrmecini)
  • Bolton, B. 2003. Synopsis and Classification of Formicidae. Mem. Am. Entomol. Inst. 71: 370pp (page 171, Thaumatomyrmex in Ponerinae, Thaumatomyrmecini)
  • Brandão, C. R. F.; Diniz, J. L. M.; Tomotake, E. M. 1991. Thaumatomyrmex strips millipedes for prey: a novel predatory behaviour in ants, and the first case of sympatry in the genus (Hymenoptera: Formicidae). Insectes Soc. 38: 335-344 PDF
  • Dalla Torre, K. W. von. 1893. Catalogus Hymenopterorum hucusque descriptorum systematicus et synonymicus. Vol. 7. Formicidae (Heterogyna). Leipzig: W. Engelmann, 289 pp. (page 46, Thaumatomyrmex in Ponerinae)
  • Delabie, J.H.C., Fresneau, D. and Pezon, A. 2000. Notes on the ecology of Thaumatomyrmex spp. (Hymenoptera: Formicidae: Ponerinae) in southeast Bahia, Brazil. Sociobiology. 36:571-584.
  • Dlussky, G. M.; Fedoseeva, E. B. 1988. Origin and early stages of evolution in ants. Pp. 70-144 in: Ponomarenko, A. G. (ed.) Cretaceous biocenotic crisis and insect evolution. Moskva: Nauka, 232 pp. (page 78, Thaumatomyrmex in Ponerinae, Thaumatomyrmecini )
  • Donisthorpe, H. 1943h. A list of the type-species of the genera and subgenera of the Formicidae. [concl.]. Ann. Mag. Nat. Hist. 11(10): 721-737 (page 732, Thaumatomyrmex in Ponerinae, Thaumatomyrmecini )
  • Emery, C. 1895l. Die Gattung Dorylus Fab. und die systematische Eintheilung der Formiciden. Zool. Jahrb. Abt. Syst. Geogr. Biol. Tiere 8: 685-778 (page 767, Thaumatomyrmex in Ponerinae, Ectatommini)
  • Emery, C. 1901b. Notes sur les sous-familles des Dorylines et Ponérines (Famille des Formicides). Ann. Soc. Entomol. Belg. 45: 32-54 (page 36, Thaumatomyrmex in Ponerinae, Thaumatomyrmecini [Thaumatomyrmii])
  • Emery, C. 1911e. Hymenoptera. Fam. Formicidae. Subfam. Ponerinae. Genera Insectorum 118: 1-125 (page 48, Thaumatomyrmex in Ponerinae, Thaumatomyrmecini)
  • Forel, A. 1895b. A fauna das formigas do Brazil. Bol. Mus. Para. Hist. Nat. Ethnogr. 1: 89-139 (page 111, Thaumatomyrmex in Ponerinae, Ponerini)
  • Forel, A. 1917. Cadre synoptique actuel de la faune universelle des fourmis. Bull. Soc. Vaudoise Sci. Nat. 51: 229-253 (page 236, Thaumatomyrmex in Ponerinae, Thaumatomyrmecini )
  • Hölldobler, B.; Wilson, E. O. 1990. The ants. Cambridge, Mass.: Harvard University Press, xii + 732 pp. (page 10, Thaumatomyrmex in Ponerinae, Thaumatomyrmecini)
  • Jaffe, K. 1993. El mundo de las hormigas. Baruta, Venezuela: Equinoccio (Ediciones de la Universidad Simón Bolívar), 188 pp. (page 8, Thaumatomyrmex in Ponerinae, Ponerini)
  • Jahyny B., Delabie J., Fresneau D. 2002. Mini-sociétés sans reine chez le genre néotropical Thaumatomyrmex Mayr, 1887 (Formicidae : Ponerinae). Actes des Colloques Insectes Sociaux, 15: 33-37.
  • Jahyny, B., Lacau, S., Delabie, J. H. C. & Fresnau, D. 2008. Le genre Thaumatomyrmex Mayr 1887, cryptique et prédateur spécialiste de Diplopoda Penicillata. pp. 329-346 in Sistemática, biogeografía y conservación de las hormigas cazadoras de Colombia, Editors Jiménez, E., Fernández, F., Arias, T. M. & Lozano-Zambrano, F. H. Instituto de Investigación de Recursos Biológicos Alexander von Humboldt, Bogotá, Colombie. 609p.
  • Kempf, W. W. 1972b. Catálogo abreviado das formigas da regia~o Neotropical. Stud. Entomol. 15: 3-344 (page 250, Thaumatomyrmex in Ponerinae, Ponerini)
  • Kempf, W. W. 1975b. A revision of the Neotropical ponerine ant genus Thaumatomyrmex Mayr (Hymenoptera: Formicidae). Stud. Entomol. 18: 95-126 (page 95, Thaumatomyrmex in Ponerinae, Ponerini)
  • 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.) Advances in myrmecology. Leiden: E. J. Brill, xxvii + 551 pp. (page 35, Revison of genus)
  • Mayr, G. 1887. Südamerikanische Formiciden. Verh. K-K. Zool.-Bot. Ges. Wien 37: 511-632 (page 530, Thaumatomyrmex as genus)
  • Schmidt, C.A. & Shattuck, S.O. 2014. The higher classification of the ant subfamily Ponerinae (Hymenoptera: Formicidae), with a review of ponerine ecology and behavior. Zootaxa. 3817, 1–242 (doi:10.11646/zootaxa.3817.1.1)
  • Smith, M. R. 1944b. Ants of the genus Thaumatomyrmex Mayr with the description of a new Panamanian species (Hymenoptera: Formicidae). Proc. Entomol. Soc. Wash. 46: 97-99 (page 97, Key to species (out of date))
  • Weber, N. A. 1942c. The genus Thaumatomyrmex Mayr with description of a Venezuelan species (Hym.: Formicidae). Bol. Entomol. Venez. 1: 65-71 (page 65, Key to species (out of date))
  • Wheeler, W. M. 1910b. Ants: their structure, development and behavior. New York: Columbia University Press, xxv + 663 pp. (page 135, Thaumatomyrmex in Ponerinae, Ectatommini)
  • Wheeler, W. M. 1922i. Ants of the American Museum Congo expedition. A contribution to the myrmecology of Africa. VII. Keys to the genera and subgenera of ants. Bull. Am. Mus. Nat. Hist. 45: 631-710 (page 644, Thaumatomyrmex in Ponerinae, Thaumatomyrmecini )