Daceton armigerum

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Daceton armigerum
Scientific classification
Kingdom: Animalia
Phylum: Arthropoda
Class: Insecta
Order: Hymenoptera
Family: Formicidae
Subfamily: Myrmicinae
Tribe: Attini
Genus: Daceton
Species: D. armigerum
Binomial name
Daceton armigerum
(Latreille, 1802)

Daceton armigerum casent0178489 profile 1.jpg

Daceton armigerum casent0178489 dorsal 1.jpg

Specimen labels

Synonyms

Daceton armigerum has been studied extensively by Wheeler & Wheeler (1954, description of larvae), Wilson (1962, ecology and behavior), Blum & Portocarrero (1966, trail pheromone and venom), Hölldobler et al. (1990, chemical communication), Moffet & Tobin (1991, physical castes), Groenenberg (1996, mandibular mode of action), and Bolton (1999, 2000, classification).

Photo Gallery

  • Daceton armigerum infected by Ophiocordyceps dacetini. (Photo by João P. M. Araújo)

Identification

Key to the two Daceton species.

Pronotal humeral spines bifurcate, the anterior tip larger than the posterior one. First gastral tergite without standing hairs (sometimes with very short, appressed hairs). Mesonotum and metanotum divided by a strongly impressed metanotal groove. Inner (masticatory) margin of mandibles with a row of short think setae . . . . . Daceton armigerum

Pronotal humeral spines long and simple. First gastral tergite with suberect to subdecumbent hairs. Mesonotum and metanotum divided by a weakly impressed metanotal groove. Inner (masticatory) margin of mandibles lacking a row of short thick setae . . . . . Daceton boltoni

Keys including this Species

Distribution

Bolivia, Brazil, Colombia, Ecuador, French Guiana, Guyana, Peru, Suriname, Trinidad and Venezuela.

Distribution based on Regional Taxon Lists

Neotropical Region: Bolivia, Brazil (type locality), Ecuador, French Guiana, Guyana, Peru, Suriname, Trinidad and Tobago, Venezuela.

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Habitat

Terra Firma and flooded forests.

Biology

Daceton armigerum Copyright: Piotr Naskrecki

Azorsa & Sosa (2008) - Typically nests in cavities in the branches and trunks of trees previously bored by beetles and other insects. Blum and Portocarrero (1966) and Moffet and Tobin (1991) state that colonies of D. armigerum contain up to 2500 individuals, whereas Wilson (1962) and Hölldobler & Wilson (1990) estimate that colonies contain between 5000 to 10000 workers. Daceton armigerum has a complex continuously polymorphic caste system, in which smaller workers nurse the brood and larger workers hunt, dismember prey items, and defend the nest (Wilson 1962; Oster & Wilson 1978; Hölldobler & Wilson 1990). Wilson (1962) reports that workers of this highly predaceous myrmicine ant hunt individually for a variety of live insects, including flies, grasshoppers, larvae and adults of moths and beetles, and fulgorids. In addition, some workers have been observed tending coccids (Bodkin in Crawley 1916; Brown & Wilson 1960; Wilson 1962). (Refer to Wilson [1962] for further information on the behavior of D. armigerum.) Recently, Yanoviak et al. (2005) found that individuals of D. armigerum show controlled aerial descent behavior. The genus has been considered primitive with respect to other members of the Dacetini (Brown and Wilson 1959; Bolton 1998, 1999, 2000), but a phylogenetic analysis of the tribe is necessary to fully understand the relationships of its constituent species and genera. Current molecular phylogenetic evidence suggests that Dacetini may not be monophyletic (Brady et al. 2006).

Fungi

This species is a host for the fungus Ophiocordyceps dacetini (Araujo et al., 2018).

Castes

Male

Nomenclature

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

  • armigerum. Formica armigera Latreille, 1802c: 244, pl. 9, fig. 58 (w.) BRAZIL. Smith, F. 1853: 226 (q.m.); Wheeler, G.C. & Wheeler, J. 1955a: 122 (l.). Combination in Daceton: Perty, 1833: 136. Senior synonym of cordata: Roger, 1862c: 290. See also: Wilson, 1962b: 401; Bolton, 2000: 18; Azorsa & Sosa-Calvo, 2008: 30.
  • cordata. Myrmecia cordata Fabricius, 1804: 425 (w.) CENTRAL AMERICA. Junior synonym of armigerum: Roger, 1862c: 290.

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

Description

Worker

Azorsa & Sosa (2008) - Measurements (mm): EL 0.44–0.87, GL 1.89–4.50, HL 1.44–4.06, HW 1.58–4.17, ML 0.79–3.32, PL 0.78–1.93, PPL 0.26-0.51, PSL 0.32-1.59, PW 1.38-4.60, SL 0.94-2.77, TL 6.91-17.8, WL 1.70–4.24.

Indexes: CI 102–113, MI 55–88, PI 41–52, PSI 18–39, SI 59–73 (17 measured).

Polymorphic. Head wider than long, heart-shaped. Mandibles linear and elongate, each with an apical fork of two teeth that overlap at full closure, of which the ventral tooth is the largest. Inner (masticatory) margin of mandibles lacking any dentition but with a series of short, thick setae that differ from any other pilosity present on mandibles. Outer margin of mandibles lacking hairs completely or with very short, appressed hairs. Mandibles, in full-face view, somewhat long and narrow [(MW/ML')*100= 25–40]. Palp formula 5,3. Depressions, adjacent to and ventral to the mandibular insertion, deep. Clypeus without standing hairs. Pronotal humeri with acute tubercles. Lateral pronotal spines bifurcate, the anterior tips larger than the posterior ones. Metanotal groove deeply impressed. Mesosoma glabrous. Petiolar node with an anterior-lateral pair of long spines and a pair of small but sharp tubercles, located underneath the anterior-lateral spines. First gastral tergite finely reticulate and devoid of any erect or semi-erect pilosity, sometimes with very short, appressed hairs. Color of head, mesosoma, and metasoma, usually red-brown to red-yellowish, sometimes dark red-brown or rarely bicolored; petiole, postpetiole, and gaster darker than rest of body.

Most of the within-species morphological variation in D. armigerum workers is manifested in the form of the promesonotum and, to a lesser degree, in the forms of the petiole, postpetiole, and gaster. This variation includes: (i) Lateral spines bifurcate, the posterior spine projecting upwards and curving at the tip in major workers, whereas in small or median workers this spine not curving at the tip. In small workers the posterior spine is very short, almost vestigial when viewed in profile, but conspicuous in dorsal view. (ii) Short, simple, and appressed hairs present on the first gastral tergite in some individuals from Brazil and Peru. On other workers, hairs on the first gastral segment are absent. (iii) Humeral spines, in smaller workers, vestigial or present as very low carinae. Median and larger-sized workers with humeral tubercles that are spinose or acute. (iv) The posterior pair of petiolar tubercles reduced, rounded and low in smaller workers, whereas tubercles acute in larger workers. (v) Large workers with posterior promesonotal tubercles truncate and flattened in profile. (vi) Anterior spines of petiole long and diverging with intervening space concave or with intervening space discontinuous. Anterior spines of petiole in smaller workers shorter than in other castes.

Type Material

Azorsa & Sosa (2008): Syntype(?) worker, Brazil (not seen).

Myrmecia cordata. Syntypes, 2 workers, America Meridionali [South America]. (seen)

Myrmecia cordata Fabricius, Syntypes, 2 workers, labeled: “Essequibo [possibly Guyana], Smidt. Mus. de Sehestedt. Armigerum, Latr. [Latreille] Myrmecia cordata, worker, Fabr. [Fabricius].” Deposited in Zoologisk Museum, University of Copenhagen.

References

  • Araújo, J.P.M., Evans, H.C., Kepler, R., Hughes, D.P. 2018. Zombie-ant fungi across continents: 15 new species and new combinations within Ophiocordyceps. I. Myrmecophilous hirsutelloid species. Studies in Mycology 90: 119–160 (DOI 10.1016/j.simyco.2017.12.002).
  • Blum, M. S.; Portocarrero, C. A. 1964. Chemical releasers of social behavior - IV. The hindgut as the source of the odor trail pheromone in the Neotropical army ant genus Eciton. Ann. Entomol. Soc. Am. 57: 793-794 (behavior)
  • Bolton, B. 1995b. A new general catalogue of the ants of the world. Cambridge, Mass.: Harvard University Press, 504 pp. (page 168, catalogue)
  • Bolton, B. 1999. Ant genera of the tribe Dacetonini (Hymenoptera: Formicidae). J. Nat. Hist. 3 33: 1639-1689 (page 1655, see also)
  • Brown, W. L., Jr. 1988h. Data on Malpighian tubule numbers in ants (Hymenoptera: Formicidae). Pp. 17-27 in: Trager, J. C. (ed.) Advances in myrmecology. Leiden: E. J. Brill, xxvii + 551 pp. (page 23, anatomy)
  • Fernández, F.; Palacio, E. E.; MacKay, W. P.; MacKay, E. S. 1996. Introducción al estudio de las hormigas (Hymenoptera: Formicidae) de Colombia. Pp. 349-412 in: Andrade, M. G., Amat García, G., Fernández, F. (eds.) Insectos de Colombia. Estudios escogido (page 381, anatomy)
  • Gronenberg, W. 1996. The trap-jaw mechanism in the dacetine ants Daceton armigerum and Strumigenys sp. J. Exp. Biol. 1 199: 2021-2033 (page 2021, anatomy)
  • Hölldobler, B.; Palmer, J. M.; Moffett, M. W. 1990. Chemical communication in the dacetine ant Daceton armigerum (Hymenoptera: Formicidae). J. Chem. Ecol. 1 16: 1207-1219 (biology)
  • Kempf, W. W. 1961b. A survey of the ants of the soil fauna in Surinam (Hymenoptera: Formicidae). Stud. Entomol. 4: 481-524 (page 514, behavior)
  • Kempf, W. W. 1972b. Catálogo abreviado das formigas da regia~o Neotropical. Stud. Entomol. 15: 3-344 (page 95, catalogue)
  • Latreille, P. A. 1802b. Histoire naturelle générale et particulière des Crustacés et des insectes. Tome 3. Familles naturelles des genres. Paris: F. Dufart, xii + 467 pp. (page 244, pl. 9, fig. 58 worker described)
  • Perty, M. 1833. Delectus animalium articulatorum, quae in itinere per Brasiliam annis MDCCCXVII-MDCCCXX jussu et auspiciis Maximiliani Josephi I. Bavariae regis augustissimi peracto, collegerunt Dr. J. B. Spix et Dr. C. F. Ph. de Martius. Fasc. 3. Monach (page 136, Combination in Daceton)
  • Roger, J. 1862c. Synonymische Bemerkungen. 1. Ueber Formiciden. Berl. Entomol. Z. 6: 283-297 (page 290, senior synonym of cordata)
  • Smith, F. 1853 [1854]. Monograph of the genus Cryptocerus, belonging to the group Cryptoceridae - family Myrmicidae - division Hymenoptera Heterogyna. Trans. Entomol. Soc. Lond. (2) 2: 213-228 (page 226, queen, male described)
  • Wheeler, G. C.; Wheeler, J. 1955a [1954]. The ant larvae of the myrmicine tribes Basicerotini and Dacetini. Psyche (Camb.) 61: 111-145 (page 122, larva described)
  • Wheeler, G. C.; Wheeler, J. 1973c. The ant larvae of the tribes Basicerotini and Dacetini: second supplement (Hymenoptera: Formicidae: Myrmicinae). Pan-Pac. Entomol. 49: 207-214 (page 211, larva described)
  • Wilson, E. O. 1962b. Behavior of Daceton armigerum (Latreille), with a classification of self-grooming movements in ants. Bull. Mus. Comp. Zool. 127: 403-421 (page 401, behavior)