Acropyga dubia

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Acropyga dubia
Scientific classification
Kingdom: Animalia
Phylum: Arthropoda
Class: Insecta
Order: Hymenoptera
Family: Formicidae
Subfamily: Formicinae
Tribe: Plagiolepidini
Genus: Acropyga
Species: A. dubia
Binomial name
Acropyga dubia
Karavaiev, 1933

Acropyga dubia casent0906271 p 1 high.jpg

Acropyga dubia casent0906271 d 1 high.jpg

Specimen Labels

Nothing is known about the biology of this species.

Identification

LaPolla (2004) - Worker: 11 segmented antennae; mandible with 6 teeth; head slightly longer than broad; dorsum with dense layer of appressed hairs, with occasional scattered erect hairs. Queen: as in worker with modifications expected for caste. Male: unknown. Compare with Acropyga myops.

This species has workers that are morphologically similar to Acropyga myops, but differ primarily in possessing a narrower head (< 0.6 mm in A. dubia versus > 0.6 mm in A. myops), and in geographical distribution (A. dubia has not been found in Australia, the only known location for A. myops).

Keys including this Species

Distribution

Distribution based on Regional Taxon Lists

Indo-Australian Region: Borneo, Indonesia (type locality), Malaysia.

LaPolla (2004): I have only examined specimens of this species from Malaysian Borneo, though the original description reports the syntypes as being from Sumatra.

Check distribution from AntMaps.

Distribution based on specimens

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The above specimen data are provided by AntWeb. Please see Acropyga dubia for further details

Biology

Little is known about Acropyga dubia. Until further studies reveal more about this species we can infer that its natural history and biology should be similar to other Acropyga. LaPolla published a worldwide revision of the Acropyga in 2004 and the following synopsis is based on this excellent treatment of the genus.

In overall appearance Acropyga are small, robust, yellowish ants possessing a thin, easily collapsible cuticle. The species generally appear rather similar to each other morphologically. In some species workers and queens display an unusual range of phenotypic variation. Antennal segment number, for example, can vary within and between species. Even a single specimen may posses antennae with a different number of antennal segments and workers in numerous species possess one more antennal segment than conspecific males.

The small eyes, reduced antennae segmentation, lightly pigmented cuticle, and hairs covering the cuticle of Acropyga species are suggestive of a completely subterranean existence. Species also display photophobic behavior (Weber, 1944; LaPolla et al., 2002). Acropyga can survive in a wide range of habitats, from deserts to rainforests, though they do not seem able to survive in regions where temperatures below freezing persist for several months at a time. Some species, such as Acropyga pallida and Acropyga silvestrii for example, are found within a very wide range of habitats. Undoubtedly, the Acropyga lifestyle of existing below the surface buffers them against extremes of the outside environment.

Acropyga nests are found in leaf litter, under stones, in rotten wood (lying on or near the soil surface) and in the soil. Observations of nests of various species show the nests are large, consisting of at least several thousand individuals. The nest structure is diffuse with apparently no central nesting location (LaPolla et al., 2002). Tunnels and indistinct chambers stretch out over large areas through the nesting medium. Polygyny has been suggested for several species. The origins of polygyny remains uncertain, but two routes are suggested based on field observations. Biinzli (1935) found both the occurrence of pleometrosis (founding of a colony by multiple queens) and the acquisition of young queens by established colonies in Acropyga exsanguis.

All Acropyga are thought to be hypogaeic (living entirely underground), surviving primarily by "tending" mealybugs (Hemiptera: Pseudococcidae) on underground roots for their exudate (sometimes referred to as "honeydew") (Weber, 1944; Williams, 1998). This mutually beneficial relationship is called trophobiosis (Holldobler and Wilson, 1990).

Acropyga species are all believed to be obligate coccidophiles (dependent on their tended mealybugs for survival). The strength of this trophophitic relationship is clarified by a number of observations. Queens of eleven species have been observed emerging from their nests prior to their mating flight with a mealybug held in their mandibles (Biinzli, 1935; Wheeler, 1935b; Brown, 1945; Eberhard, 1978; Prins, 1982; Buschinger et al., 1987; Williams, 1998; Johnson et al., 2001). The mealybug that each queen carries presumably serves as a "seed individual" from which a new generation of mealybugs will be started in the newly founded ant colony (Weber, 1944; Williams, 1998). This behavior is called trophophoresy (LaPolla et al. 2002) with queens exhibiting this behavior said to be trophophoretic. The mealybugs utilized by Acropyga belong to the subfamily Rhizoecinae, and it is likely that the mealybugs are not able to survive independently of the ants (Williams, 1998). LaPolla et al. (2002) observed that Acropyga epedana keeps mealybugs with their brood. When a nest in captivity was starved, workers refused a variety of food items presented to them, suggestiving that the ants are completely dependent on the mealybugs as a food source. Fossil evidence suggests that the trophobiotic behavior ofAcropyga ants is an ancient one. Johnson et al. (2001) reported that Acropyga queens were discovered in Dominican amber, either holding a mealybug or with a mealybug nearby in the amber matrix. The amber was dated to the Miocene and is at least 15-20 million years old.

Castes

Males are not known for this species.

Nomenclature

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

  • dubia. Acropyga (Rhizomyrma) dubia Karavaiev, 1933a: 311, fig. 3 (w.m.) INDONESIA (Sumatra). LaPolla, 2004a: 61 (q.).

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

Description

Worker

LaPolla (2004) - (n=8): TL: 1.79-2.15; HW: 0.485-0.55; HL: 0.499-0.585; SL: 0.399-0.447; ML: 0.538-0.611; GL: 0.623-0.957; CI: 89.91-97.21; SI: 79.89-81.81.

Head: yellow; head slightly longer than broad; posterior margin entire to slightly concave medially; 11 segmented, incrassate antennae; scape reaches or nearly reaches (approximately 1/3 length of pedicel) posterior margin; clypeus convex medially, with appressed to erect hairs on surface; mandible broad with 6 teeth; 3rd tooth from apical smaller than others; basal tooth sometimes smaller than others and set back further than other teeth on masticatory margin; dorsal surface of mandible covered in a thick layer of short erect hairs (approximately 25 hairs); inner mandibular margin and anterior clypeal margin nearly parallel with each other. Mesosoma: yellow; in lateral view pronotum rises steeply toward mesonotum; pronotum covered in layer of appressed hairs, with scattered erect hairs posteriorly; mesonotum rounded, covered in layer of appressed hairs; scattered erect hairs throughout; metanotal area distinct; propodeum rounded, covered in layer of appressed hairs; declivity steep. Gaster: petiole thick and erect, reaching height of upper portion of propodeal spiracle; gaster yellow; covered in a thick layer of appressed hairs, with scattered erect hairs throughout.

Queen

LaPolla (2004) - (n=1): TL: 3.06; HW: 0.663; HL: 0.6; SL: 0.606; ML: 1.1; GL: 1.36; CI: 110.5; SI: 91.40. As in worker with modifications expected for caste and with the following differences: overall color brownish-yellow, darker toward apex of head and on gaster dorsum.

Type Material

LaPolla (2004) - Acropyga dubia Karavaiev, 1933: 311 (w.m.). 3 syntype workers, 1 syntype male, INDONESIA: Sumatra (O. John) (depository unknown) [not examined]. The syntypes of this species could not located for examination. The original description includes description of a male, but because the syntypes could not be located and no other male specimens have been found in collections, the male unfortunately cannot be described at this time.

References

  • Biinzli, G.H. 1935. Untersuchungen iiber coccidophile Ameisen aus den Kaffeefelden von Surinam. Mitteilungen der Schweizerischen Entomologischen Gesellschaft 16:455-593.
  • Brown, W.L., Jr. 1945. An unusual behavior pattern observed in a Szechuanese ant. Journal of the West China Border Research Society 15:185-186.
  • Buschinger, J., J. Heinze & K. Jessen. 1987. First European record ofa queen ant carrying a mealybug during her mating flight. NatUlwissenschaften 74:139-140.
  • Eberhard, W.G. 1978. Mating swarms ofa South American Acropygia [sic.] (Hymenoptera: Formicidae). Entomological News 89(1 & 2):14-16.
  • Eisner, T. 1957. A comparative morphological study ofthc proventriculus of ants (Hymenoptera: Formicidae). Bulletin ofthe Museum of Comparative Zoology 116:439-490.
  • Holldobler B . & E.O. Wilson. 1990. The Ants. Belknap Press, Cambridge, Massachusetts, 732 pp.
  • Johnson, c., D. Agosti, J.H. Delabie, K. Dumpert, OJ. Williams, M. von Tschimhaus & U. Maschwitz. 2001 . Acropyga and Azteca Ants with Scale Insects: 20 Million Years ofIntimate Symbiosis. American Museum Noviates 3335:1-18.
  • LaPolla, J.S. 2004a. Acropyga of the world. Contributions of the American Entomological Institute. 33(3):1-130. PDF (page 61, worker described)
  • LaPolla, J.S., S.P. Cover & U.G. Mueller. 2002. Natural history of the mealybug-tending ant Acropyga epedana, with descriptions of the male and queen castes. Transactions of the American Entomological Society 128(3):367-376.
  • Karavaiev, V. 1933a [1932]. Ameisen aus dem Indo-Australischen Gebiet, VII. Konowia 11: 305-320 (page 311, fig. 3 worker, male described)
  • Prins, AJ. 1982. Review of Anoplolepis with reference to male genitalia, and notes on Acropyga. Annals of the South African Museum 89:215-247.
  • Weber, N.A. 1944. The Neotropical coccid-tending ants of the genus Acropyga Roger. Annals of the Entomological Society of America 37:89-122.
  • Wheeler, G.C. & J.C. Wheeler. 1953. The ant larvae of the subfamily Formicinae. Annals of the Entomological Society of America 46:126-171.
  • Wheeler, W.M. 1935b. Ants of the genus Acropyga Roger, with description ofa new species. Journal of the New York Entomological Society 43:321-329.
  • Williams, D J . 1998. Mealybugs of the genera Eumyrmococcus Silvestri and Xenococcus Silvestri associated with the ant genus Acropyga Roger and a review of the subfamily (Hemiptera, Coccoidea, Pseudoccidae). Bulletin of the British Museum (Natural History)(Entomology) 67:1-64.