| Acropyga parvidens|
(Wheeler, W.M. & Mann, 1914)
LaPolla (2004): Acropyga parvidens appears to be endemic to Hispaniola, having been found in leaf litter in both Haiti and the Dominican Republic. Weber (1944) reported Acropyga parvidens was found associated with (unidentified) mealybugs. No males are known for Acropyga parvidens and the only other species of this genus known from Hispaniola is Acropyga dubitata. It is only known from males. It is possible these two species are actually one.
LaPolla (2004): Worker: 9-11 segmented antennae; mandible with 4 prominent teeth; mesonotum much higher than propodeum, with a layer of appressed hairs at apex. Queen: As in worker with modification expected for caste.
Keys including this Species
Distribution based on Regional Taxon Lists
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Distribution based on specimens
Little is known about Acropyga parvidens. 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.
The males are unknown.
The following information is derived from Barry Bolton's New General Catalogue, a catalogue of the world's ants.
- parvidens. Rhizomyrma parvidens Wheeler, W.M. & Mann, 1914: 46 (w.) HAITI. Combination in Acropyga (Rhizomyrma): Emery, 1925b: 30. Senior synonym of mesonotalis: LaPolla, 2004a: 56.
- mesonotalis. Acropyga (Rhizomyrma) mesonotalis Weber, 1944: 111, fig. 13 (w.q.) HAITI. Junior synonym of parvidens: LaPolla, 2004a: 56.
Unless otherwise noted the text for the remainder of this section is reported from the publication that includes the original description.
Length 1.8-2 mm.
Head subrectangular, a little broader than long, as broad in front as behind, with straight sides and a slight angular excision in the middle of the posterior border. Eyes minute, consisting of about 4 small ommatidia, situated at the anterior third of the head. Mandibles oblique but with distinct basal and apical borders, the latter with 4 small sub equal teeth, much smaller than in any of the known species of the genus. Clypeus short and convex, with the anterior border entire, straight and transverse in the middle. Frontal area distinct, triangular; frontal and occipital grooves distinct. Antennae 10-jointed; scapes reaching to the posterior corners of the head; first funicular joint longer than broad, second joint small, as long as broad; joints 3-5 much broader than long, joints 7-8 as long as broad, terminal joint as long as the 3 preceding joints together. Thorax shaped much as in Acropyga goeldii, but shorter and stouter, at least behind, where it is as broad as in front; seen from above the sides are rather concave in the middle; pronotum much broader than long, with less convex humeri than in goeldii, mesonotum not longer than broad, as it is in goeldii, fitting into the semicircular excavation of the posterior portion of the pronotum, convex and rising above the latter in profile, abruptly sloping behind to the mesoepinotal constriction which is pronounced but very short. Epinotum distinctly broader than long, in profile lower than the mesonotum, with rather straight base and declivity meeting at a rounded, obtuse angle, the base. distinctly longer than the declivity. Petiole with an erect, well-developed scale, which is a little more than half as broad as the epinotum, but not as high, compressed anteroposteriorly, with flattened anterior and posterior surfaces and rather blunt, entire, broadly rounded superior border. Gaster rather large, elliptical. Legs stout.
Body shining, finely shagreened and sparsely punctate. Mandibles and clypeus somewhat more opaque.
Hairs and pubescence whitish or pale yellow, the former rather long, unequal, erect and confined to the body, the latter rather dense and short, covering both body and appendages, but not obscuring the shining surface.
Pale brownish yellow throughout; legs and antennae a little paler, head in some specimens a little darker, only the eyes and mandibular teeth brown.
Measurements (La Polla 2004) (n=4): TL: 1.99-2.19; HW: 0.496-0.55 1; HL: 0.489-0.54; SL: 0.339-0.408; ML: 0.527-0.589; GL: 0.941-l.09; CI: 98.61-104.7; SI: 66.21-74.05.
LaPolla (2004): As in worker with modification expected for caste and with the following differences: mesosomal dorsum covered in thick layer of appressed hairs, with scattered erect hairs; longest mesosomal hairs typically on scutellum.
Measurements (n=3): TL:2.83-2.87; HW: 0.576-0.597; HL: 0.55-0.591 ; SL: 0.431-0.495; ML: 0.841-0.915; GL: 1.34-l.48; CI: 100.85-104.73; SI: 74.83-82.9l.
Haiti. Described from three workers, two taken at Petionville and one at Diquini.
- 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 56, senior synonym of mesonotalis)
- 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.
- Prins, A.J. 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.
- Wheeler, W. M.; Mann, W. M. 1914. The ants of Haiti. Bull. Am. Mus. Nat. Hist. 33: 1-61 (page 46, worker described)
- 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.