Acropyga silvestrii

Lapolla (2004) - Even though the species is found in savanna type habitat in many places across its range, A. silvestrii apparently does not overlap with Acropyga arnoldi, which is found exclusively in southern Africa.

Identification
From Lapolla (2004):

Diagnosis - Worker: Antennae 11-10 segmented; head distinctly longer than broad; head width not greater than 0.5 mm; in lateral view pronotum with short shelf; mesosomal dorsum flat, with appressed hairs. Queen: unknown. Male: unknown. Compare with Acropyga arnoldi and Acropyga paleartica.

This species can be easily separated from Acropyga arnoldi by its size (A. silvestrii TL: 1.6-2.1; HW: 0.383-0.454 versus A. arnoldi TL: 2.1-2.4; HW: 0.517-0.619). Differentiation from Acropyga paleartica can be slightly more difficult, though the torulae of A. silvestrii are very closely set together (almost touching medially) and their mandibles do not have offset basal teeth.

The relationship of this species to A. arnoldi is unclear since males remain unknown. A. silvestrii is observed with up to 7 teeth, but has not been observed with at least a 4-segmented maxillary palp as in A. arnoldi and A. paleartica.

Distribution based on Regional Taxon Lists
Afrotropical Region: Eritrea, Ghana, Kenya, Rwanda, Tanzania, Togo, Uganda. Palaearctic Region: Ethiopia.

From LaPolla (2004): The distribution of A. silvestrii stretches from western Africa as far south and east as northern Tanzania. This is the only Acropyga known from the rainforests of Africa, which is interesting because in other areas where rainforests are found the diversity of Acropyga is substantially higher. The low species diversity found in Africa may be an artifact of collecting since there are few collections from Africa (particularly West Africa) available for study, or may indicate something of biological interest.

Habitat
The species is found in a variety of habitats from tropical savannas to rainforests; it has also been collected from cacao plantations. It has been recorded from elevations up to 1600 m.

Nomenclature

 *  silvestrii. Acropyga silvestrii Emery, 1915g: 21, fig. 11 (w.) ETHIOPIA. Combination in Acropyga (Malacomyrma): Emery, 1922d: 109. See also: LaPolla, 2004a: 78.

Worker
From LaPolla (2004) - Head: yellow to slightly brownish yellow; covered in dense layer of appressed hairs; head distinctly longer than broad; posterior margin entire; 11-10 segmented, incrassate antennae; apical segment about as long as proceeding 3 segments; scape fails to reach posterior margin by about length of pedicel; clypeus medially slightly convex, with several erect hairs; mandible with 4-7 uneven teeth; inner mandibular margin nearly parallel with anterior clypeal margin. Mesosoma: yellow; pronotum in lateral with a short shelf, then rising steeply toward mesonotum; mesonotum flat, covered in layer of appressed to suberect hairs; metanotal area often distinct; propodeum at about same height as mesonotum, rounded toward a steep declivity. Gaster: petiole thick and erect, rounded at apex; gaster yellow; covered in a thick layer of appressed hairs, with suberect to erect hairs scattered throughout.

Measurements Worker (n= 10): TL: 1.16-2.15; HW: 0.383-0.454; HL: 0.429-0.506; SL: 0.297- 0.349; ML: 0.425-0.567; GL: 0.64-1.16; CI: 84.0-95.18; SI: 72.12-82.2.

Queen
Queens are not known for this species.

Male
Males are not known for this species.

Type Material
Acropyga silvestrii Emery, 1915: 21. 5 syntype workers, ERITREA: Ghinda (MNHG) [1 worker examined]. The designated lectotype is a worker labeled JSL TYPE # 125 and is deposited at MHNG. Emery, 1922: 109, combination in subgenus Malacomyrma.

Additional 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., 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, 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.