Acropyga guianensis

Specimens have been collected from the leaf litter in rainforest but otherwise nothing is known about the biology of Acropyga guianensis.

Identification
LaPolla (2004) - Worker: 10-11 segmented antennae; head distinctly longer than broad; mandible with 4-5 teeth, a distinct diastema between 3rd and 4th tooth; dorsum of mesosoma rounded in lateral view, with a layer of appressed hairs underneath several prominent erect hairs. Queen: as in worker with modifications expected for caste. Male: unknown. Compare with larger species of the goeldii complex, Acropyga ayanganna, and Acropyga decedens.

At first examination it is possible to confuse the worker of A. guianensis with some members of the goeldii complex of species. Upon closer inspection, however, it is fairly easy to distinguish this species with its head longer than broad and a distinctive mandibular dentition: 4 teeth with basal tooth separated by a diastema, or 5 teeth with a small tooth in the diastema region. The mesosoma is useful for identification as well, with mesosomal shape and the placement of dorsal hairs being diagnostic. Additionally, the clypeus is broad and lacks a dense covering of erect hairs, which are commonly observed many goeldii complex species.

Distribution based on Regional Taxon Lists
Neotropical Region: Bolivia, Brazil, Colombia, Ecuador, Guyana.

LaPolla (2004): This species has a large range, having been collected from northern South America south into Bolivia.

Nomenclature

 * . Acropyga (Rhizomyrma) guianensis Weber, 1944: 120, fig. 1 (w.) GUYANA.
 * LaPolla, 2004a: 76 (q.).
 * Status as species: Kempf, 1972a: 17; Bolton, 1995b: 57; LaPolla, 2004a: 75 (redescription); Fernández & Ortiz-Sepúlveda, 2019: 732.

LaPolla (2004) - The lack of a worker-associated male specimen for this species makes its placement within the genus problematic and it therefore remains unplaced in a species-group. Despite its initial appearance to the contrary, I do not think this species belongs in the decedens species-group, for its mandibles, clypeus and mesosomal characters (see above for contrasts) do not suggest placement in that group. The narrow-headed Acropyga stenotes is possibly closely related to A. guianensis based on similar mesosomal characteristics (see A. stenotes discussion section for more details). Once males are discovered for this species a more precise phylogenetic placement will be possible.

Worker
LaPolla (2004) - (n=10): TL: 1.83-2.4; HW: 0.472-0.532; HL: 0.508-0.609; SL: 0.408-0.5; ML: 0.488-0.682; GL: 0.693-1.09; CI: 84.24-95.36; SI: 84.50-96.08.

Head: brownish-yellow; head distinctly longer than broad; covered in appressed hairs; posterior margin entire to slightly concave; suberect to erect hairs often at posterolateral corners; 10-11 segmented, incrassate antennae; scape typically surpasses posterior margin by about the length of the pedicel; clypeus convex medially, surface with numerous long erect hairs; mandible usually with 4 teeth; 4th tooth separated by a short diastema; a smaller tooth can sometimes be found in the diastema region separating the 4th and basal teeth, making the mandible effectively 5-toothed. Mesosoma: brownish-yellow; in lateral view, pronotum rises steeply toward mesonotum; posteriorly pronotum with many long erect hairs; mesonotum with many longer erect hairs and thick layer of appressed hairs underneath; propodeum slightly below layer of mesonotum; mesosomal dorsum rounded from posterior portion of pronotum through the propodeum; declivity steep. Gaster: petiole thick and erect; gaster brownish-yellow; covered with a thick layer of appressed hairs, with many scattered erect hairs throughout, giving gaster a spiky appearance, especially toward posterior end.

Queen
LaPolla (2004) - (n=3): TL: 3.48-3.65; HW: 0.631-0.64; HL: 0.696-0.7; SL: 0.612-0.636; ML: 1.07-1.18; GL: 1.87-1.77; CI: 90.29-91.82; SI: 96.84-100.79.

As in worker except for modifications expected with caste, and with the following differences: overall much darker than worker, becoming brown dorsally in many specimens; mesonotum flat, with abundant suberect to erect hairs and a dense layer of appressed hairs; scutellum with many erect hairs; propodeum low.

Male
Males are not known for this species.

Type Material
Acropyga (Rhizomyrma) guianensis Weber, 1944: 120 (w.). 3 syntype workers, GUYANA: HMPS, Mazaruni River (N.A. Weber) (MCZC) [examined]. The designated lectotype is a worker on the same point as one of the paralectotypes; the lectotype is the specimen raised up slightly off of the point, and is labeled JSL TYPE # 124. The second paralectotype, on another point, has another Acropyga specimen next to it that is clearly not A. guianensis (probably Acropyga smithii), so it is not a paralectotype of this species.

References based on Global Ant Biodiversity Informatics

 * Alonso L. E., J. Persaud, and A. Williams. 2016. Biodiversity assessment survey of the south Rupununi Savannah, Guyana. BAT Survey Report No.1, 306 pages.
 * Fernández, F. and S. Sendoya. 2004. Lista de las hormigas neotropicales. Biota Colombiana Volume 5, Number 1.
 * Fichaux M., B. Bechade, J. Donald, A. Weyna, J. H. C. Delabie, J. Murienne, C. Baraloto, and J. Orivel. 2019. Habitats shape taxonomic and functional composition of Neotropical ant assemblages. Oecologia 189(2): 501-513.
 * Franco W., N. Ladino, J. H. C. Delabie, A. Dejean, J. Orivel, M. Fichaux, S. Groc, M. Leponce, and R. M. Feitosa. 2019. First checklist of the ants (Hymenoptera: Formicidae) of French Guiana. Zootaxa 4674(5): 509-543.
 * Johnson C., D. Agosti, J. H. C. Delabie, K. Dumpert, D. J. Williams, and M. Tschirnaus. 2001. Acropyga and Azteca ants (Hymenoptera: Formicidae) with scale insects (Sternorrhyncha: Coccoidea): 20 million years of intimate symbiosis. American Museum Novitates 3335: 1-18.
 * LaPolla J.S. 2004. Acropyga (Hymenoptera: Formicidae) of the world. Contributions of the American Entomological Institute 33(3): 1-130.
 * Silva R.R., and C. R. F. Brandao. 2014. Ecosystem-Wide Morphological Structure of Leaf-Litter Ant Communities along a Tropical Latitudinal Gradient. PLoSONE 9(3): e93049. doi:10.1371/journal.pone.0093049
 * Weber N. A. 1944. The neotropical coccid-tending ants of the genus Acropyga Roger. Ann. Entomol. Soc. Am. 37: 89-122.