Acropyga acutiventris

A common wide-ranging species, A. acutiventris is known to occur in rainforest and, in Australia, savanna woodlands. Nests are located in rotten wood on the ground, under stones, and in the leaf litter. This species is a trophophoretic ant that has been found to be associated with two species of mealybugs (Xenococcus acropygae and X annandalei). Queens carry live mealbugs in their mandibles on their nuptual flights, with the mealybugs providing honeydew for her newly established nest.

Identification
From Lapolla (2004):

Diagnosis - Worker: 11 segmented antennae; mandible with 5 teeth and distinct ridges that run along dorsal surface; many erect hairs on head, mesosoma and gaster giving ant a "spiky appearance"; eyes prominent. Queen: As in worker with modifications expected for caste. Male: 12 segmented antennae; parameres with dense covering of erect hairs and with dorsolateral expansions medially. Compare with Acropyga rubescens.

This species is fairly easy to recognize, with the only morphologically similar species being its close relative, Acropyga rubescens. A combination of large eyes (more than 20 facets), unique mesosomal shape, and 5-toothed mandibles with distinct striate sculpture on the dorsal surface, enable identification of A. acutiventris. Separating workers of this species from A. rubescens can be more difficult, though in general it is not as hairy as in A. rubescens, is slightly smaller in total length, and the striate sculpture extends approximately across the entire dorsal surface of the mandible. Males of A. acutiventris are also less hairy than in A. rubescens, but the most reliable means to identify them is by dissecting out the penis valves, which are distinct for each species. Given the large range and morphological variability of this species, it is not surprising that so many synonyms have been created. In the past, species have been based on variation in color, overall size, head shape differences and antennal segment shape differences. Here, they are all treated as being the same of a wide ranging, variable species. Dissection of males from across the range (penis valve dissections from Australia, India, Papua New Guinea, Singapore, and the Solomon Islands) of A. acutiventris revealed no discernable genitalic differences.

Australia
Within Australia this species can be separated from other members of the genus by the presence of long erect hairs on the antennal scapes and posterior margin of the head.

Distribution based on Regional Taxon Lists
Australasian Region: Australia. Indo-Australian Region: Borneo, Indonesia, Krakatau Islands, Papua New Guinea, Philippines, Singapore, Solomon Islands. Oriental Region: India, Nicobar Island, Sri Lanka, Thailand, Vietnam. Palaearctic Region: China.

Acropyga acutiventris has a large range that occupies much of the Australasian, Indo-Australian, and Oriental regions. It can be found from India east to northern Australia. It is one of the most commonly encountered species in the genus.

Australia
Limited to the Top End and northern Queensland where it occurs primarily in rainforest with a few records from savanna woodlands.

Nomenclature

 *  acutiventris. Acropyga acutiventris Roger, 1862a: 243 (w.q.) SRI LANKA. Imai, Brown, et al. 1984: 68 (k.). Senior synonym of flava: Forel, 1894c: 418; of australis: Taylor, 1992a: 58; of carinata, crassicornis, indosinensis, javana, moluccana, mysolensis, occipitalis, opaca, papuana, undecemus: LaPolla, 2004a: 31. See also: Terayama, Fellowes & Zhou, 2002: 23.
 * flava. Plagiolepis flava Mayr, 1862: 699 (q.m.) NICOBAR IS. Combination in Acropyga: Mayr, 1862: 769. Junior synonym of acutiventris: Forel, 1894c: 418.
 * moluccana. Acropyga moluccana Mayr, 1879: 658 (w.) INDONESIA (Seram I.). Karavaiev, 1933a: 310 (q.m.); Wheeler, G.C. & Wheeler, J. 1953c: 137 (l.). Junior synonym of acutiventris: LaPolla, 2004a: 31.
 * crassicornis. Acropyga crassicornis Emery, 1900d: 698 (footnote), fig. 13 (w.) NEW GUINEA. Junior synonym of acutiventris: LaPolla, 2004a: 31.
 * australis. Acropyga moluccana var. australis Forel, 1902h: 477 (w.) AUSTRALIA. Wheeler, G.C. & Wheeler, J. 1968: 209 (l.). Subspecies of acutiventris: Forel, 1911e: 286; of moluccana: Taylor & Brown, D.R. 1985: 108. Junior synonym of acutiventris: Taylor, 1992a: 58; LaPolla, 2004a: 31.
 * mysolensis. Acropyga moluccana subsp. mysolensis Forel, 1911e: 285 (w.) INDONESIA (Misool I.). Junior synonym of acutiventris: LaPolla, 2004a: 31.
 * opaca. Acropyga moluccana var. opaca Stitz, 1911a: 370 (w.) NEW GUINEA. Donisthorpe, 1948g: 139 (m.). Junior synonym of acutiventris: LaPolla, 2004a: 31.
 * occipitalis. Acropyga moluccana var. occipitalis Stitz, 1912: 510, fig. 12 (w.) NEW GUINEA. Junior synonym of acutiventris: LaPolla, 2004a: 31.
 * papuana. Acropyga (Acropyga) moluccana subsp. papuana Mann, 1919: 364 (w.) SOLOMON IS. Wheeler, G.C. & Wheeler, J. 1953c: 136 (l.). Junior synonym of acutiventris: LaPolla, 2004a: 31.
 * silvestrii. Acropyga (Rhizomyrma) silvestrii Wheeler, W.M. 1927h: 100, fig. 7 (w.) VIETNAM. [Junior primary homonym of silvestrii Emery, above.] Replacement name: indosinensis Wheeler, W.M. 1935c: 72.
 * carinata. Acropyga acutiventris var. carinata Karavaiev, 1933a: 310 (w.) INDONESIA (Sumatra). Junior synonym of acutiventris: LaPolla, 2004a: 32.
 * javana. Acropyga (Acropyga) acutiventris var. javana Karavaiev, 1933a: 308 (w.m.) INDONESIA (Java). Junior synonym of acutiventris: LaPolla, 2004a: 31.
 * indosinensis. Acropyga (Rhizomyrma) indosinensis Wheeler, W.M. 1935c: 72. Replacement name for Acropyga silvestrii Wheeler, W.M. 1927h: 100. [Junior primary homonym of Acropyga silvestrii Emery, 1915g: 21.] Junior synonym of acutiventris: LaPolla, 2004a: 32.
 * undecemus. Pseudolasius undecemus Donisthorpe, 1949c: 756 (w.) NEW GUINEA. Combination in Acropyga: Bolton, 1995b: 58. Junior synonym of acutiventris: LaPolla, 2004a: 32.

Worker
LaPolla (2004) - Head: yellow to light brownish-yellow; head about as broad as long; posterior margin concave; covered in a thick layer of appressed hairs, with many scattered erect hairs, especially along posterior margin; eyes relatively large, placed at lower 1/4 of head; 11 segmented, incrassate antennae; scape reaches or surpasses posterior margin by about length of pedicel; clypeus broad, slightly convex medially with many erect hairs, the longest ones along anterior clypeal margin; mandible with 5 uneven teeth; 3rd and 5th tooth (from apical to basal) smaller than others; dorsal surface of mandible with distinct ridges across surface from about base of teeth toward insertion of mandibles; slight gap present between inner mandibular surface and anterior clypeal margin. Mesosoma: yellow to light brownish-yellow; pronotum in lateral view typically with short shelf before rising sharply toward mesonotum; mesonotum rounded with many erect and appressed hairs at apex; metanotal area distinct; propodeum below level of mesonotum, dorsum flat before steep declivity; propodeum with short erect and appressed hairs. Gaster: yellow to light brownish-yellow to reddish-yellow; petiole thick and erect reaching height of propodeum; yellow to light brownish-yellow; gaster covered in thick layer of appressed hairs with many scattered erect hairs throughout giving a "spiky" appearance.

Measurements (n=l0): TL: 2.67-3.53; HW: 0.8-0.912; HL: 0.803-0.896; SL: 0.628-0.827; ML: 0.836-1.03; GL: 0.933-1.74; CI: 91.07-104.25; SI: 78.7-97.97.

Queen
LaPolla (2004) - As in worker with modifications expected for caste.

Measurements (n=3): TL: 4.56-5.09; HW: 1.02-1.06; HL: 0.967-1.01; SL: 0.902-0.971; ML: 1.4-1.63; GL: 2.19-2.63; CI: 102.97-106; SI: 85.09-95.2.

Male
LaPolla (2004) - Head: yellow to light brownish-yellow, darker around three prominent ocelli; head about as broad as long; covered in layer of appressed hairs with scattered suberect to erect hairs; 12 segmented, slightly incrassate antennae; scape surpasses posterior margin by about length of first two funicular segments; clypeus broad, relatively flat, with scattered short erect hairs; mandible with 3-4 teeth; gap present between inner mandibular margin and anterior clypeal margin. Mesosoma: yellow to light brownish-yellow; pronotum short and collar-like; mesonotum large, rounded anteriorly; mesonotum flat dorsally, with layer of shorter appressed hairs and scattered longer erect hairs throughout; propodeum lower than mesonotum and scutellum; declivity not distinct from propodeum. Gaster: petiole thick and erect; gaster yellow to light brownish-yellow to reddish-yellow, darker dorsally; covered in dense layer of appressed hairs with scattered erect hairs throughout. Genitalia: in lateral view parameres thick, tapering to rounded apices; parameres with medial dorsolateral extensions; cuspi short, bent toward approximately middle of digiti, where cuspi meet digiti with short, peg-like teeth at apices; digiti long and erect; apex rounded; digiti with short-peg-like teeth where cuspi meet.

Measurements (n=3): TL: 2.89-3.33; HW: 0.604-0.644; HL: 0.588-0.626; SL: 0.529-0.617; ML: 1.03-l. l6; GL: 1.27-1.56; CI: 102.72-103.09; SI: 87.58-95.81.

Additional References

 * LaPolla, J.S. (2004) Acropyga of the world. Contributions of the American Entomological Institute, 33(3): 1-130.
 * Forel, A. (1902) Fourmis nouvelles d'Australie. Revue Suisse de Zoologie, 10: 405–548.
 * Forel, A. (1911) Die Ameisen des K. Zoologischen Museums in München. Sitzungsberichte der Mathematischen-Physikalischen Klasse der Königlich Bayerischen Akademie der Wissenschaften zu München, 11: 249–303.
 * Roger, J. (1862) Einige neue exotische Ameisen-Gattungen und Arten. Berliner Entomologische Zeitschrift, 6: 233–254.
 * Taylor, R. W., Brown, D. R. (1985) Formicoidea. pp. 1–149 in Walton, D. W. Zoological catalogue of Australia, vol. 2. Hymenoptera: Formicoidea, Vespoidea and Sphecoidea. Canberra: Australian Government Publishing Service. vi + 381 pp.
 * Taylor, R. W. (1992) Nomenclature and distribution of some Australian and New Guinean ants of the subfamily Formicinae. Journal of the Australian Entomological Society, 31: 57–69.