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Subfamily PONERINAE
Tribe PONERINI

Hypoponera opaciceps (Mayr, 1887)
"granulate mini-ponerine ant"

Authors: Joe A. MacGown and Ryan J. Whitehouse
Uploaded 2009; last updated 1 December 2016

Hypoponera opaciceps, full face view of a worker (MS, Noxubee Co.) (photo by James G. Lewis and Joe A. MacGown)

Hypoponera opaciceps, lateral view of a worker (MS, Noxubee Co.) (photo by James G. Lewis and Joe A. MacGown)
Hypoponera opaciceps, dorsal view of a worker (MS, Noxubee Co.) (photo by James G. Lewis and Joe A. MacGown)
Hypoponera opaciceps, full face view of a female (MS, Jackson Co.) (photo by Ryan J. Whitehouse and Joe A. MacGown)
Hypoponera opaciceps, lateral view of a female (MS, Jackson Co.) (photo by Ryan J. Whitehouse and Joe A. MacGown)
Hypoponera opaciceps, dorsal view of a female (MS, Jackson Co.) (photo by Ryan J. Whitehouse and Joe A. MacGown)
Hypoponera opaciceps, lateral view of a female (MS, Jackson Co.) (photo by Ryan J. Whitehouse and Joe A. MacGown)
Hypoponera opaciceps, full face view of a male (MS, Jackson Co. ) (photo by James G. Lewis and Joe A. MacGown)
Hypoponera opaciceps, lateral view of a male (MS, Jackson Co. ) (photo by James G. Lewis and Joe A. MacGown)

Hypoponera opaciceps, lateral view of a worker showing petiole (MS, Noxubee Co.) (photo by James G. Lewis and Joe A. MacGown)

Introduction
Hypoponera ants can be found around the world and are considered to be the most common and diverse Ponerinae ant species worldwide with 177 species. They can be found on the ground or just under the surface and nest in leaf litter, rotten wood and the soil. Some Hypoponera species are known to have unique reproductive strategies including ergatoid males and females and male mate competition.

Hypoponera species can be identified by having a waist with only one distinct segment; gaster being narrowly connected to the waist; presence of a stinger; apex of gaster pointed downwards or posteriorly; frontal lobes covering base antennal insertion point; head and body relatively smooth; mandibles triangular; only one pectinate spur on hind tarsi; and subpetiolar process simple and not toothed.

Hypoponera opaciceps (Mayr) (Ponerinae) is a medium sized, dark brown to brownish black species native to South America. This species has been established in the US for many years where it occurs from South Carolina south to Florida and west to California. It was reported from Mississippi as early as 1929 by M. R. Smith (1929).  

Taxonomic History (Bolton 2016)
Ponera opaciceps Mayr, 1887: 536 (w.q.) BRAZIL. Neotropic. Smith, 1929: 545 (m.); Wheeler & Wheeler, 1964: 453 (l.). Combination in Hypoponera: Taylor, 1967: 11. Senior synonym of Hypoponera perkinsi (and its junior synonym Hypoponera andrei):Wilson & Taylor, 1967: 28; of Hypoponera postangustata: Wild, 2007: 54. Current subspecies: nominal plus Hypoponera opaciceps cubana, Hypoponera opaciceps gaigei, Hypoponera opaciceps jamaicensisHypoponera opaciceps pampana. See also: Smith, 1936: 428; Wheeler, 1937: 59; Kempf, 1962: 7.

Identification
Worker: Small (TL ≈ 3.0–5 mm, HL 0.08–0.83 mm, HW 0.67–0.72 mm, SL 0.60–0.64 mm, EL 0.04–0.06 mm, MeSL 1.04–1.07 mm) (n=5). Head and body reddish-brown to brownish black; legs, funiculus and mandibles reddish brown. Head longer than wide, rounded rectangular, with fine punctation and dense short, appressed setae giving it a velvety look; frontal lobes prominent, covering antennal insertions; eye reduced and located laterally on anterior 1/4 of the head; mandibles elongate triangular, outer borders more or less straight, apical tooth longest with numerous smaller teeth and denticles along inner borders; antenna 12-segmented, funiculus gradually becoming clavate apically. Mesosoma broadly convex in profile view; promesonotal and metanotal sutures present, but not deeply impressed; propodeum gently sloped, slightly concave entire mesosoma with fine punctation and dense appressed, short setae. Waist with a single petiolar node; node relatively tall, approximately the same width throughout its height; subpetiolar process simple, rounded, lacking teeth or a fenestra (as in Ponera species). Gaster with first two segments elongate and about twice the size of the remaining segments or longer; first segment overlapping the second; entire gaster with  dense, short setae and with longer, erect setae that become more conspicuous near apex; long, curved sting present.

Queen: Small, slightly larger than workers (TL ≈ 3.7–4.0 mm, HL 0.82–0.86 mm, HW 0.72–0.76 mm, SL 0.64–0.68 mm, EL 0.18–0.20 mm, MeSL 1.16–1.28 mm) (n=5). Head and body reddish-brown to brownish black; legs, funiculus and mandibles reddish brown. Head longer than wide, rounded rectangular, with fine punctation and dense, short, appressed setae; frontal lobes prominent, covering antennal insertions; ocelli present; eyes large, located on anterior 1/3 of head; mandibles elongate triangular, outer borders more or less straight, apical tooth longest with numerous smaller teeth and denticles along inner borders; antenna 12-segmented, funiculus gradually becoming clavate apically. Mesosoma enlarged, blocky rectangular; pronotum somewhat rectangular in lateral view; mesopleural suture present; propodeal declivity strongly angled; entire mesosoma with fine punctation and dense appressed, short setae. Wings hyaline, veins and pterostigma light yellowish, each wing with a submarginal and discal cell. Waist with a single petiolar node; node slightly narrower apically than basally; subpetiolar process simple, rounded, lacking teeth or a fenestra (as in Ponera species). Gaster with first two segments elongate and about twice the size of the remaining segments or longer; first segment overlapping the second; entire gaster with  dense, short setae and with longer, erect setae that become more conspicuous near apex; long, curved sting present.

Male: Smaller than worker (TL ≈ 3.01–3.2 mm, HL 0.63–0.69 mm, HW 0.50–0.59 mm, SL 0.11–0.12 mm, EL 0.30–0.33 mm, MeSL 1.12–1.23 mm). (n=5). Head, body, coxae and funiculi (excluding pedicel) brown; scape, pedicel, and legs yellowish brown. Head circular,  with dense, short, appressed setae; clypeus with three long medial setae projecting anteriorly; eye large, approximately half of the length of the head; three large ocelli medially present on the posterior apex of the head; mandibles reduced, edentate; antenna 13-segmented, filiform lacking club. Mesosoma enlarged, rounded convexly; pronotum rectangular; mesopleural suture present; propodeal declivity gently curved; entire mesosoma with dense appressed, short setae. Wings hyaline, veins and pterostigma light yellowish, each wing with a submarginal and discal cell. Waist with a single petiolar node; node rounded triangular, much wider basally than apically; subpetiolar process rounded.  Gaster with first two segments elongate and about twice the size of the remaining segments or longer; entire gaster with  dense, short setae and with longer, erect setae that become more conspicuous near apex; genitalia conspicuous, parameres large.

Hypoponera opaciceps can be separated from similar species in the southeastern US by the presence of a simple, rounded subpetiolar process that lacks teeth, dark color and the petiole staying the same width throughout its height. Similar species include H. opacior, which differs by having the petiole (of workers) in profile gradually tapering apically; and Ponera pennsylvanica, which differs (in workers and queens) by the subpetiolar process with two distinct teeth posteriorly and with a circular fenestra present anteriorly. Other species of Hypoponera and Ponera in the Southeast are much smaller in size.

Biology and Economic Importance
Not much is known about Hypoponera opaciceps’s behavior and biology. It is commonly found in leaf litter and suspected to forage on leaf mold. It is rarely found foraging in the open and has not been reported at baits. Based on MEM records, H. opaciceps specimens are often collected in disturbed open and wooded habitats such as in open wooded areas at recreational parks, nesting between shells on shell middens, in disturbed bottomland forest sites, in open fields with cogon grass, in disturbed mixed pine/hardwood forests, and nesting in piles of pine bark left over from logging pine trees. This species has been found nesting in potted plants.

Hypoponera opaciceps is considered an economically important species. It has spread across the Nearctic and Neotropical regions quite efficiently. Colonies can commonly be found in potted plants and soil and it is suspected that Florida’s plant nurseries have inadvertently aided in H. opaciceps spread. Soil ballasts used by ships taken from infested beaches probably also played a part in the spread of this species. This species is not aggressive, but has a sting, and may sting if disturbed.

Distribution
Native Range: South America

Australian: American Samoa, Federated States of Micronesia, Fiji, French Polynesia, Hawaii, New Caledonia, New Guinea, Palau, Samoa, Tonga (AntWiki.org).
Nearctic: United States (MEM).
Neotropical: Argentina, Bahamas, Bermuda, Brazil, Costa Rica, Cuba, Dominican Republic, Ecuador, Galapagos Islands, Guatemala, Guyana, Haiti, Honduras, Lesser Antilles, Mexico, Panama, Paraguay, Peru, Puerto Rico, Trinidad and Tobago, Uruguay (AntWeb.org and AntWiki.org).
Oriental: Philippines (AntWiki.org).
Palearctic: China, Japan (AntWiki.org).

U.S. Distribution: AL, AR, AZ, CA, CO, FL, GA, HI, LA, MS, NC, NM, SC, TX, UT, VA, WA (AntWeb.org and MEM).
Southeastern U.S. Distribution: AL, AR, FL, GA, LA, MS, NC, SC (MEM).

Acknowledgments
Funding for the ant work being done by the MEM in Alabama and Mississippi is from several sources including the National Institute of Food and Agriculture, United States Department of Agriculture, under Project No. MIS-012040, the Mississippi Agricultural and Forestry Experiment Station at Mississippi State University, with support from State Project MIS-311080, NSF Grants BSR-9024810 and DFB-9200856, the Tombigbee National Forest (U.S. Forest Service), the Noxubee Wildlife Refuge, Mississippi Natural Heritage Program Research Grant, USDA Forest Service Agreement No. 08-99-07-CCS-010, the William H. Cross Expedition Fund, and primarily by the USDA-ARS Areawide Management of Imported Fire Ant Project (2001-2014) and USDA-ARS Areawide Management Invasive Ants Project. Additionally, special cooperation has been provided by State Parks, National Forests, National Wildlife Refuges, the Natchez Trace Parkway, and from various private landowners in both Alabama and Mississippi.

Literature Cited

Bolton, B. 2016.  Bolton World Catalog Ants. Available online: http://www.antweb.org/world.jsp. Accessed 9 March 2016.

Kempf, W. W. 1962. Miscellaneous studies on Neotropical ants. II. (Hymenoptera, Formicidae). Studia Entomologica 5:1-38.

Mayr, G. 1887. Südamerikanische Formiciden. Verhandlungen der Kaiserlich-Königlichen Zoologisch-Botanischen Gesellschaft in Wien 37:511-632.

Smith, M. R. 1929. Descriptions of five new North American ants, with biological notes. Annals of the Entomological Society of America 22: 543-551. 

Smith, M. R. 1936. Ants of the genus Ponera in America, north of Mexico. Annals of the Entomological Society of America 29:420-430.

Taylor, R. W. 1967. A monographic revision of the ant genus Ponera Latreille (Hymenoptera: Formicidae). Pacific Insects Monograph 13:1-112.

Wheeler, G. C.; Wheeler, J. 1964. The ant larvae of the subfamily Ponerinae: supplement. Annals of the Entomological Society of America 57:443-462.

Wheeler, W. M. 1937. Mosaics and other anomalies among ants. Cambridge, Mass.: Harvard University Press, 95 pp.

Wild, A. L. 2007. A catalogue of the ants of Paraguay (Hymenoptera: Formicidae). Zootaxa 1622:1-55.

Wilson, E. O.; Taylor, R. W. 1967. The ants of Polynesia (Hymenoptera: Formicidae). Pacific Insects Monograph 14:1-109.

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