Hypoponera punctatissima
Hypoponera punctatissima is a relatively nondescript small, shining brownish yellow to dark brown species with short antennal scapes and minute but conspicuous eyes. Although likely native to the Afrotropics or possibly Central Asia (Delabie & Blard, 2002), the species was first described from hothouses in Germany (Roger, 1859)and has established introduced populations across the nearly all the globe’s warmer regions in addition to many colder regions such as northern Europe and northern North America (Delabie & Blard, 2002). It is most often collected from the leaf litter and rotting wood, and is often found in association with disturbed habitats such as gardens, plantations, and crop fields, in addition to buildings and hothouses in colder climates. In the southeastern United States H. punctatissima is considered a pest species on account of the nuisances and stings caused during the large dispersal flights of the females (Deyrup et al., 2000). The global distribution, biology and reasons for ecological success was reviewed by Delabie and Blard (2002).
Hypoponera punctatissima has a very complicated taxonomic history littered with infraspecific names, synonyms and misidentifications. The material and names associated with H. punctatissima in Europe (Seifert, 2003b)and the Afrotropical and West Palaearctic regions (Bolton & Fisher, 2011)were recently revised. Combined, these two revisions synonymized 16 previously published names with H. punctatissima. Of particular importance to the New World, evidence was marshaled by Bolton & Fisher to synonymize H. ergatandria Forel , which had previously been considered a distinct species in various North American and Caribbean studies. Those authors also synonymized H. schauinslandi (Emery) which Seifert had considered a distinct species based on micro-morphometrics subjected to discriminant analysis.
Hypoponera punctatissima is reported to have been following humans for a very long time, having arrived in Western Europe by 1,000 A.D. (Seifert, 1996; Timmins & Stradling, 1993; Whitehead, 1994), and continuing to invade new regions (Boer et al., 2006; Delabie & Blard, 2002; Harris, 2003; Olsen, 1994). Although the material referred to in the literature may prove to be several distinct species (Bolton & Fisher, 2011; Seifert, 2003b), the introduced range of what is currently considered to be H. punctatissima is rivaled only by M. pharaonis. The introduced range includes Europe (Rasplus et al., 2010), North America (Smith, 1979), Central America, South America (Delabie & Blard, 2002), the Caribbean (Jaffe & Lattke, 1994; Pressick & Herbst, 1973), the Pacific Islands (Sarnat & Economo, In Press; Wilson & Taylor, 1967), New Zealand (Harris, 2003). The African distribution, part of which may be introduced, is given in Bolton & Fisher (2011). See Delabie and Blard (2002)for additional distribution records.
Workers and nests of the species are often quite cryptic and rarely collected. More often the species is detected by flying queens (the males are ergatoid). The species is reported to only occur where temperatures exceed 21°C (Timmins & Stradling, 1993), and preys exclusively on live insects (Harris, 2003). Delabie and Blard (2002)propose that H. punctatissima was able to spread from its warm native range into colder regions by taking advantage of the heat generated by organic decomposition of compost heaps, horse dung, horse stables, chicken dung and other hallmarks of human settlement. The more modern spread of H. punctatissima is associated with the advent of year round heating in houses, greenhouses and hospitals. In tropical countries where H. punctatissima has been introduced, the apparent rarity of the species may be due to the limited nest sites afforded by decomposing matter and wood detritus close to human establishments (Delabie & Blard, 2002). Taylor (1967)suggested that the production of ergatoid males by both H. punctatissima and its close relative H. ragusai (as H. gleadowi) may be related to their success as tramp species through some kind of simplification of nuptial activity.
In Florida, Hypoponera punctatissima may occur in enormous numbers, especially in highly disturbed areas such as urban, suburban, roadsides and improved pastures, and may have considerable impact on some native species (Deyrup et al., 2000). It is reported to nest there in disturbed fields, lawns, edges of ditches, and marsh grass tussocks, and is probably a predator of small soil organisms. The species is often reported as a pest when queens fly in large numbers, stinging when they land on human skin if they are touched, trapped under clothing, or stuck in sweat (Deyrup et al., 2000).
In the southeastern United States H. punctatissima is considered a pest species on account of the nuisances and stings caused during the large dispersal flights of the females.
Diagnosis of worker among Antkey species. Antenna 12-segmented. Antennal scapes do not reach posterior head margin. Eyes small (equal to or less than 5 facets); situated distinctly below midline of head. Frontal lobes relatively narrow. Clypeus with anterior margin flat to convex, but never forming a distinct triangle that projects anteriorly beyond the base of the mandibles. Mandibles triangular; with more than 7 teeth and denticles. Metanotum does not form a prominent convexity bordered by distinct suture lines. Hind coxae lacking dorsal spine. Hind tibia with pectinate spur, but without simple spur. Tarsal claws lacking subapical tooth. Waist 1-segmented. Petiole subrectangular, relatively tall and narrow with a nearly flat anterior face and a strongly convex subpetiolar process; narrowly attached to gaster; conspicuous posterior face. Gaster armed with sting. Distinct constriction between abdominal segments 3+4. Abdominal segment 4 lacking deep longitudinal furrows. Color brownish yellow to dark brown approaching black. Sculpture mostly shining. PeH 0.30–0.39, LPeI 43–53.
Among Antkey species, H. punctatissima is most likely to be confused with H. opaciceps, but can be reliably distinguished by the antennal scapes which fail to reach the posterior head margin (versus reach and slightly exceed the posterior head margin), the more smooth and shining sculpture (especially the mesopleuron region), and the relatively shorter and broader petiole with the anterior and posterior faces slightly converging apically. Another species more easily confused with H. punctatissima is H. ragusai. Although H. ragusai is known from Maryland, USA (as Ponera gyptis Santschi), it has long been misidentified as H. punctatissima and records previous to Bolton & Fisher (2011)may require reexamination. This is especially true for Hawaii and other Pacific Islands. Hypoponera punctatissima can be distinguished by (1) the petiolar node, which in profile is relatively shorter and higher (LPeI 43–53); and (2) in dorsal view the petiolar node is relatively shorter from front to back, (DPeI 140–165). According to Bolton & Fisher (2011), in addition to differences in the shape of the petiolar node, H. ragusai workers are always yellow to light brownish yellow, fall at the bottom end of the known size range of H. punctatissima (e.g. HW 0.42–0.50, versus 0.46– 0.60 in H. punctatissima) and have heads that average relatively slightly narrower and scapes that are relatively slightly longer than in H. punctatissima; compare CI and SI above with CI 79–87 and SI 75–84 in H. punctatissima. Finally, the queen of H. ragusai is considerably darker in color than her workers, whereas in H. punctatissima the two castes have the same color.
Hypoponera rugasai
Native range. Old World. Likely African in origin, but Central Asia has also been proposed.
Introduced range. Cosmopolitan tramp species. Occurs outdoors across tropical/subtropical habitats and indoors in more temperate climates.