Hypoponera opaciceps
Hypoponera opaciceps is a small reddish-brown to blackish species with very small eyes, a densely punctate and opaque sculpture, antennal scapes that barely exceed the posterior head margin, and a nearly rectangular petiole with parallel anterior and posterior faces and a flat to weakly convex dorsal face. Hypoponera opaciceps is mostly limited to forested habitat where it nests opportunistically and forages in and around rotting logs, soil and leaf litter. The species is almost entirely blind, and is not often encountered foraging out in the open, nor is it known to recruit to food baits. The species is widely introduced across the globe (Wilson & Taylor, 1967). Interestingly, H. opaciceps produces ergatoid males. Despite being widely distributed and associated with disturbance, H. opaciceps is not considered to be a significant pest species. Hypoponera opaciceps was redescribed by Smith (1936)and Kempf (1962).
In the New World it ranges this species ranges from as far north as Boulder, Colorado, in the United States to as far south as Uruguay, South America, and throughout the islands of the West Indies (Smith, 1936). It is presumably native much of this range, including South America (Wild, 2007). In the Old World, its distribution is patchier, but is particularly widespread across the Pacific Islands. The exact native range of H. opaciceps is unclear, however. Ward (Ward, 2005), for example, lists the species as possibly introduced to California, but might be native to nearby regions. The ant is considered by some to be native to Florida (Deyrup, 2003; Deyrup et al., 1988)and Louisiana (Dash & Hooper-Bùi, 2008), but introduced to Mississippi (MacGown et al., 2009). The Antweb record (LACM ENT 142427) from a hothouse in Washington State is more definitively representative of an introduction. The Afrotropical and West Palaearctic taxa previously considered to be subspecies of H. opaciceps have all been revised as synonyms of other Hypoponera species (Bolton & Fisher, 2011).
In Hawaii H. opaciceps is found in lowland and montane ecosystems (Reimer, 1994). It most often occurs in areas between 600–1200 m, but was collected as high as 2700 m and as low as 150 m. The Hawaiian populations form small colonies of less than 50 workers in the soil and under rocks, and is one of the few species that has been able to penetrate wet undisturbed rainforest. It is reported there to be a relatively innocuous species that has an insignificant effect on the native fauna.
Hypoponera opaciceps is not considered to be a significant pest species.
Diagnosis of worker among Antkey species. Antenna 12-segmented. Antennal scapes exceed 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 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 reddish brown to black. Sculpture strongly punctate on head and body.
Hypoponera opaciceps, as it is currently defined, can be a highly variable species with respect to sculpture, length of antennal scapes and size (Kempf, 1962; Smith, 1936). Among Antkey species, H. opaciceps is most likely to be confused with H. punctatissima and H. ragusai, but can be separated from them by the antennal scapes which reach and slightly exceed the posterior margin of the head ( versus fail to reach), the uniformly punctate sculpture across the entire head and body, and the more rectangular petiole with parallel anterior and posterior faces ( versus more faces that converge towards each other apically).
Hypoponera punctatissima, Hypoponera ragusai
Native range. New World: Southern United States to southern South America and the Caribbean.
Introduced range. Pacific Islands including: Hawaii, Fiji, French Polynesia, Marquesas, New Caledonia, Philippines, Samoa, Taiwan.