Solenopsis interrupta

The sting poison constituents have not been elucidated, but the sting of this insect is reported by Dr. Blum (personal communication) to be excruciatingly painful, much more so than any of the other species encountered by Dr. Blum in South America or in his experience with the two imported species in North America. (Buren 1972)

Distribution based on Regional Taxon Lists
Neotropical Region: Argentina, Bolivia.

Nomenclature

 *  interrupta. Solenopsis saevissima var. interrupta Santschi, 1916e: 379 (w.) ARGENTINA. Subspecies of saevissima: Creighton, 1930b: 89. Raised to species: Wilson, 1952b: 51. See also: Buren, 1972: 22; Trager, 1991: 178.

Worker
Buren (1972) - Head length .81 to 1.67 mm, width .69 to 1.79 mm; in majors length 1.59 to 1.67 mm, width 1.63 to 1.79 mm. Thorax 1.73 to 2.14 mm. long in majors. Scapes 1.06 to 1.12 mm. in majors.

Head strongly cordate in large workers, much broader behind than in front; with large, well developed occipital robes, and strong occipital excision. Ocellar pit deep, in large workers a developed ocellus often present. Scapes very short in large workers, often reaching only about mid-way between eyes and occipital lobe peaks. Eyes much smaller than in blumi, comparing workers of the same head wdth. The cordate head shape occurs down through the polymorphic series to about the medium sized workers; only small media with heads with elliptical sides, only minors with heads even slightly wider in front than behind. Scapes in minors slightly surpassing occipital borders.

Thorax of large workers; promesonotum in profile strongly convex as in Solenopsis quinquecuspis and in Solenopsis blumi, but with a different set, primarily in shape of propodeum whose base in large workers slopes downward toward rear, becoming gradually rounded into the declivity. Thorax in profile singular in one point in having mesonotum slope very gradually into the mesopropodeal impression without a sharp break in outline; but propodeum in front arising very sharply and precipitously. Thorax from above robust and very wide but with only weak pronotal shoulders. In large workers mesonotum well developed, sometimes approaching condition seen in blumi; often promesonotal suture distinct and angulate or semi-angulate medially. Petiole and postpetiole large and robust, postpetiole often.47 to.49 mm long, .70 to .73 mm wide in large workers, larger than in any other species of the complex known to me. Postpetiole from above often wider behind than in front, or sides straight and parallel; anterior border feebly to more strongly convex.

Striae on genae similar to those on blumi, usually not reaching the antennal striae mesally. Piligerous foveoli and punctures on head less developed than in either blumi or quinquecuspis, so that the cephalic integument appears much smoother than in those species. Several fine striae and a weak integumental fold often evident immediately mesad to eye. Mesopleura in large workers with very fine striae, these often obliterated and integument smooth and shining on the lower part of this sclerite. Metapleura with somewhat coarse striae, especially toward the rear. Sides of petiole finely punctate. Sides of post petiole densely punctate and opaque. On posterodorsal face, postpetiole shagreened in front, finely punctate in middle and behind, the transverse striae common in other species very weak or absent.

Erect hairs short and stout, not very flexuous; long hairs of head and thorax, usually greatly longer than remainder of pilosity in most species in the saevissima complex, not so clearly differentiated in this species. Pubescent hairs on front face of petiole sparse.

Color distinctive. Gaster very similar to that of Solenopsis richteri, with a large reddish yellow spot on first gastric tergite, remainder of gaster very dark brown or black. Remainder of body largely the same color as the gastric spot; the head, thorax, scapes and legs all reddish yellow, integument somewhat transparent. Mandibles, a small bar mark on front, and petiole and postpetiole somewhat deeper in color, usually brown or reddish brown. Smallest workers may lack gastric spot, otherwise its presence throughout polymorphic series appears uniform. The colors of preserved specimens brighter, i.e., somewhat more reddish, than in Solenopsis saevissima.