Solenopsis enigmatica

Identification
Deyrup & Prusak (2008) - Worker. Distinguished from other Solenopsis workers by clypeal morphology: clypeus lacking carinae, in lateral view rounded and strongly declivitous. Pale yellow, antennal scapes short, in frontal view failing to reach occipital margin of head by a distance about equal to the combined length of the first 4 segments of the funicle. If S. phoretica produces workers, they might be similar to those of enigmatica, so this diagnosis may not be definitive.

Dealate Female. Distinguished from most other Solenopsis by the form of the mandibles, which are falcate, with the teeth not in an oblique series, as normal in species of Solenopsis; the basal angle is strongly developed and weakly bidentate, the concave inner margin with a low, median double tooth; Solenopsis phoretica lacks this median double tooth.

Distribution based on Regional Taxon Lists
Neotropical Region: Dominica.

Nomenclature

 *  enigmatica. Solenopsis enigmatica Deyrup & Prusak, 2008: 71, figs. 1-2 (w.q.) DOMINICA.

Worker
Paratype. Total length (length of head excluding mandibles + length of mesosoma + length of petiole + length of postpetiole + length of gaster): 2.27; head length: 0.50; head width at rear margins of eyes in frontal view: 0.45; length of mesosoma: 0.60; length of petiole: 0.20; length of postpetiole: 0.12; length of gaster: 1.55. Color: pale yellow, eyes black. Head: smooth, shining, with scattered setigerous punctures, including a series of 4 large, posteriorly-directed, suberect, slightly convergent setae on each side of frontal area, and several small, decumbent, convergent setae on each side of frontal area; eye composed of a single, large, dark facet; mandibles unlike those of queen, more typical of workers of other small Solenopsis species: apical tooth long and sharp, remaining 3 teeth small, sharp, in a strongly oblique series, with a long, toothless proximal inner margin; clypeus without carinae, convex in lateral view, with four subapical elongate setae and a long median apical seta; antennae 10-segmented, scapes in frontal view failing to reach occipital margin by a distance about equal to the first 4 segments of the funicle; antennal club 2-segmented. Mesosoma smooth, shining, pronotum with 3 large, semierect, posteriorly-directed setae on each side, and 1 smaller, semierect, anteriorly-directed seta on each side at posterior margin of pronotum; propodeal spiracle large, as in Fig. 2; legs smooth, shining, with sparse, strong, semidecumbent, distally- directed hairs; hind basitarsus about the length of hind tibia. Petiole: apex of node in posterior view somewhat flattened; node with two long, posteriorly-directed setae on each side near apex; ventral process a low, triangular tooth, somewhat rounded apically. Postpetiole: low and rounded above in lateral view; in dorsal view 5/7 as long as wide. Gaster: first tergite with sparse, long, suberect, posteriorly-directed hairs that are generally distributed; tergites 2-4 smooth each with an irregular row of large, suberect, subapical hairs; sting slightly extruded.

Queen
Holotype Dealate. Features visible in lateral view, described from left side, mm. Total length (length of head excluding mandibles + length of mesosoma + length of petiole + length of postpetiole + length of gaster): 3.92; head length: 0.60; head width at rear margins of eyes in frontal view: 0.62; length of mesosoma: 1.20; length of petiole: 0.37; length of postpetiole: 0.20; length of gaster: 1.55. Color: yellowish brown, ocellar triangle dark brown, appendages yellow. Head: smooth, shining, sparsely covered with setigerous punctures separated by 2-8 times the width of a puncture in frontal area, 2-4 times the width of a puncture on sides, setae suberect, directed posteriorly in frontal area, elsewhere directed anteriorly; ocelli not enlarged, each ocellus about the width of antennal scape near base; malar distance about half (4/7) length of eye; mandibles elongate, a little less than half the length of the head at midline; mandible with basal angle strongly developed, bidentate; inner margin of mandible strongly concave distal to basal angle, with a low, median, marginal double tooth, the proximal cusp blunt but conspicuous, the distal cusp reduced to a low ridge; clypeus declivitous, concave, without carinae, with 4 subapical elongate setae; antennae 10-segmented, scapes reaching outer corner of head in frontal view, antennal club 2-segmented, club about as long as remainder of funiculus. Mesosoma: smooth and shining, with sparse setigerous punctures on pronotum and near margins of mesonotum, mesopleura, sides of propodeum; katepisternum with sparse setigerous punctures; disc of mesonotum and declivity of propodeum not punctate; propodeum evenly declivitous in lateral view; legs smooth, shining, with sparse, strong, semidecumbent, curved, distally directed hairs; hind basitarsus longer than hind tibia; a dense, coarse, ventral brush of hairs on distal half of front basitarsus. Petiole: peduncle short, less than 0.25 length of base of petiole in lateral view; node of petiole in lateral view triangular, apex broadly and smoothly rounded, in posterior view semicircular; ventral process narrowly expanded, with a small ventral projection that is like a low ridge rather than a tooth. Postpetiole: low and rounded above in lateral view, in posterior view about 1.5 times as wide as long. Gaster: in dorsal view first tergite with prominent, rounded anterior corners, projecting forward from midline; first gastral tergite and sternite each with a broad, median, basal concavity; first tergite with sparse, long, suberect, posteriorly-directed, hairs that are generally distributed; tergites 2-4 smooth, each with an irregular row of large, suberect, subapical hairs.