Solenopsis rosella

From Kennedy 1938, "This ant can be found in coarse moist sand at high beach level. Nest No. 1372 was found eight inches to one side of a nest of Iridomyrmex analis pruinosa (=Forelius pruinosus) in coarse sand along the west side of a sand-spit on the south shore of Pelee Island, Ontario." The junior author and Emma Mackay found that most of Pelee point had eroded away and spent a couple of days looking for them in 2007. We finally found them on the west side beach in a nest of Formica schaufussi at about dark. We searched the surrounding area in Ontario but did not find them. No queens or males were found. In 2009 we checked the south side of Lake Erie in the United States and were unable to find them, so they are apparently found only in one location in Canada.

Identification
A New World thief ant that is a member of the molesta species complex. (Key to New World Solenopsis Species Complexes)

Pacheco and Mackay (2013) – Worker - Workers are small, pale yellow ants. The head is longer than wide with the posterior border depressed medially. The cephalic punctures are semicoarse, resembling those of the pygmaea complex. The lateral clypeal teeth are developed only into small, blunt angles and the extralateral teeth are absent. The clypeal carinae are present, but not well developed. The petiolar node is triangular and a miniscule flange is present on the subpeduncular process. Queen - The queen is pale yellow in color with a pink gaster (when alive, they become yellow in pinned specimens) and moderately large. The head is semi-quadrate and slightly longer than wide. The cephalic punctures are coarse, resembling those found with the fugax species complex. The eyes extend 0.060 mm past the lateral margin of the head. The medial ocellus is relatively large. The subpeduncular process has a small tooth. Male - The male is slightly bicolored with a brownish head and gaster and pale yellow body. The head is as long as wide. The antennae are pale yellow in color. The eyes of the male are large and extend 0.72 mm past the lateral margin of the head. Vertical striae are present between the frontal lobes and below the medial ocellus. Horizontal striae are present lateral to the torulae and eye. There is a small tooth present on the subpeduncular process.

It is helpful to have a queen as part of the series in order to identify this species. The queen is relatively large, pale yellow with relatively large eyes. If one has queens of a series, they are easily recognized by the color and the size of the eye. Without queens, identification is very difficult, as workers are easily confused with the smaller workers of Solenopsis texana. However, S. rosella is from Canada and S. texana's northern limits are the upper part of New Mexico and Oklahoma in the mid and southwest and Virginia in the East.

This species could be confused with and is most similar to Solenopsis molesta based on the similarities between the queens, but S. rosella queens when alive exhibits a pinkish tint to its cuticle as is seen with S. texana. Additionally, S. molesta queens are slightly larger in size at 5 mm in total length and more often have a tooth present on the subpeduncular process.

Solenopsis rosella was considered to be a synonym S. texana (Creighton 1950). The workers are very similar to S. texana, but queens are nearly identical to S. molesta (except most queens of molesta have a large subpeduncular process, lacking in S. rosella) and are different from those of S. texana. Solenopsis rosella can be separated from S. texana based on the queen that is large (total length ~ 4.5 mm) and yellow, much larger than the queen of S. texana and much brighter in color than the brown queen of S. texana. Additionally the eyes of the queen are large (0.250 mm greatest diameter), similar to the eyes of S. molesta and much larger than the eyes of S. texana (0.160 mm greatest diameter).

Distribution
Pelee Point, and Pelee Island, Ontario, Canada, the most southern point in Canada.

Distribution based on Regional Taxon Lists
Nearctic Region: Canada.

Nomenclature

 *  rosella. Solenopsis rosella Kennedy, 1938: 232, figs. 1-3, 5, 6, 8, 10 (w.q.m.) CANADA.
 * Junior synonym of texana: Creighton, 1950a: 238; Ettershank, 1966: 144; Bolton, 1995b: 390.
 * Status as species: Smith, M.R. 1943a: 211 (in key); Smith, M.R. 1951a: 814; Pacheco & Mackay, 2013: 288 (redescription).

Worker
Pacheco and Mackay (2013) - Measurements (n=1). TL 1.44; HL 00408; HW 0.360; EL 0.060; ED 0.030; SL 0.276; FSL 0.108; CI 88.2; SI 67.7; PL 0.078; PW 0.108; PI 72.2; PPL 0.120; PPW 0.126; PPI 95.2; WL 0.282; PSL 0.042; PSW 0.030.

Small, concolorous pale yellow; head longer than wide; cephalic punctures semi-coarse; medial clypeal teeth angular, extralateral teeth absent; clypeal carinae weakly developed; scape does not reach posterior lateral margin of head; minor segments of funiculus 0.108 mm in total length; eyes small (five ommatidia); notopropodeal suture depressed, groove breaks sculpture of mesosoma; posterior propodeal margin slightly angled; propodeal spiracle relatively small; fine horizontal striae present on metapleuron; petiole wider than postpetiole viewed laterally; petiolar node triangular, small flange at subpeduncular process; petiole rhomboid when viewed laterally, wider than petiole when viewed dorsally.

Erect and suberect hairs of various lengths covering all body surfaces; suberect hairs of various lengths present on mesosoma seen in profile.

Queen
Pacheco and Mackay (2013) - Measurements (n=1). TL 4.44; HL 0.660; HW 0.630; EL 0.252; ED 0.240; MOL 0.090; MOD 0.108; SL 0.480; FSL 0.240; CI 95.5; SI 72.7; PSL 0.080; PSW 0.070; PL 0.240; PW 0.300; PI 80.0; PPL 0.240; PPW 0.330; PPI 72.7; WL 0.960.

Concolorous pale yellow, moderately large; head subquadrate, slightly longer than wide, cephalic punctures coarse; clypeal anterior margin concave between lateral teeth, lateral teeth well developed, extralateral teeth bumps; clypeal carinae weakly developed; vertical striae on frontal lobes; eyes relatively large with approximately 150 ommatidia, eyes extend 0.060 mm past lateral margin of head; scape long, does not reach posterior lateral border of head; medial ocellus relatively large; propodeal margin with angular margin; propodeal spiracle relatively small; horizontal striae on metapleuron; petiolar and postpetiolar nodes similar in size when viewed laterally and dorsally, subpeduncular process with small tooth.

Abundantly hairy with hair of various lengths present on all body surfaces; approximately 35 erect and suberect hairs of various lengths present on mesosoma when viewed in profile; both petiole and postpetiole abundantly hairy with suberect hairs curved posteriorly.

Male
Pacheco and Mackay (2013) - Measurements (n=1). TL 3.00; HL 0.480; HW 0.480; EL 0.300; ED 0.240; MOL 0.096; MOD 0.150; SL 0.240; FSL 0.960; CI 100; SI 50.0; PSL 0.070; PSW 0.040; PL 0.240; PW 0.240; PI 100; PPL 0.240; PPW 0.300; PPI 80.0; WL 0.840.

Bicolored with brownish head and gaster, pale yellow body; head as long as wide; antennae pale yellow; eyes large, extend 0.720 mm past lateral margin of head; vertical striae between frontal lobes and anterior to medial ocellus, horizontal striae lateral to frontal lobes and eye; medial ocellus large; propodeal spiracle small; petiole wider than postpetiole in profile; small tooth present on subpeduncular process.

Abundantly hairy with erect and suberect hairs of various lengths present on all body surfaces; approximately 20 erect and suberect hairs of various lengths present on mesosoma when viewed in profile.

Type Material
Pacheco and Mackay (2013) - Pelee Island, Ontario, (holotype, winged queen from nest No. 1372, Kennedy collection, Ohio State University (OSUC), allotype a from nest No. 1372, ~ from nest No. 1372 (both seen OSUC), worker, described 1372, type rosea, C.H. Kennedy Collection, Barcode # OSUC 0119922 (seen OSUC), queen, rosea queen 1372, drawn, type rosea, C.H. Kennedy Collection, Barcode # OSUC 0119920 (seen OSUC), male, rosea male no. 1372, type rosea, C.H. Kennedy Collection, Barcode # OSUC 0119921 (seen OSUC). Pelee Island, Ontario, 1934, type nest 1372 (2 workers and 1 queen seen ).

References based on Global Ant Biodiversity Informatics

 * Kennedy C. H. 1938. Solenopsis rosella Kennedy, a new ant from southern Ontario. Can. Entomol. 70: 232-236.