Solenopsis helena

Wheeler (1921) reported numerous specimens were collected from several colonies found in petioles of young Tachigalia along the Cuyuni trail at Kartabo, Guyana. He also stated that this species nests in hollow twigs of various other unspecified plants.

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 specimens (total length ~1.6 mm), but with the minor segments of the antenna being 0.12 mm in length. The head is relatively elongated, with the sides convex. The eye is small (0.045 mm maximum diameter) and apparently composed of 3-5 ommatidia. The propodeal spiracle is nearly the same width as the eye (maximum diameter 0.042 mm). The color ranges from pale brown to yellow. Queen - The queen is a moderately large, yellowish-brown specimen. The sides of the head are convex, the posterior margin is concave, the eyes are large (maximum diameter 0.180 mm), the scape nearly reaches the posterior margin (length 0.450 mm). The ocelli are small (maximum diameter of the median and lateral ocelli 0.060 mm), the distance between the median ocellus and the lateral ocellus is 0.070 mm. The propodeal spiracle is large at 0.102 mm in width. The petiole is narrow as seen in profile, with both the anterior and posterior faces being slightly concave.

Solenopsis helena could be easily confused with the widely distributed Solenopsis picea, but can be separated on the basis of color (much lighter in color than S. picea) and by having a smaller propodeal spiracle (propodeal spiracle of S. picea is larger in diameter than the diameter of the eye).

Distribution based on Regional Taxon Lists
Neotropical Region: Argentina, Brazil , Chile , Guyana , Panama, Paraguay.

Nomenclature

 *  helena. Solenopsis helena Emery, 1895i: 14, figs. (w.q.) CHILE. Senior synonym of schmalzi, schmalzi flaveolens, helena, hammeri, hammeri carhuensis, helena hermione, ultrix.
 * schmalzi. Solenopsis schmalzi Forel, 1901d: 297 (w.) BRAZIL. Junior synonym of helena: Pacheco & Mackay, 2013: 179.
 * flaveolens. Solenopsis schmalzi st. flaveolens Forel, 1901d: 298 (w.m.) BRAZIL. Santschi, 1923c: 255 (q.). Junior synonym of helena: Pacheco & Mackay, 2013: 179.
 * hammari. Solenopsis hammari Mayr, 1903: 400 (w.q.) BRAZIL. Junior synonym of helena: Pacheco & Mackay, 2013: 179.
 * carhuensis. Solenopsis hammari var. carhuensis Forel, 1912g: 8 (w.) ARGENTINA. Junior synonym of helena: Pacheco & Mackay, 2013: 179.
 * hermione. Solenopsis helena subsp. hermione Wheeler, W.M. 1921f: 157 (w.q.) GUYANA. Junior synonym of helena: Pacheco & Mackay, 2013: 179.
 * ultrix. Solenopsis helena subsp. ultrix Wheeler, W.M. 1921f: 157 (w.q.) GUYANA. Junior synonym of helena: Pacheco & Mackay, 2013: 179.

Worker
Extremement voisin de Solenopsis pollux Forel, dont il differe surtout par ses antennes plus longues et moins epaisses et la tete plus allongee, plus carree, a angles posterieurs moins arrondis et a bord posterieur plus sensiblement echancre. Le corselet est aussi un peu plus allonge, le 1er segment du pedicule proportionnellement plus grand lorsqu'on le regarde par cote. Son profil dorsal anterieur beaucoup moins concave; vu d'en haut, le 1er segment parait triangulaire, allonge, s'elargissant en arriere, le 2eme beaucoup plus court, nettement transverse, plus large que le rer. L'Insecte est aussi plus grand que S. pollux. Couleur jaune, et sculpture comme chez cette espece. Les figures me dispenseront d'une description plus detaillee de la forme du corps.

Long. 1 1/3 - 1 1/2 mm.

Pacheco and Mackay (2013) - Measurements (n=9). TL 1.44-1.68 (1.57); HL 0.402-0.462 (0.428); HW 0.348-0.402 (0.376); EL 0.030-0.048 (0.045); ED 0.024-0.036 (0.031); SL 0.288-0.372 (0.318); FSL 0.120-0.144 (0.129); CI 82.9-95.7 (88.9); SI 68.6-80.9 (74.2); PL 0.060-0.090 (0.079); PW 0.090-0.126 (0.109); PI 62.5-100 (73.4); PPL 0.072-0.150 (0.091); PPW 0.120-0.186 (0.145); PPI 54.2-80.7 (62.2); WL 0.300-0.390 (0.335); PSL 0.042; PSW 0.042.

Small; concolorous yellow; head longer than wide, sides convex, finely punctate; lateral clypeal teeth developed, extralateral teeth reduced to angles; scapes long, nearly reaching posterior lateral border of head, thin (0.036 mm at widest diameter); minor funicular segments 3-8 long; eye small, 3-5 ommatidia; pronotum finely punctate, smooth and shiny between punctures; mesopleuron smooth and shiny; notopropodeal suture well depressed, notch-shaped, groove breaks sculpture of mesosoma; propodeal spiracle large, nearly as large as eye; metapleuron horizontally striated; petiole wider than postpetiole when viewed laterally; anterior and posterior faces of petiolar node nearly straight, peduncle with small bump present ventrally; postpetiolar node thin, oval, lacking tooth or flange ventrally.

Abundantly hairy, pilosity yellow; erect and sub erect hair present on all body surfaces; head covered in erect and suberect hairs that protrude from small punctures; hairs on petiole and postpetiole curve posteriorly; gaster with abundant suberect hairs.

Queen
Ressemble egalement a S. pollux pour la taille et l'aspect general: couleur beaucoup plus claire, brun clair, avec les mandibules, antennes et pattes jaune testace. Les antennes sont bien plus longues, le scape depasse la moitie de l'espace qui separe l'ceil des angles posterieurs de la tete (il n'atteint pas la moitie de cet espace chez S. pollux). Les points piligeres sont moins nombreux sur la tete et le corselet. Les aretes laterales de la face declive du metanotum sont obtusement anguleuses. Le pedicule est conforme comme chez S. pollux, mais un peu moins robuste. Les ailes sont tout-a-fait hyalines, avec le point et les nervures tres pales (legerement enfumees, a nervures et point brun clair, chez S. pollux).

Taille un peu moindre que chez S. pollux: 3 - 3 1/4 mm. (sans l'abdomen 1 1/2 - 1 2/3).

Pacheco and Mackay (2013) - Measurements (n=l). TL 4.56; HL 0.660; HW 0.600; EL 0.234; ED 0.180; MOL 0.054; MOD 0.060; SL 0.450; FSL 0.240; CI 90.9; SI 68.2; PSL 0.102; PSW 0.102; PL 0.132; PW 0.252; PI 52.4; PPL 0.210; PPW 0.276; PPI 76.1; WL 1.02.

Moderately large; concolorous yellowish brown; head quadrate, longer than wide, sides convex, finely punctate; lateral clypeal teeth well developed, short, extralateral clypeal teeth represented by insignificant angles; eyes large; scape long, nearly reaches posterior margin; minor funicular segments 3-8 long; ocelli moderately small, distance between medial ocellus and lateral ocelli 0.070 mm; pronotum semi-coarsely punctate, smooth and shiny between punctures; mesopleuron smooth and shiny; posterior propodeal margin rounded; propodeal spiracle large, round; metapleuron horizontally striated; petiole narrow viewed laterally, with both anterior and posterior faces being slightly concave; postpetiolar node semicircular.

Abundantly hairy, pilosity yellow; erect and suberect hairs abundant on most surfaces, many hairs long (0.050-0.100 mm).

Type Information
Santa Rita, pres Santiago, 17 janvier 1895 (Santa Rita, near Santiago). Col. M. Lataste.

Pacheco and Mackay (2013) - Sta Rita 25, 17-i-95, Latasti Chili. Cantarera, b. Sao Paulo Coll. G. Mayr (lectotype worker, 3 paralectotype queens ). Solenopsis hammari carhuensis, Argentina, Buenos Aires, (Coll. A. Forel (There are four specimens mounted together, the third is the lectotype worker, the top two are paralectotype workers and the fourth is an arachnid ). Solenopsis helena hermione, Guiana, Kartabo (lectotype worker, 4 paralectotype workers and 1 paralectotype queen ). Solenopsis helena ultrix, Guiana, Kartabo, B.G. Jul, Aug. 1920, W.M. Wheeler Collection, M.C.Z. Cotype 23318, Typus 11 L (1 queen and 5 worker cotypes ).