Solenopsis quinquecuspis

Available records suggest that it is a common species in Uruguay and probably adjacent regions of southern Brazil and Argentina, that it often occurs sympatricly with other species in the saevissima complex, and that it often occurs on hilly or rocky ground. (Buren 1972)

Identification
Buren (1972) - A member of the Solenopsis saevissima species-group. The name of this species was badly chosen, as many of the major workers in the saevissima complex have five teeth on the clypeus-the two major teeth, a smaller tooth immediately laterad of each of these, and one small median tooth. The color is rather distinct, as this is one of the few species within the complex which lacks a spot or pale area on the first gastric segment. From Solenopsis richteri, quinquecuspis can be distinquished by the strongly convex promesonotum in profile in large workers, by the absence of a posteromedian sunken area on the pronotum, and by the strongly cordate head as well as the distinct color differences.

Pitts et. al. (2018) - The gynes of S. quinquecuspis are similar to the darker colored gynes of Solenopsis invicta. However, the OI of S. quinquecuspis is normally larger than that of S. invicta. The gynes of the darker varieties of Solenopsis richteri could be confused for S. quinquecuspis. In this case, the mesonotum of S. richteri is completely darkened and the mesonotal maculae are indiscernible. Also for S. richteri, the maculation on the first segment of the gaster covers the anterior 0.75 and it may end abruptly posteriorly. For S. quinquecuspis the maculation fades out gradually posteriorly. For S. quinquecuspis, this gaster maculation is only on the anterior 0.50 or less and is never distinctly margined posteriorly.

The male of S. quinquecuspis is dark in coloration and is similar to most of the other darker species. The pubescence is longer and denser than in Solenopsis saevissima. The S. quinquecuspis male normally is more coarsely sculptured than Solenopsis macdonaghi. The gena is not granulate nor is it as sculptured as in S. invicta. The larvae of S. quinquecuspis are distinct from the S. saevissima type by having simple setae on the head capsule.

The larvae of S. quinquecuspis are similar to S. macdonaghi and Solenopsis megergates. Although the body of S. quinquecuspis is larger and the setae on the body have a shorter base compared to S. macdonaghi, they are virtually indistinguishable. These larvae are much larger than the larvae of S. richteri (as expected given adult worker size), and lack multibranched setae and rugae on the head capsule.

Distribution
Pitts et. al. (2018) - The current range of S. quinquecuspis extends south from Rio Grande do Sul, Brazil through Uruguay and into Argentina. In Argentina, it occurs in Buenos Aires and La Pampa Provinces and the eastern edges of Santa Fe and Cordoba Provinces.

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

Biology
Pitts et. al. (2018) - Studies of nuclear and mtDNA genetic markers in S. quinquecuspis suggest that this species hybridizes with S. invicta and S. richteri in an area where the ranges of all three species overlap, in the vicinity of Rosario, Santa Fe Province, Argentina (Ross and Shoemaker 2005). In other areas of the range of S. quinquecuspis, there is no genetic evidence for such hybridization (Ross and Trager 1990).

Nomenclature

 *  quinquecuspis. Solenopsis pylades var. quinquecuspis Forel, 1913l: 224 (w.) ARGENTINA. Subspecies of saevissima: Santschi, 1916e: 379; Creighton, 1930b: 86. Junior synonym of richteri: Wilson, 1952b: 57. Revived from synonymy and raised to species: Buren, 1972: 17. Senior synonym of blumi: Trager, 1991: 185.
 * blumi. Solenopsis blumi Buren, 1972: 20, fig. 5 (w.) URUGUAY. Junior synonym of quinquecuspis: Trager, 1991: 185.

Worker
Buren (1972) - Head length .81 to 1.47 mm; width .66 to 1048 mm. In majors, head length 1.40 to 1.47mm, width 1.36 to 1.48 mm, scape length .97 to 1.06 mm, and thorax length 1.73 to 1.86 mm.

Head shape in large workers rather cordate in shape, with developed occipital lobes and rather strong occipital excision; always broader posteriorly except in small and sometimes in small medium workers. Scapes in full face view not meeting peaks of occipital lobes; in small workers slightly surpassing rear borders. Ocellar pit deep in large workers, but developed ocelli rare. From above pronotal shoulders moderately developed in large workers, smoothly rounded in medium and small workers. Promesonotal suture usually distinct medially in large workers, completely obliterated in medium and small workers. Pro-mesonotum in large workers strongly convex in profile, propodeum with longer base than declivity, base often straight, sometimes weakly convex, in either case at a different angle than the dorsum of the mesonotum. Seen from above, mesonotum nearly always of normal development, even in very large workers, propodeum usually without trace of longitudinal impression. Petiole with very thick, blunt scale, often subtruncate, sometimes with a weak notch posterodorsally. Postpetiole wider than long in large workers, with straight sides which may be slightly concave in medium and small workers. In a few very large workers the postpetiole may be wider in front than behind.

Genae with rough striae in front of eyes, these usually not extending far enough medially to meet with striae near antennal insertions. Punctostriae of meso- and metapleura very fine, often an area on lower mesopleura smooth and shining in large workers. Sides of petiole weakly punctate, front and rear faces smooth and shining. Sides of postpetiole partially or nearly completely covered with very fine, dense punctures. On posterodorsal face, front 1/3 or 1/2 smooth and shining or only weakly shagreened, rear 1/2 or 2/3 transversely punctostriate.

Pilosity of variegated pattern usual in saevissima complex; pilosity arising from moderately well developed punctures on head, many on both dorsal and ventral surfaces elongated shallowly. Pubescence sparse to moderate in density on front of petiole.

Concolorously piceous brown except for gaster which is a deeper, blackish brown. No trace of gastric spot; head colors, with minor exceptions, nearly uniform also.

Pitts et. al. (2018) - Head broad, cordate. Head sculpture with small piligerous foveolae, approximately 0.01 mm in diameter. Median frontal streak present, sometimes indistinct. Median ocellus in largest major workers present (absent in Fig). Mandibular costulae present throughout, sometimes obsolescent. Mesonotum with 20–25 setae. Promesonotal suture in largest major workers angulate medially, sometimes projecting upward. Mesonotum in lateral view weakly convex. Propodeum sculpture glabrous posteroventral to spiracle. Propodeum in largest major workers curves upward from metanotal groove higher than flattened posterior portion, appearing as anterior raised portion in lateral view. Postpetiole shape much broader than high. Postpetiole in posterior view with at least 0.75 transversely rugose to punctate-rugose, rugosity sometimes extending to dorsum. Color generally brown to dark brown on head, mesosoma, and median area of petiole. Gaster dark brown. Frons, clypeus, and T1 maculation brown orange.

Queen
Pitts et. al. (2018) - Head. Slightly broader than long, quadrate, sides of head convex from eyes to occipital angles, straight to nearly straight ventral to eyes. Eye sometimes with 3–12 setae protruding from between ommatidia, most setae ≤ 3X length of ommatidium, sometimes one or two ≤ 4X length of ommatidium. Median ocellus moderate, circular. Lateral ocelli slightly ovate, small to moderate. Clypeus projecting, carinal teeth stout and sharp, carinae indistinct between scrobes, slightly divergent ventrally. Paracarinal teeth small, usually well defined. Median clypeal tooth well developed. Approximately 0.50 of eye dorsal to midpoint of head.

Mesosoma. Parapsidal lines present on posterior 0.50 of disk. Mesonotum without posteromedian furrow. Bidentate medial process present on metasternum. Wing venation as in Fig.

Metasoma. Lateral faces of postpetiole weakly concave to weakly convex. Petiolar and postpetiolar spiracles slightly tuberculate in some cases.

Coloration, Sculpturing, and Pilosity. Piligerous foveolae small, sparse, width <0.01 mm in diameter, larger on head than on thorax and abdomen. Pubescence simple, pale brown to yellow and erect, longer and denser on head than elsewhere, longest on anterior edge of clypeus. Mesosoma with longest pubescence (length >0.30 mm) 2X longer than shortest pubescence. Mandible with 10–12 fine costulae. Propodeum with fine striae throughout. Posterior face of petiolar nodes with 0.75 of lower surface finely striatogranulate. Often, median striae of postpetiole obsolescent laterally; normally 11–13 striae present. Dorsum glabrous. Remaining integument smooth and polished. Color generally red brown. Venter of head, frons and coxae orange yellow. Gaster dark brown, sometimes orange anteriorly. T1 and S1 orange on basal 0.50 of disk, blending to red brown apically. Dark brown maculations present on mesonotum both anteromedially and on parapsidal lines. Median longitudinal maculation sometimes reaches scutellum. Internal margins of ocelli not brown. Median frontal streak present.

L ~7.1–7.7, HW 1.40–1.45, VW 0.81–0.95, HL 1.24–1.36, EL 0.40–0.44, OD 0.13–0.16, OOD 0.15–0.20, LOW 0.11–0.16, MOW 0.09–0.13, CD 0.17–0.20, MFC 0.15–0.23, EW 0.30–0.34, SL 0.94–1.01, PDL 0.17–0.19, LF1 0.08–0.11, LF2 0.07–0.10, LF3 0.06–0.09, WF1 0.06–0.07, FL 1.10–1.20, FW 0.26–0.31, MW 1.26–1.33, DLM 2.50–2.70, PRH 1.00–1.05, PL 0.65–0.72, PND 0.56–0.61, PH 0.66–0.75, PPL 0.25–0.34, DPW 0.50–0.71, PPW 0.60–0.74, PHB 0.36–0.44, N=7.

Male
Pitts et. al. (2018) - Head. Eye normally with 2–8 setae protruding from between ommatidia, setae length ≤3X length of ommatidium. Ocelli large and prominent, elliptical.

Mesosoma. Propodeum rounded, declivous face perpendicular, flat except with distinct to indistinct median longitudinal depression, basal face strongly convex transversely and longitudinally. Metapleuron broad, ~0.66 as wide as high. Wing venation as in Fig.

Metasoma. In cephalic view, dorsum of node with deep median impression, bilobate, sometimes lobes curve posteriorly. Petiolar spiracle distinctly tuberculate to not tuberculate. Postpetiolar spiracle distinctly tuberculate. Genitalia as in Figure.

Coloration, Sculpturing, and Pilosity. Pubescence short, yellow, erect to suberect (0.25–0.30 mm in length) on mesonotum. Mesonotal pubescence dense. Some shorter pubescence (0.15 mm in length) also on mesonotum. Pubescence longest on gena and vertex. Propodeum with base striato-granulate, medially coarsely granulate. Integument coarsely granulate on area between eye and insertion of antenna, area between ocelli, margins of metapleuron, and base of petiolar node. Vertex and, sometimes, gena striato-granulate. Head usually glabrous and shiny anteroventral to lateral ocelli. Head otherwise granulate. Pronotum granulate posteriorly. Mesonotum sometimes with coarsely granulate to striate margins. Posterior surface of postpetiolar node coarsely granulate throughout, sometimes rugose. Lateral faces of scutellum striate. Remaining integument smooth and polished. Color generally dark brown to black, legs brown. Antennal scape, pedicel and first flagellum brown, distal portion of flagellum blending to yellow apically. Mandibles yellow brown to brown.

L ~5.3–6.0, HW 1.02–1.10, VW 0.36–0.41, HL 0.77–0.82, EL 0.46–0.50, OD 0.09–0.12, OOD 0.14–0.23, LOW 0.10–0.14, MOW 0.11–0.14, CD 0.17–0.21, MFC 0.10–0.15, EW 0.32–0.37, SL 0.15–0.23, SW 0.07–0.12, PDL 0.05–0.08, PEW 0.11–0.16, LF1 0.15–0.22, LF2 0.10–0.17, LF3 0.15–0.19, WF1 0.09–0.12, FL 1.05–1.22, FW 0.16–0.21, MW 1.41–1.52, DLM 2.36–2.53, PRH 0.90–0.96, PL 0.64–0.67, PND 0.54–0.60, PH 0.25–0.28, PPL 0.24–0.35, DPW 0.50–0.62, PPW 0.61–0.70, PHB 0.20–0.28, N=8.

Larva
Pitts et. al. (2018) - Fourth instar worker larva.—Head. Large, subpyriform in anterior view (height 0.49 mm, width 0.55 mm). Cranium slightly broader than long. Antenna with 2 or 3 sensilla, each bearing spinule. Occipital setal row with 6–8 simple setae, 0.09–0.13 mm long; rarely some specimens with 1–2 denticulate setae. First setal row on vertex with 2 simple setae, 0.09–0.11 mm long. Second setal row on vertex with 4 simple setae, 0.12–0.13 mm long. Setae ventral to antenna level simple, 0.15–0.19 mm long. Clypeus with transverse row of 4 setae, inner setae shorter than outer setae, 0.06–0.11 mm long. Labrum small, short (breadth 2X length), slightly narrowed medially. Labrum with 4 sensilla and 2 setae on anterior surface of each half. Ventral border with 4–6 sensilla on each half. Each half of posterior surface of labrum with 2–3 isolated sensilla. Straight medial portion of mandible with 1–4 teeth that decrease in size dorsally. Maxilla with apex conical, palpus peg-like with 5 sensilla, each bearing one spinule. Galea conical with 2 apical sensilla, each bearing one spinule. Labium with patch of spinules dorsal to each palpus, in short rows of 2–3. Labial palpus slightly elevated with 5 sensilla, each bearing one spinule.

Body. Spiracles small, first spiracle larger than others. Body setae of 2 types. Simple setae (0.04–0.10 mm long) arranged in transverse row of 6–8 on ventral surface of each thoracic somite and on each of 3 anterior abdominal somites, some with short denticulate tips. Bifid setae (0.07–0.11 mm long) occur elsewhere, base 0.5X length, branches more or less perpendicular to base, tips recurved. Setae on thoracic dorsum with short base (<0.2X length).

Length. Approximately 3.8 mm.

Type Material
Pitts et. al. (2018) - Syntype workers. Argentina. Buenos Aires Province. Bahia Blanca. 28-X-913 (=1913). Zelenko. .

References based on Global Ant Biodiversity Informatics

 * Brandao, C.R.F. 1991. Adendos ao catalogo abreviado das formigas da regiao neotropical (Hymenoptera: Formicidae). Rev. Bras. Entomol. 35: 319-412.
 * Buren W. F. 1972. Revisionary studies on the taxonomy of the imported fire ants. Journal of the Georgia Entomological Society 7: 1-26.
 * Pitts J. P., G. P. Camacho, D. Gotzek, J. V. Mchugh, and K. G. Ross. 2018. Revision of the fire ants of the Solenopsis saevissima species-group (Hymenoptera: Formicidae). Proceedings of the Entomological Society of Washington 120(2): 308-411.
 * Trager J. C. 1991. A revision of the fire ants, Solenopsis geminata group (Hymenoptera: Formicidae: Myrmicinae). Journal of the New York Entomological Society 99: 141-198