Solenopsis pusillignis

Nothing is known about the biology of .

Identification
Pitts et. al. (2018) - A member of the Solenopsis saevissima species-group. The gynes and workers of S. pusillignis superficially look like small Solenopsis macdonaghi. This species is easily distinguished from S. macdonaghi and others, however, by having yellow workers with the posterodorsal and posteroventral area of the propodeal spiracle granulate, and by having the heads of the largest workers deeply emarginate. This species also has small gynes with small OOI measurements and large OI measurements and light-colored males with mesonotal maculae. The gynes of S. pusillignis differ from Solenopsis electra in coloration of the gaster (S. pusillignis has a lighter gaster and has a weakly developed T1 maculation), and S. pusillignis has a less developed median clypeal tooth.

The males of S. pusillignis normally have relatively large ocelli. This suggests that they may be nocturnally active.

The larvae of this species are also distinct in having more setae on the head capsule (10–12) than other species (normally 8 or less). Also, some have denticulate setae on the body, which differ from those found in some Solenopsis saevissima by being denticulate only at the extreme apex.

Distribution
Pitts et. al. (2018) -Currently, S. pusillignis is known from the type locality and the vicinity of Corumba, Mato Grosso do Sul, Brazil.

Distribution based on Regional Taxon Lists
Neotropical Region: Brazil.

Nomenclature

 *  pusillignis. Solenopsis pusillignis Trager, 1991: 194, figs. 40, 41, 44, 45, 84 (w.) BRAZIL.

Pitts et. al. (2018):

Worker
Head subovate to cordate. Head sculpture with small piligerous foveolae, <0.01 mm in diameter. Median frontal streak absent. Median ocellus in largest major workers absent. Mandibular costulae well developed throughout entire length at least medially. Mesonotum with 20–25 setae. Promesonotal suture in largest major workers gently curved medially, never projecting upward. Propodeum sculpture granulate posteroventral to spiracle. Postpetiole shape as high as or higher than broad. Postpetiole sculpture in posterior view with lower 0.75 transversely rugose, granulate, weakly granulate to glabrous and shiny. Color generally brown yellow to darker yellow brown with brown gaster.

Variation.—Trager (1991) considered this to be a small species, but also reported measurements from one series of specimens that he thought were atypically large. All of the newly collected colonies reported here have larger workers that fall into the atypical ranges noted in parenthesis by Trager (1991). Thus, this species is larger than first thought. In addition, some of the major workers have their heads deeply emarginate posteriorly, a distinctive feature that was not mentioned previously.

Queen
Head. Slightly broader than long, quadrate, sides of head convex from eyes to occipital angles, straight anterior to eyes. Eye sometimes with 6–10 long setae protruding from between ommatidia, setal length >4X length of ommatidia. Ocelli large, prominent. Median ocellus circular, lateral ocelli slightly ovate. Ocelli placed in more anterior position on head. Clypeus projecting, carinal teeth stout and sharp, carinae well defined, prominent between antennal scrobes, slightly divergent ventrally, edge of clypeus between carinae with shallow concave depression, depression deepest between carinal teeth. Paracarinal teeth small, 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 with median furrow on posterior 0.25. Metasternum with bidentate median process. Wing venation as in Fig.

Metasoma. Lateral faces of postpetiole weakly to strongly concave. In lateral view, petiolar node obtusely triangular, profile of peduncle flattened anteriorly, convex posteriorly. Postpetiole evenly convex. Postpetiolar spiracles weakly tuberculate.

Coloration, Sculpturing, and Pilosity. Piligerous foveolae small, sparse, width <0.01 mm in diameter, larger on head than on thorax and abdomen. Pubescence simple, golden and erect, longer and denser on head than elsewhere, longest on anterior edge of clypeus. Mesonotum pubescence 0.06–0.25 mm, longest pubescence on mesonotum 3–4X longer than shortest pubescence. Mandible with 9–11 fine, distinct costulae present throughout. Propodeum with fine striae throughout. Petiolar node basal 0.75 with striatogranulate, dorsum polished. Posterior face of postpetiolar node with lower 0.50–0.75 finely striate, lower 0.75 granulate, dorsum polished. Remaining integument smooth and polished. Color generally orange with mandibles and antennae orange brown, apical and lateral margins of metasoma segments 3–6 brown, and internal margins of ocelli dark brown.

L ~6.6, HW 1.20, VW 0.80, HL 1.14, EL 0.29, OD 0.12, OOD 0.16, LOW 0.11, MOW 0.13, CD 0.13, MFC 0.16, EW 0.28, SL 0.83, PDL 0.17, LF1 0.09, LF2 0.07, LF3 0.08, WF1 0.06, FL 0.96, FW 0.23, MW 1.25, DLM 2.20, PRH 0.43, PL 0.61, PND 0.51, PH 0.60, PPL 0.34, DPW 0.50, PPW 0.62, PHB 0.36, N=1.

Male
Head. Eye normally with 3–4 setae protruding from between ommatidia, setal length ≤ 3X width of ommatidium. Ocelli very 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 not broad, ;0.50 as wide as high. Wing venation as in Fig.

Metasoma. In cephalic view, dorsum of node with shallow median impression, weakly bilobate. Petiolar and postpetiolar spiracles distinctly tuberculate to not tuberculate. Genitalia as in Fig.

Coloration, Sculpturing, and Pilosity. Pubescence short (0.15–0.20 mm), dense, yellow, erect to suberect and of uniform length over mesonotum, longest on gena and vertex. Mesonotal pubescence sparse. Propodeum striato-granulate, medially finely granulate. Lateral faces of scutellum striato-granulate. Surface granulate in area between eye and insertion of antenna, posterior portion of metapleuron, and base of petiolar node. Posterior surface of postpetiolar node with lower 0.25 finely striato-granulate, sometimes with lower 0.50 finely striato-granulate but glabrous medially, dorsum polished. Area between ocelli rugose to granulate. Vertex glabrous posterior to ocelli. Several striae present anterior to occipital carina. Area posterior to eyes and antennal scrobes weakly granulate. Remaining integument smooth and polished. Head and gaster red brown. Clypeus, mandibles, petiole and postpetiole lighter yellow. Antennae and legs yellow. Mesosoma yellow to brown with median longitudinal stripe, area around parapsidal lines and scutellum red brown. Sometimes mesosoma yellow and parapsidal lines only slightly darker than surround integument.

L ~4.9–5.4, HW 0.95–1.0, VW 0.35–0.42, HL 0.74–0.80, EL 0.44–0.48, OD 0.10– 0.14, OOD 0.10–0.13, LOW 0.16–0.17, MOW 0.16–0.19, CD 0.10–0.12, MFC 0.33–0.36, EW 0.3–0.40, SL 0.14–0.18, SW 0.07–0.10, PDL 0.05–0.08, PEW 0.10–0.12, LF1 0.17–0.19, LF2 0.13–0.15, LF3 0.13–0.14, WF1 0.09–0.10, FL 0.98–1.05, FW 0.15–0.19, MW 1.20–1.30, DLM 2.15–2.30, PRH 0.80–0.88, PL 0.65–0.66, PND 0.58–0.61, PH 0.40–0.42, PPL 0.26–0.30, DPW 0.49–0.55, PPW 0.55–0.64, PHB 0.14–0.16, N=8.

Larva
Fourth instar worker larva.—Head. Large, subpyriform in anterior view (height 0.44 mm, length 0.44 mm) 190, 193). Cranium as broad as long. Antenna with 2 or 3 sensilla, each bears spinule. Occipital setal row with 10–12 bifid setae (less often 8), base ~0.3–0.5X total length of seta, setae 0.05–0.10 mm long. First setal row on vertex with 2 bifid setae, base ;0.5X total length of seta, ;0.07 mm long. Second setal row on vertex with 4 setae, inner 2 setae simple to denticulate, outer 2 setae bifid (base ~0.5X length), 0.08–0.11 mm long. Setae ventral to antenna level simple, 0.08–0.18 mm long. Clypeus with transverse row of 4 setae, inner setae shorter than outer setae, 0.08–0.11 mm long. Labrum small, short (breadth 2.4X length). Labrum with 5 minute sensilla and 2 setae on anterior surface of each half and ventral border with 4–6 sensilla on each half. Each half of posterior surface of labrum with 3–4 isolated and 2 contiguous sensilla. Straight medial portion of mandible with 2–5 teeth that decrease in size dorsally. Maxilla with apex conical, palpus peg-like with 5 sensilla, 1 bears spinule. Galea conical, smaller than maxillary palpus, with 2 apical sensilla, each bearing one spinule. Labium with patch of spinules dorsal to each palpus, spinules coarse and isolated or 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 (0.06–0.10 mm long) arranged in transverse row of 4–5 on ventral surface of each thoracic somite and on each of 3 anterior abdominal somites, some with short denticulate tips. Bifid setae (0.05–0.09 mm long) occur elsewhere, base varying between 0.2–0.5X length.

Length. 2.6–2.7 mm.

Type Material
Holotype worker. Brazil. Mato Grosso State. Cuiaba. Trager. . (Holotype was unavailable for study.)

References based on Global Ant Biodiversity Informatics

 * 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