Temnothorax curvispinosus

This is one of North America's better studied ant species. Many aspects of their basic biology has been examined and a variety of experiments have studied particulars about their nesting behavior, foraging and social dynamics.

Identification
Mackay (2000) - A member of the Temnothorax schaumii species complex. This is a small yellow ant with an 11-segmented antenna, which is very common in eastern USA. The very long, inwardly curved, closely spaced propodeal spines make this species immediately recognizable. The top and side of the mesosoma are covered with coarse rugae. The head is completely and coarsely punctate.

Distribution
USA. Throughout the eastern United States, from Maine to central Florida, and westward through eastern North Dakota down through the eastern half of Texas.

Distribution based on Regional Taxon Lists
Nearctic Region: United States.

Habitat
Forest.

Abundance
Common.

Biology
The following summary is from Mackay (2000): "The habits of this species are well known (Wheeler, 1916, 1917; Smith, 1924; Dennis, 1938; Cole, 1940; Wesson and Wesson, 1940; Headley. 1943; Buren, 1944; Gregg, 1944; Talbot. 1934, 1957, 1965; DuBoiS, 1985). Nests are found in plant cavities including hollow stems, under bark of living trees, in reeds, twigs, logs, acorns, nut shells, insect galls, puffballs, pine cones (Williams, 1989) and under rocks or in soil in forested areas (Wheeler, 1903a, 1905; Cole, 1940; DuBoiS. 1985). It is found at lower elevations in the southern Blue Ridge of Virginia (Van Pelt, 1963). Nest populations are about 80-100 workers with several queens (Wilson, 1974a), up to 113 workers in acorn nests (Talbot. 1957); average populations in Ohio were 235 (all castes), with the largest population of workers being 369 (total members 727), and nest densities of 0.6 nests per square meter (Headley, 1943). Alates are present from June-Aug. (Kannowski, 1959; Talbot, 1957; DuBoiS, 1985); flights occur in early July (Wesson and Wesson 1940). Workers reproduce in queenright colonies (Frumhoff and Ward. 1992). Larvae are found within nests throughout the year (Headley. 1943; Talbot. 1957). Nests are polygynous (Alloway et al.. 1982) and polydomous (Stuart. 1985, 1987a). The nest site may change after slight disturbances (Moeglich. 1978). The species is widely distributed in many different habitats, and is especially common in Tennessee (Dennis. 1938), Ohio (Wesson and Wesson. 1940), near Chicago (Gregg. 1944) and Mississippi (Smith. 1924). Herbers (1983) discussed the social organization and Wilson and Fagen (1974) estimated the total behavioral repertories. Stuart (1987a. 1987b) reported on transient nestmate recognition. Wilson (197 4b) studied the behavior of workers in laboratory colonies. It eats honeydew on leaves of trees and plants (Smith. 1924), but apparently does not tend aphids (Dennis,1938), and carries seeds (Heithaus. 1981) and presumably eats at least part of them. They also feed at the axillary nectaries of bracken fern (Douglas. 1983), and on dead insects (Fellers and Fellers. 1982). Foraging involves tandem running (Moeguch. 1979). Seasonally, foraging rate is highest in the spring and early summer, dropping off in the fall and being absent in the winter (Fellers. 1989). It is most active during the daylight hours (Fellers. 1989).

It is the host of Temnothorax duloticus (Talbot. 1957), Temnothorax americanus (Emery. 1895; Alloway et al.. 1982; Alloway and del Rio Pesado. 1979. 1983; pers. obs.), possibly T. minutissimus (Smith. 1942) and Limulodes parki (Coleoptera-Seevers and Dybas. 1943)."

Colony Attributes
Colonies typically contain less than one hundred workers although an occasional nest can be found that exceeds this number. Roughly half of the queens survive the winter, for workers roughly two thirds to slightly more than one half survive from fall to spring.

Nests are located in preformed cavities in structures found in the litter, e.g., in small sticks or nuts. Temnothorax curvispinosus is facultatively polydomous and their nesting arrangements vary with season. In the productive summer months, colonies can fragment and be arranged across numerous nest sites. These vary in queen number, from multiple queens to those that only have workers and brood.

During the winter nests coalesce and typically are found in a single structure. In the northeastern hardwoods forests this will typically be a nut (acorn, hickory) or small twig in the leaf litter. Nest mortality can be significant. From one third to one half of all nests are gone by the end of the winter. Some of these losses are colony deaths while others represent migration to a new nest site, which likely occurs during warmer winter days.

Nests of T. curvispinosus were found by Gibson et al. (2019) in bird nests.

MacGown (2006) examined ants nesting or occupying hickory nuts in the Tombigbee National Forest (Ackerman Unit), Mississippi. While several hickory species were present, ants were found almost exclusively in the nuts of Carya glabra. Nine colonies of Temnothorax curvispinosus were found, with 254 workers and 1 queen, 150 workers and 1 queen, 97 workers and 1 queen, 87 workers and 1 queen, 84 workers and 1 queen, 73 workers and 1 queen, 65 workers and 1 queen, 36 workers and 1 queen and 35 workers and 1 queen. These colonies fall within the size range of those observed by Headley (1943) in acorns. This is not surprising as Carya glabra hickory nuts are approximately the same size as many species of acorns, especially those of Quercus alba, which Headley mostly searched. It has been shown in laboratory tests that T. curvispinosus select larger cavities when given a choice and that they prefer a compact, high-ceilinged cavity over a thin, flat crevice, even if of equal volume (Pratt and Pierce, 2001). Combining this preference with the fact that the nuts of C. glabra have an extremely strong outer shell, it is clear that nuts and acorns provide a suitable and desirable shelter in all seasons for these ants. It also explains why T. curvispinosus colonies were found with relative ease and in large numbers in the hickory nuts while the species was otherwise only rarely encountered in the Tombigbee National Forest when using pitfall and other collecting methods (MacGown, 2006).

Reproduction
Queen number can vary by colony and season. New colonies are founded by pleoemetrosis and new queens are likely adopted into existing nests. The latter is evident from the presence within populations of both monogynous and polygonous nests. Reproductive queens contain 8 ovarioles.

Worker reproduction does occur with some male production possible from worker derived eggs. Reproductive workers contain 2 ovarioles.

New queens are produced in some queenless nests. These are presumed to be nests that are separated from a queenright nests or from a nest that had earlier lost its queen(s).

Kannowski (1959) noted the following concerning Temnothorax ambiguus reproduction in southeastern Michigan: "Alates were found in nests in bog communities from July 7 to August 6. In upland forest communities on the George Reserve, where curvispinosus is common, Talbot (1957, p. 451) found that alates were present in nests from late June to early August.

Other Ants
This species is parasitized by the slave-making ants and  and the workerless inquiline  (Beibl et al. 2005).

Nomenclature

 *  curvispinosus. Leptothorax curvispinosus Mayr, 1866a: 508, pl., fig. 13 (w.) U.S.A. Mayr, 1886d: 451 (q.); Mackay, 2000: 338 (m.). Combination in L. (Myrafant): Smith, M.R. 1950: 30; in Temnothorax: Bolton, 2003: 271. Senior synonym of gallarum: Mayr, 1886d: 453. See also: Wheeler, W.M. 1903c: 239; Mackay, 2000: 337.
 * gallarum. Stenamma gallarum Patton, 1879: 126 (footnote) (w.q.) U.S.A. Junior synonym of curvispinosus: Mayr, 1886d: 453.

Type Material
North America. As reported in Mackay (2000): One cotype worker in [seen]. specimens could not be located in Roger's collection (Museum fur Naturkunde Zentralinstitut der Humboldt-Universitat zu Berlin).

Worker
Operada: Long. 2.4mm Flava, capite rubescente-flavo, abdominis segmento basali postice fascia fusescenti medio interrupta; caput, thorax, petiolus et abdomen pilis subclavatis erectis. scapus pilis simplicibus paulo abstantibus, pedes sine pilis abstantibus; mandibulae subtiliter striolatae; clypeus longitudinaliter striatus, medio non impressus et inermis; caput dense reticulato-punctulatus, fronte distincte, vertice antice indistincte subtiliter et longitudinaliter rugulosis; antennae 11articulatae; thorax longitrorsum convexus, sine impressione transversa,subtiliter et longitudinaliter rugulosus et partim reticulato-punctatus; metanotum spinis duabus longis, paulo curvatis, parte metanoti basali sublongioribus, inter spinas transverse rugosum; petioli nodi,reticulato-punctati; abdomen laevissimum et nitidum.

Queen
Mayr (1886d) Weibchen. Lange: 3-3·3mm. Rothlichgelb oder gelbroth, die Oberkiefer, Fiihler und Beille mehr gelb, del' Kopf mehr oder weniger gebraunt, ein Fleck in del' Mitte des Mesonotum, das Scutellum, a,uch theilweise das Metanotum,dann del' Petiolus ganz oder theilweise und oft auch die Seiten des Thorax lichtbraun, der Hinterleib schwarzbraun, die Vorderhalfte des ersten Abdominalsegmentes gelb. Die Behaarung wie beim Arbeiter. Die Oberkiefer langsgestreift und fiinfzahnig. Del' Kopf ist langsgerunzelt, die Fiihlergruben sind fein genetzt, del' Clypeus massig convex, die Fiihler eilfgliedl'ig. Das Pronotum ist streifig-gerunzelt, hie und da sind die Runzeln mitsammell netzartig verbnnden, zwischen den Runzeln fein genetzt; das Mesonotum ist langsgestreift,das Scutellum langsgerunzelt; das Metanotum mit zwei ziemlich starkell, kaum gekriimmten parallelen Dornen, welche, innen gemessen, etwas kiirzer sind, als ihre Spitzen von einander entfernt sind; zwischen den Dornen ist das Metanotum quergerunzelt oder genetzt, aussen ist es langsgerunzelt und fein genetzt. Del' Hinterleib ist glatt und glanzend.

Male
Mackay (2000): Mandible with apical and 1 or 2 subapical teeth well defined, others present as denticles; median anterior border of clypeus weakly convex. clypeus with well defined central, longitudinal carina and a few other, poorly defined lateral carinae; eyes very large, occupying most of side of head; ocelli well developed, diameters of all three greater than distance between them; scape short, extending about half distance to occipital corner; propodeal spines or angles absent, only indication is a poorly defined carina; petiole with low node, which is not much higher than peduncle.

Hairs erect and scattered on most surfaces, suberect on antennae and legs; decumbent pubescence sparse.

Sculpture consisting of rough, longitudinal striae on most of head, area posterior to eyes with concentric whorls, clypeus with central carina and poorly defined lateral carinae, sides of mesosoma mostly smooth and shining, but with a few rugae, propodeum mostly smooth, but finally striate, petiole striate.

Color: pale yellow with black eyes.

Male measurements: HL 0.52-0.53, HW 0.47-0.50, SL 0.17-0.20, EL 0.25-0.26, WL 0.97-1.02. PW 0.10-0. 14, PL 0.08-0.23, PPW 0.18-0.19, PPL 0.22. Indices: CI 90-94, SI 33-38, PI 61-125, PPI 82.

Etymology
Morphological. A reference to the inwardly curving propodeal spines of the workers.