Higher elevation coniferous forest species which occurs in moist habitats, in shaded grassy slopes with pines or grasslands. Temnothorax rugatulus can also be found in pinyon-juniper and cool desert habitats. Nests have been found in the soil, under rocks, in decaying wood, in grasses and in trees. Colonies may be monogynous, typically with a single macrogyne queen, or polygynous, with multiple microgyne queens. (Mackay 2000)
|At a Glance||• Facultatively polygynous • Tandem running|
- 1 Identification
- 2 Distribution
- 3 Biology
- 4 Castes
- 5 Nomenclature
- 6 References
Mackay (2000) - A member of the Temnothorax longispinosus species complex. Workers of this species have an 11 segmented antenna, a coarsely rugose dorsal surface of the head, the dorsum (and sides to a lesser extent) of the mesosoma and petiole are rugose as the head, the propodeal spines are well developed, longer than the distance between their bases, the dorsum of the postpetiole has rough punctures.
This species can be recognized by the coarse rugae on the head, the areas between the rugae are punctured, but shiny. This characteristic separates Temnothorax rugatulus from Temnothorax bradleyi and Temnothorax smithi. It is smaller than Temnothorax josephi and is basically concolorous medium yellowish-brown, often with dark infuscation on the head and mesosoma. The node of the petiole is rounded in profile, not truncate as in Temnothorax ambiguus. The subpetiolar process is often about as wide at the tip as it is at the base, although specimens that were previously referred to as Temnothorax rugatulus tend to have a tapered subpetiolar process. The propodeal spines are well developed which separates it from Temnothorax schaumii and Temnothorax whitfordi.
Keys including this Species
- Key to Temnothorax longispinosus species group workers
- Key to Temnothorax of California
- Key to the New World Temnothorax
Canada: British Colombia, Alberta.
United States: Washington, Oregon, Idaho, Montana, North Dakota, South Dakota, Wyoming, California, Nevada, Utah, Colorado, Arizona, New Mexico, Texas.
Mexico: Baja California.
Distribution based on Regional Taxon Lists
Distribution based on AntMaps
Distribution based on AntWeb specimens
Check data from AntWeb
High elevation coniferous forest, shaded grassy slopes with pines or grasslands, pinyon-juniper and cool desert habitats.
Nests often under rocks and in crevices on the underside of coarse rocks.
Cole (1934): This ant is rather frequent in moist habitats near Twin Falls, Hagerman and Buhl, chiefly along the Snake River. Colonies are small, the workers timid and sluggish and the brood scant. Winged forms appear at Twin Falls in late September.
Wheeler and Wheeler (1986): In Nevada Temnothorax rugatulus records are widely scattered, but absent from the southern quarter of the state. We have 30 records from 20 localities; 4,700-9,100 ft., mostly 6,000-7,000 ft. Fifteen records were from the Coniferous Forest Biome, 5 from the Pinyon-Juniper Biome, and 4 from the Cool Desert. Five nests were under stones, 8 were in rotten wood. This is a slow-moving ant.
Cole (1953, 1954): Colonies of Temnothorax rugatulus Emery were observed at an elevation of 6,350 ft. at Bandelier National Monument and 5 mi. E. of Taos, 7,350 ft. At both places nests were common beneath stones on shaded grassy slopes with pines. A number of the colonies was very populous and multiple queens were present.
An study of starvation resistance by Ruppel and Kirkman (2005) produced the following findings.
Most of a set of 21 laboratory colonies were able to survive eight months without any food. Brood decline began first (after two months) and mortality was highest, worker decline was intermediate, and queen mortality started latest and remained lowest. Brood (its relative change during the first four months and the level of brood relative to colony size) was the only significant predictor of colony starvation resistance.
Most colonies survived four months of total starvation without a significant decline. While it was found that the number of brood and workers was dramatically reduced after eight months, this time period exceeds the annual period of productive warm weather activity in most Temnothorax rugatulus habitats.
From this study they conclude that most well-fed colonies could survive a whole season without food. Internal resources and brood are suggested to be the only effective mediators of starvation resistance in this species. The amount of brood continued to increase during the first two months without food, with the brood then becoming a source of nutrients once internal reserves were depleted. Colony size was not shown to provide does not confer any survival advantage.
Colony size averaged from 54 to 141 workers (15 subpopulations), with a significant difference between pologyne (91±85 (SD)) and monogyne colonies (65±42). (Rüppell et al. 2001)
Moglich (1978) studying a population of Temnothorax rugatulus in a mixed oak-juniper forest in the Chiricahua Mountains found colonies had an average of 109 workers (range 30 to over 200).
Males fat stores were found to be 10.1±9.0 (SD) μg, n=40; macrogyne fat stores 466.4±146.9 μg, n=35; microgynes fat stores 51.4±12.3 μg, n=10. Relative fat content was not correlated with head width in microgynes (rp=–0.19, P=0.60), but was in macrogynes (rp=0.42, P=0.01).(Rüppell et al. 2001)
Nests have been found in the soil, under and between rocks, in decaying wood, in grasses and in trees. Colonies will readily emigrate to new nest locations if a nest or micro-ecological conditions become unfavorable.
Moglich (1978) studying a population of Temnothorax rugatulus in a mixed oak-juniper forest in the Chiricahua Mountains described their nests, which were found under stones. Dry brown oak leaves, juniper needles, little twigs and a diversity of other plant materials formed the bases of the nest chambers, which showed flat, often unbroken surfaces. Thus the whole colony was exposed after the stone was turned. The ants were crowded together either on the top of the material or upside down on the stone ceiling. Sometimes, however, a few small chambers were built into the base of the nest. Although the space covered by the rock measured 219 x 292 cm2 (range 32-1 800 cm2) the nest chambers were considerably smaller (24 x 17 cm2; range 2.4-63 cm2). The walls confining the nest chambers were constructed out of fine material like soil and small vegetation particles. Mean nest density was 1.5 ± 0.9 per 9.3 m2).
There are two queen morphs in Leptothorax rugatulus. Microgynes, slightly larger than worker size, and macrogynes, which are roughly twice as large as workers. Genetic evidence shows that queens in polygynous colonies are related to each other, supporting the hypothesis that colonies with more than one queen commonly arise by the adoption of daughter queens into their natal colonies. The higher fat content of macrogynes, their predominance in monogynous societies and in small founding colonies, and their greater flight activity favor the view that macrogynes predominantly found colonies independently, while microgynes are specialized for dependent colony founding by readoption. Despite the potential for these two mating strategies to lead to the creation of distinctive genetic subpopulations, genetic diversity is likely maintained by queens mating randomly with males. (Rüppell et al. 1998, Rüppell et al. 2001, Rüppell et al. 2003)
Temnothorax rugatulus use both tandem running and carrying behavior during nest emigration. Tandem running is strictly limited to the first phase of nest emigration, whereas carrying behavior is the predominant technique (84 %). Workers which are recruited by tandem running inspect the new nest site. If they accept it, they join the scout force and lead or carry nestmates to the new nest by themselves. (Moglich 1978)
Associations with other Organisms
Amecocerus sp. (Coleoptera: Melyridae; det. J.M. Kingsolver) was taken in a nest of Peavine Peak (Washoe Co.) at 6,800 ft. (Wheeler and Wheeler 1986)
Cysticercoids of a dilepidid cestode were found by dissection of aberrant yellowish workers and virgin queens of the ant Leptothorax rugatulus from several mountain ranges in the southwestern United States. The cestode was not positively identified, but cysticercoids are similar to those of the genus Anomotaenia previously found in related ants. (Heinze et al. 1998)
There are two queen forms, a microgyne and a macrogyne. Queens and males have been collected but have yet to be described.
The following information is derived from Barry Bolton's New General Catalogue, a catalogue of the world's ants.
- rugatulus. Leptothorax (Leptothorax) rugatulus Emery, 1895c: 321 (w.) U.S.A. Taber & Cokendolpher, 1988: 95 (k.). Combination in L. (Myrafant): Smith, M.R. 1950: 30; in Temnothorax: Bolton, 2003: 272. Subspecies of curvispinosus: Wheeler, W.M. 1903c: 241. Revived status as species: Wheeler, W.M. 1917a: 509. Senior synonym of annectens, cockerelli, mediorufus: Creighton, 1950a: 269; of brunnescens: Mackay, 2000: 394.
- annectens. Leptothorax curvispinosus subsp. annectens Wheeler, W.M. 1903c: 242, pl. 12, fig. 13 (w.) U.S.A. Subspecies of rugatulus: Wheeler, W.M. 1917a: 510. Junior synonym of rugatulus: Creighton, 1950a: 269.
- brunnescens. Leptothorax rugatulus subsp. brunnescens Wheeler, W.M. 1917a: 510 (w.) U.S.A. Wheeler, G.C. & Wheeler, J. 1955b: 25 (l.). Combination in L. (Myrafant): Wheeler, G.C. & Wheeler, J. 1955b: 25. Senior synonym of dakotensis: Creighton, 1950a: 269. Junior synonym of rugatulus: Mackay, 2000: 394.
- cockerelli. Leptothorax rugatulus var. cockerelli Wheeler, W.M. 1917a: 509 (w.q.) U.S.A. [First available use of Leptothorax curvispinosus subsp. rugatulus var. cockerelli Wheeler, W.M. 1903c: 241; unavailable name.] Junior synonym of rugatulus: Creighton, 1950a: 269.
- mediorufus. Leptothorax rugatulus var. mediorufus Wheeler, W.M. 1917a: 510 (w.q.) U.S.A. Junior synonym of rugatulus: Creighton, 1950a: 269.
- dakotensis. Leptothorax rugatulus subsp. dakotensis Wheeler, G.C. & Wheeler, E.W. 1944: 247 (w.) U.S.A. Junior synonym of brunnescens: Creighton, 1950a: 269.
The original description lists specimens from Colorado and South Dakota. Creighton (1950) gives the type locality as Colorado "by present restriction. Mackay 2000 - American Museum of Natural History, Museo Civico di Storia Naturale, Genoa Unless otherwise noted the text for the remainder of this section is reported from the publication that includes the original description.
Testacea, capite abdomineque magis minusve (uscatis, capite thoraceque dense punctatis et cum rugis subtilibus longitudinalibus,antennis 11 articulatis, thorace breviusculo, dorso haud impresso, spinis vix curvatis, obliquis, mediocribus, acutis; petioli segmento 1. postice modice incrassato, 2. subtrapezoideo, scapo pedibusque haud pilosis.
- n = 14 (USA) (Fischer, 1987) (as Leptothorax rugatulus).
- 2n = 26 (USA) (Taber & Cokendolpher, 1988) (as Leptothorax rugatulus).
- 2n = 27 (USA) (Taber & Cokendolpher, 1988) (as Leptothorax rugatulus).
Morphology, in reference to the rugosity found on the body.
- Bolton, B. 2003. Synopsis and Classification of Formicidae. Mem. Am. Entomol. Inst. 71: 370pp (page 272, Combination in Temnothorax)
- Cole, A. C., Jr. 1934. An annotated list of the ants of the Snake River Plains, Idaho (Hymenoptera: Formicidae). Psyche (Cambridge). 41:221-227.
- Cole, A. C., Jr. 1953. Notes on the genus Leptothorax in New Mexico and a description of a new species. Proceedings of the Entomological Society of Washington. 55:27-30.
- Cole, A. C., Jr. 1954. Studies of New Mexico ants. X. The genus Leptothorax (Hymenoptera: Formicidae). Journal of the Tennessee Academy of Science. 29:240-241.
- Creighton, W. S. 1950a. The ants of North America. Bull. Mus. Comp. Zool. 104: 1-585 (page 269, Senior synonym of annectens, cockerelli and mediorufus.)
- Emery, C. 1895. Beiträge zur Kenntniss der nordamerikanischen Ameisenfauna. (Schluss). Zoologische Jahrbücher, Abteilung für Systematik, Geographie und Biologie der Tiere. 8:257-360. (page 321, worker described)
- Heinze, J., O. Rüppell, S. Foitzik, and A. Buschinger. 1998. First records of Leptothorax rugatulus (Hymenoptera: Formicidae) with cysticercoids of tapeworms (Cestoda: Dilepididae) from the southwestern United States. Florida Entomologist. 81:122-125.
- Heinze, J., Rueppell, O. 2014. The frequency of multi-queen colonies increases with altitude in a Nearctic ant. Ecological Entomology (2014), 39, 527–529 DOI: 10.1111/een.12119.
- MacKay, W. P. 2000. A review of the New World ants of the subgenus Myrafant, (genus Leptothorax) (Hymenoptera: Formicidae). Sociobiology 36: 265-444 (page 394, Senior synonym of brunnescens)
- Mackay, W. P. and E. Mackay. 2002. The ants of New Mexico (Hymenoptera: Formicidae). Edwin Mellen Press, Lewiston, NY.
- Möglich, M. 1978. Social organization of nest emigration in Leptothorax (Hym., Form.). Insectes Sociaux. 25:205-225.
- Rüppell, O.; Heinze, J.; Hölldobler, B. 1998b. Size-dimorphism in the queens of the North American ant Leptothorax rugatulus (Emery). Insectes Soc. 45: 67-77 PDF
- Rüppell, O., J. Heinze, and B. Hölldobler. 2001. Alternative reproductive tactics in the queen size dimorphic ant Leptothorax rugatulus (Emery) and population genetic consequences. Behavioral Ecology and Sociobiology. 50:189-197.
- Rüppell, O. and R. W. Kirkman. 2005. Extraordinary starvation resistance in Temnothorax rugatulus (Hymenoptera, Formicidae) colonies: Demography and adaptive behavior. Insectes Sociaux. 52:282-290.
- Rüppell, O., M. Strätz, B. Baier, and J. Heinze. 2003. Mitochondrial markers in the ant Leptothorax rugatulus reveal the population genetic consequences of female philopatry at different hierarchical levels. Molecular Ecology. 12:795-801.
- Smith, M. R. 1950a. On the status of Leptothorax Mayr and some of its subgenera. Psyche (Camb.) 57: 29-30 (page 30, Combination in L. (Myrafant))
- Snelling, R.R., Borowiec, M.L. & Prebus, M.M. 2014. Studies on California ants: a review of the genus Temnothorax (Hymenoptera, Formicidae). ZooKeys 372, 27–89 (doi: 10.3897/zookeys.372.6039)
- Taber, S. W.; Cokendolpher, J. C. 1988. Karyotypes of a dozen ant species from the southwestern U.S.A. (Hymenoptera: Formicidae). Caryologia 41: 93-102 (page 95, karyotype described)
- Wheeler, W. M. 1903d. A revision of the North American ants of the genus Leptothorax Mayr. Proc. Acad. Nat. Sci. Phila. 55: 215-260 (page 241, Subspecies of curvispinosus)
- Wheeler, W. M. 1917a. The mountain ants of western North America. Proc. Am. Acad. Arts Sci. 52: 457-569 (page 509, Revived status as species)