Temnothorax rugatulus

(Emery, 1895)

Western Acorn Ant

Temnothorax rugatulus is a small to western North America, notable for its sophisticated collective decision-making behaviors and remarkable in size. The species exhibits two distinct queen : large macrogynes associated with single-queen (monogynous) colonies, and smaller microgynes found in multiple-queen (polygynous) colonies. This species has become an important model organism for studying , communication, and the molecular mechanisms underlying determination and phenotypic plasticity.

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Pronunciation

How to pronounce Temnothorax rugatulus: /tɛmnoʊˈθɔːræks ruːˈɡætjʊləs/

These audio files are automatically generated. While they are not always 100% accurate, they are a good starting point.

Identification

Distinguished from other Temnothorax by the presence of two (macrogynes and microgynes) within , associated with monogynous and polygynous colony structures respectively. are and small. Molecular and behavioral studies often required for definitive species identification within the . The species' western North distribution and forest help differentiate it from eastern .

Images

Appearance

are small, with uniform body size. occur in two distinct : macrogynes are approximately twice the size of workers, while microgynes are typically slightly smaller than workers. The lacks dramatic physical in the worker .

Habitat

Forests of the western United States, typically nesting in pre-existing cavities such as hollow acorns, twigs, or rock crevices. Colonies are cavity-nesting , utilizing small enclosed spaces with single entrance holes. spans montane and low-elevation forest , with monogynous colonies more common at lower elevations and polygynous colonies at higher elevations.

Distribution

Western North America including: western United States (extending from the Rocky Mountains westward, including North Dakota, South Dakota, and western Texas), Canadian provinces (Saskatchewan, Alberta, British Columbia, Yukon Territories), and northern Mexican states (Baja California, Sonora, Chihuahua).

Life Cycle

Colonies can be either monogynous (single ) or polygynous (multiple queens). Queen determines colony structure: macrogynes found in monogynous colonies, microgynes in polygynous colonies. Colony includes both and independent colony founding. exhibit reproductive plasticity: upon queen loss, workers can develop and become fertile, particularly in queenless conditions.

Behavior

Exhibits sophisticated collective decision-making using quorum sensing during nest site selection. Scouts evaluate potential nest sites and recruit nestmates through ; colonies prefer sites containing and show preference for darker nest sites. Uses multiple communication methods: tandem running (one-on-one guidance to targets), transportation (physical carrying), and reverse tandem running (guiding back to nest from outside locations). Produces context-dependent alarm signals using 2,5-dimethylpyrazine from —this compound attracts nestmates when released near the home nest but causes rejection of potential nest sites when encountered during . Demonstrates division of labor with distinct behavioral during emigrations: primary, secondary, passive, and wandering . Task switching incurs temporal delays. Workers show latitudinal variation in risk : northern colonies forage longer distances with less responsive but more aggressive threat response; southern colonies forage shorter distances with more responsive but less aggressive defense. Navigation relies primarily on visual cues including celestial orientation and landmark memorization; older workers depend more on visual cues while naive workers use trails. Exhibits starvation through brood protection using internal resources, reduced activity, and shorter foraging bouts; size may increase during starvation due to continued brood production.

Ecological Role

Subdominant in forest . Functions as a cavity-nesting that occupies small pre-existing . Serves as for specialized including the ponerine ant Thaumatomyrmex. Contributes to and soil through nest construction and foraging activities.

Human Relevance

Important model organism for research on , collective decision-making, communication systems, and the molecular mechanisms of determination and phenotypic plasticity. Studies on this have advanced understanding of quorum sensing, alarm signaling, division of labor, and epigenetic regulation of social traits.

Similar Taxa

Temnothorax curvispinosusEastern North with similar cavity-nesting ; distinguished by geographic range and lack of documented size
Temnothorax longispinosusEastern North used in evolution studies; differs in distribution and morphological patterns
Temnothorax pilagensSlave-making that raids Temnothorax ; distinguished by specialized predatory and smaller size

More Details

Queen Size Polymorphism and Social Structure

The association between and colony structure represents a rare example of intraspecific in social organization. Macrogynes are found in monogynous colonies at lower elevations, while microgynes occur in polygynous colonies at higher elevations. Brain transcriptomes show that the two morphs adjust differently to social environment, with influenced by the interaction between queen morph and social context rather than by either factor independently.

Molecular Mechanisms of Caste and Plasticity

T. rugatulus has been extensively studied for epigenetic regulation of social traits. Histone acetylation regulates and lifespan: removal triggers development and longevity extension in workers, but this is blocked by chemical inhibition of histone acetylation. Small profiles differ between and tissues: piRNAs show age- and caste-independent activity in germline protection, while miRNA expression varies with caste, , and age, suggesting miRNA-mediated regulation of caste-specific gene activity.

Research Methodology Notes

Studies on this have revealed important methodological considerations for behavioral research. Paint marking using CO2 anaesthetization does not affect exploratory and recruitment behaviors, validating common marking techniques. However, miniature tracking tag attachment reduces participation in tandem runs without affecting individual activity, demonstrating that tracking devices can negatively impact ant .