We present an overview of the known ant fauna of Alberta, Canada, which consists of 94 species and subspecies in 16 genera and three subfamilies. Two potentially new species were identified in the genus Myrmica, while the rest of the fauna is represented by previously recognized taxa. We provide an illustrated HTML-based dichotomous key to species of ants in Alberta based mostly on morphological characters of the worker class. When keyed to a species, a hyperlink to its species profile on www.antweb.org is provided for photographic and locality comparison.

Lasius pallitarsis - Photo by Heather Proctor

Worldwide, ants (Hymenoptera: Formicidae) are recognized as important ecosystem engineers that affect nutrient cycling, soil structure, seed dispersal, and the populations of many other invertebrates (Briese 1982; Hölldobler and Wilson 1990; Jones et al. 1994; Folgarait 1998). From an anthropocentric point of view, many ants are considered pests because of their abilities to disrupt lawns and infest homes, and their habit of viciously defending their colonies through biting and stinging (Klotz et al. 2008). Although ants are widespread and abundant throughout Alberta, little is known about their ecology or diversity in the province.

The study of Alberta’s ant fauna began with Sharplin (1966), who assembled an annotated list of 40 species known to occur in the province. Sharplin built on the faunistic and revisionary works of such American workers as Wheeler (1905, 1913), Creighton (1950), Wilson (1955), and Wheeler and Wheeler (1963). Since then, a number of new species have been described from Alberta (Buschinger 1979, 1983; Heinze 1989; Mackay and Buschinger 2002; Buschinger and Schultz 2008), five genera with representatives in Alberta have been partly or entirely revised or reviewed (Francour 1973 for Formica; Francour and Buschinger 1985 for Formicoxenus; Mackay 1993 for Dolichoderus; Mackay 2000 for Temnothorax; Hansen and Klotz 2005 for Camponotus), the faunas of a number of relevant regions have received treatments (Gregg 1972; Yensen et al. 1977; Wheeler and Wheeler 1986; 1988, 1997; Naumann et al. 1999; Mackay and Mackay 2002; Heron 2005; Clark and Blom 2007), and a few ecological studies have focused on Albertan ants (e.g. Wu and Wong 1987; Savolainen and Deslippe 2001; Perry 2004; Newton et al. 2011). In addition, a number of overarching treatments have been published that deal with ants globally (Hölldobler and Wilson 1990; Bolton 1994, 1995), in North America (Fisher and Cover 2007), or in urban environments in North America and Europe (Klotz et al. 2008). Work in Alberta over the past 45 years, and especially the recent field studies of Glasier (2012), have more than doubled the number of species known from the province, making it worthwhile to provide a key to this ecologically important fauna.  The key was initially based on a variety of existing publications (Creighton 1950; Wilson 1955; Wheeler and Wheeler 1963; Francoeur 1973; Francoeur and Buschinger 1985; Wheeler and Wheeler 1986; Mackay and Mackay 2002; Hansen and Klotz 2005), and modified for Alberta, based on our experience with the fauna.

Ants were collected at a variety of sites around Alberta. Large numbers were examined from areas associated with three ecological studies: the EMEND forestry project in the Peace River area of northwestern Alberta (http://www.emend.rr.ualberta.ca), Glasier’s studies of ants on central Albertan sand hills (summarized in Glasier 2012), and a study by Newton et al. (2011) on native fescue grassland from east-central Alberta. In addition, collections were examined at the Royal Alberta Museum, the University of Calgary Entomological Collection, and the E. H. Strickland Entomological Museum at the University of Alberta. Vouchers of each species collected will be deposited in the E. H. Strickland collection, and additional specimens have been retained in the personal collection of James Glasier.

Overview of the Fauna
Based on published records and the collections described above, there are 93 species (one of which includes two named subspecies) in 16 genera and three subfamilies known from Alberta (Table 1 and Figures 4-94).  By far the most species-rich genus is Formica, with 38 recorded species. Other species-rich genera include Camponotus, Lasius, Myrmica, and Leptothorax. Several rare or geographically restricted genera include Dolichoderus, Solenopsis, Manica, and Pogonomyrmex. There are four putatively endemic species in Alberta: Leptothorax athabasca Buschinger and Schulz, Leptothorax pochahontas (Buschinger), Leptothorax faberi Buschinger, and Temnothorax fragosus (Mackay and Buschinger), all apparently restricted to the Rocky Mountains. Of the 93 species of ants in Alberta, 91 are indigenous and two, Monomorium pharaonis (Linnaeus) and Brachymyrmex obscurior Forel, are introduced and are almost solely found within human buildings (Klotz et al. 2008).

Taxonomic Issues
Several genera likely contain more species in Alberta than are listed. Some may be undescribed, while others are simply difficult to distinguish and are thus not yet confirmed for the province. These issues are briefly summarized here.

Leptothorax: Leptothorax species are difficult to identify confidently, as the diagnostic characteristics for many species are poorly defined (Fischer and Cover 2007; Buschinger and Schultz 2008). Even among the species we chose to recognize here, many individuals will be difficult to place correctly. In addition, the taxon we refer to as Leptothorax muscorum (= “L. canadensis" (Nylander), a name proposed for North American members of this Holarctic taxon) may represent several species in Alberta, including L. pocahontas.

Temnothorax: like Leptothorax, Temnothorax from the northern Nearctic is relatively poorly known (Mackay and Buschinger 2002; Buschinger and Schultz 2008). It is possible there are more species waiting to be recognized in Alberta.

Myrmica: this genus contains several species that are morphologically similar (Fischer and Cover 2007). It is probable that because of limited taxonomic work, and limited collecting, more species exist in Alberta. Two potentially new species (referred to here as Myrmica ab01and Myrmica code AF-eva), are morphologically distinct from known species, and were included in the key as tentatively different until further descriptions can be made. Myrmica ab01 is similar to Myrmica crassirugis but possesses distinctly upturned propodeal spines. Myrmica code AF-eva is similar to Myrmica americana, but possesses smaller lamina on the basal bend of its scape. As the North American Myrmica are currently being revised by Dr. André Francoeur, at University of Quebec (personal communication), these potentially new species may be described by him.

Formica: the genus Formica contains six species groups and numerous species that are difficult to separate from one another (Fisher and Cover 2007). Traits that cannot be seen without a high resolution dissecting microscope, regional variation within species, and differences relying on subtle characters based on setae and/or pubescence often make Formica difficult to identify to species with any confidence. In this key we try to simplify these difficulties, but comparison with identified material, and familiarisation by working with large numbers of specimens is the best way to see the differences present between similar species of this genus. We recognize a difference between subspecies F. oreas oreas and F. oreas comptula; however, more work is needed before determining if they are conspecific, are indeed subspecies, or deserve further taxonomic separation. In addition some specialists informally suspect that F. obscuripes and F. planipilis may hybridize or be conspecific, though we chose to keep them separate for this key as they are well established in the literature (Creighton 1950; Wheeler and Wheeler 1963; Wheeler and Wheeler 1986; Mackay and Mackay 2002).

Preparing Specimens for Use with this Key
The key is intended to allow identification of worker-caste ant specimens from Alberta, but careful specimen preparation will facilitate identification. The following tips should ensure that adequate material is acquired at the time of collection. A stereo microscope with at least 50X magnification is required to see many of the characteristics mentioned in the key, and careful experimentation with lighting, including diffusion, may be required as well.

• Collect a range of worker sizes and multiple specimens (minimum of five recommended).
• Specimens in ethanol can be difficult to identify. It is best for the specimens to be pinned, pointed (glued to a triangular card) and dry, so that structures such as erect setae are easier to see.
• When pointing specimens make sure the mandibles are open so you can see all mandibular teeth. For the genera Lasius, Temnothorax and Leptothorax this is particularly important.
• For identification of Camponotus species, major workers are required (Hansen and Klotz 2005); however it is important to collect all castes, especially when dealing with arboreal species such as Camponotus nearcticus,whose majors can easily be confused with minors from larger Camponotus species.
• For identification of Formica fusca group specimens there is a couplet in the key where some dissection is needed. This dissection is best done before the specimen is pointed. Remove the posterior four legs including the coxae, and then mount the specimen on its side; this will allow for structures required for identification to be seen.
• For identification of Lasius, workers of several species are very similar (especially in the subgenus Acanthomyops). Characters of many of these species are most evident and less variable in the larger workers (Wilson 1955; Mackay and Mackay 2002), especially for mandibular tooth characters; therefore smaller specimens of a species can easily be confused.  To alleviate any confusion it is best to examine multiple specimens from a colony.
• For identification of Myrmica species, when using antennal characters it is best to orient the antenna as pictured in Figs. 14a and 14b.  The base of the scape should be oriented perpendicular to the head so as to reveal laminal characters in posterior and anterior views.

Table 1. List of species of Formicidae known from Alberta:

Asterisks (*) indicate ant species that have been reported from Alberta in the literature, but have not been encountered by the authors.

Subfamily Dolichoderinae
Genus Dolichoderus
            Dolichoderus taschenbergi (Mayr) 1866
Genus Tapinoma
            Tapinoma sessile (Say) 1836

Subfamily Formicinae
Genus Brachymyrmex
            Brachymyrmex depilis Emery 1893
            Brachymyrmex obscurior Forel 1893
Genus Camponotus
            Camponotus herculeanus (Linnaeus) 1758
            Camponotus laevigatus (Smith) 1858 (Hansen and Klotz 2005*)
            Camponotus modoc Wheeler 1910
            Camponotus nearcticus Emery1893
            Camponotus novaeboracensis (Fitch) 1855
            Camponotus vicinus Mayr 1870
Genus Formica
            Formica accreta Francoeur 1973
            Formica adamsi Wheeler 1909
            Formica altipetens Wheeler 1913
            Formica argentea Wheeler 1902
            Formica aserva Forel 1901
            Formica bradleyi Wheeler1913
            Formica canadensis Santschi 1914
            Formica dakotensis Emery 1893
            Formica densiventris Viereck 1903
            Formica emeryi Krausse1926
            Formica fossaceps Buren 1942
            Formica fusca Linnaeus 1758
            Formica glacialis Wheeler 1908
            Formica hewitti Wheeler 1917
            Formica impexa Wheeler 1905
            Formica integroides Wheeler 1913
            Formica lasioides Emery 1893
            Formica limata Wheeler 1913
            Formica microgyna Wheeler 1903
            Formica montana Wheeler 1910
            Formica neoclara Emery 1893
            Formica neogagates Viereck 1903
            Formica neorufibarbis Emery 1893
            Formica obscuripes Forel 1886
            Formica obscuriventris Mayr 1870
            Formica obtusopilosa Emery 1893
            Formica opaciventris Emery 1893
            Formica oreas Wheeler 1903
            Formica oreas comptula Wheeler 1913
            Formica perpilosa Wheeler 1913
            Formica planipilis Creighton 1940
            Formica podzolica Francoeur 1973
            Formica puberula Emery 1893
            Formica ravida Creighton 1940
            Formica rubicunda Emery 1893
            Formica subintegra Wheeler 1908
            Formica subnitens Creighton 1940
            Formica subpolita Mayr 1886
            Formica ulkei Emery 1893
Genus Lasius
            Lasius alienus (Förster) 1850
            Lasius coloradensis Wheeler 1917
            Lasius crypticus Wilson 1955
            Lasius fallax Wilson 1955
            Lasius flavus (Fabricius) 1781
            Lasius latipes (Walsh) 1863
            Lasius neoniger Emery 1893
            Lasius niger (Linnaeus) 1758
            Lasius pallitarsis (Provancher) 1881
            Lasius subglaber Emery 1893
            Lasius subumbratus Viereck 1903
            Lasius umbratus (Nylander) 1846
Genus Polyergus
            Polyergus breviceps Emery 1893

Subfamily Myrmecinae
Genus Formicoxenus
            Formicoxenus hirticornis (Emery) 1895
            Formicoxenus provancheri (Emery) 1895
            Formicoxenus quebecensis Francoeur 1985
Genus Harpagoxenus
            Harpagoxenus canadensis Smith 1939
Genus Leptothorax
            Leptothorax athabasca Buschinger and Schultz 2008
            Leptothorax faberi Buschinger 1983 (Buschinger 1983*)
            Leptothorax muscorum (Nylander) 1846
            Leptothorax pocahontas (Buschinger) 1979 (Buschinger 1979*)
            Leptothorax retractus Francoeur 1986
            Leptothorax wilsoni Heinze 1989 (Heinze et al. 1995*)
Genus Manica
            Manica hunteri (Wheeler) 1914
            Manica invidia Bolton* 1895 (Sharplin 1966)
Genus Monomorium
            Monomorium minimum (Buckley) 1867
            Monomorium pharaonis (Linnaeus) 1758
Genus Myrmica
            Myrmica ab01(near Myrmica crassirugis)
            Myrmica code AF-eva (near Myrmica americana)
            Myrmica alaskensis Wheeler 1917
            Myrmica americana Weber 1939
            Myrmica brevispinosa Wheeler 1917
            Myrmica crassirugis Francoeur 2007
            Myrmica detritinodis Emery 1921
            Myrmica fracticornis Forel 1901
            Myrmica incompleta Provancher 1881
            Myrmica latifrons Stärcke 1927
            Myrmica lobifrons Pergande 1900
            Myrmica nearctica Weber 1939
Genus Pogonomyrmex
            Pogonomyrmex occidentalis (Cresson) 1865
            Pogonomyrmex salinus Olsen 1934
Genus Solenopsis
            Solenopsis molesta (Say) 1836
Genus Temnothorax
            Temnothorax ambiguus (Emery) 1895
            Temnothorax fragosus (Mackay and Buschinger) 2002
            Temnothorax rugatulus (Emery) 1895

Some of the terms used in ant identification may be unfamiliar, even to those who work on other insect groups. Definitions for this glossary are based on a variety of existing definitions from a wide range of entomological sources (Torre-Bueno et al. 1989; Hölldobler and Wilson 1990; Bolton 1994; Mackay and Mackay 2002; Fisher and Cover 2007). Terms used in the key are defined below.

Antenna: paired, segmented sensory appendages attached to the front of the head.

Antennal fossa: depressed area around the antennal socket.

Antennal socket: articulation of the antenna with the head.

Apex: tip, most distal point (plural= apices).

Apical club: antennae have an apical club when the distal (terminal) segments are enlarged relative to more basal segments.

Appressed setae: setae that lie against, or run almost parallel to, the cuticle of an ant.

Basal tooth: the basalmost tooth along the chewing margin of the mandible, closest to the anterior margin of the clypeus.

Carinate: having multiple carinae (ridges).

Clavate setae: setae that are expanded at their apices.

Clypeus: the anterior median sclerite of an ant head. The anterior margin of the clypeus forms the anterior margin of the head in frontal view.

Clypeal fossa: depression near the posterior margin of the clypeus, formed from the lateral “wings” or sides of the clypeus.

Concolourous: head, mesosoma and gaster are all the same colour.

Decumbent setae: setae that stand at an angle of between 10-40 degrees from the cuticle of ant.

Erect setae: setae which stand at higher than a 40 degree angle from the cuticle of ant.

Flexor surfaces: the surfaces of the tibia and femur that can touch each other when the leg bends.

Frontal carinae: a pair of parallel or almost parallel ridges, medial to the antennal sockets, originating directly posterior to the clypeus on the head of an ant.

Frontal lobes: lobes formed when frontal carinae extend laterally over the antennal fossae.

Frontal triangle: a triangular area dorsal to the clypeus and between the frontal carina.

Full face view: anterior view in which the midpoints of the occipital margin, lateral margin, and clypeus are in the same focal plane.

Funiculus: the apical segments of antenna, after the first basal segment.

Gaster: terminal four or five segments of the abdomen, posterior to the petiole and/or postpetiole.

Gena: the area of the head between the compound eye and the mandible.

Head length: measured from the anterior midline of the clypeus to the posterior midline of the occipital margin; does not include the mandibles.

Infuscated: darkened, with a blackish tinge.

Inquiline: living in another ant’s nest; either commensally or parasitically.

Major: the larger castes of an ant species, excluding the queen.

Mesosomal profile: dorsal profile of the mesosoma, as seen in lateral view.

Mesosoma: the middle of the three main body parts of an ant. Includes the thorax and the propodeum.

Mesonotum: dorsal tergite of the mesothorax.

Metasternum: the posteroventral sclerite of the propodeum.

Metanotal region: the area where mesonotum and propodeum meet, representing the vestiges of a tergite called the metanotum.

Microreticulate: with a network of very fine ridges.

Minor: the smaller castes of an ant species.

Monomorphic: having one size and/or morphological caste.

Occipital margin: the posterior margin of the head.

Peduncle: an anteriorly elongated narrowing of the petiole.

Petiole: the anterior segment (and sometimes the only segment) of the ant waist, consisting of abdominal segment 2.

Polymorphic: having multiple sizes and/or morphological castes.

Postpetiole: the posterior segment (not present in all ant species) of the ant waist, consisting of abdominal segment 3.

Profemora: the femora of the anterior pair of legs.

Pronotum: the dorsal sclerite of the prothorax.

Propodeal spines: spines on the dorsum of the propodeum.

Propodeum: the first abdominal segment, fused to the thorax. Forms part of the mesosoma.

Prothorax: the first thoracic segment.

Psammophore: an array of long setae, forming a basket, on the ventral surface of the head.

Pubescence: short fine setae which are appressed along the cuticle.

Punctate: with numerous fine pits.

Rugae: wrinkle-like ridges, often in parallel.

Scape: elongate basal segment of antenna.

Sclerite: an integumental plate of the exoskeleton.

Striae: impressed lines.

Tergite: dorsal sclerite of a segment.

Truncate setae: setae that are thick and squared off at the apex.