ISSN 1911-2173


Ants (Hymenoptera: Formicidae) of Alberta: A key to species

based primarily on the worker caste

CJAI 22 July 4, 2013


James R.N. Glasier1, John H. Acorn2, Scott E. Nielsen2, and Heather Proctor3

1 Corresponding author: Department of Renewable Resources, University of Alberta, Edmonton, AB, T6G

2 Department of Renewable Resources, University of Alberta, Edmonton, AB, T6G 2H1,

3 Department of Biological Sciences, University of Alberta, Edmonton, AB, T6G 2E9

| Abstract | Introduction | Materials | Discussion | Checklist | Glossary | Species Key | Acknowledgments | References | PDF (11MB) | Cite this Article |

Lateral Morphology of Myrmicinae | Lateral Morphology of Formicinae | Head Morphology


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.