The Ants of Africa Chapter 6 - Taxonomic Criteria & Glossary

Technical details of the Taxonomic Section

My drawings (labelled BT plus date of digitisation) were of specimens mounted on card points. I attempted to blend accuracy (of what I felt were diagnostic details) and artistic impression (to convey something of the general appearance of the specimen). They were drawn as seen under a WILD M5 stereomicroscope fitted with a camera lucida type drawing tube, and using incident illumination from a WILD low voltage source. The original drawings were made in black Indian ink on art paper. The magnification chosen for any one species was generally such that the whole ant could be seen filling a single field of vision, and an (approximate) scale is indicated on each drawing.

To further aid identification, brief descriptive notes are given, together with the following measurements (all in mm):
Total Length, TL, when outstretched from mandibular apex to gastral apex;
Head Length, HL, in a straight line from anterior clypeal margin to the mid-point of the occiptal margin;
Head Width, HW, maximum width (usually behind the eyes in full-face view);
Scape Length, SL, straight line length from base to apex, excluding any basal constriction;
and Pronotal Width, PW, maximum width in dorsal view.

In some instances calculation of comparative measurements is necessary, for example,
Scape Index, SI = (SL X 100)/HW ; Cephalic Index, CI = (HW X 100)/HL ; Ocular Index, OI = (EL X 100)/HW [EL is eye length].

My own drawings are all labelled with BT . To ensure access to older figures, I have included numeorus drawings culled from historic publications, all are clearly labelled as to source, e.g. from Wheeler (1922, labelled W'22 ) and from Bernard (1952, labelled B'52 ). I have drawn attention also to other illustrations of African ants, notably in Hölldobler & Wilson (1990), and noted where the original publication was listed by Bolton (1995) as being illustrated.

In November 2001, I made use of computer scanning to add images of specimens, for instance those sent to me by the Cameroon Wolbachia project led by Professor Doyle McKey. This gives a reasonable impression of colour and shape, but, as with photographs, structural minutiae are not clearly differentiated. The latter situation had recently changed dramatically with the adoption by several groups of the "photomontage" technique (e.g. Antweb); by multi-layering this gives near perfect photographs. It is, however, both very expensive and very time-consuming, and I have found that a simple digital camera used for taking photographs through one eyepiece of a bincoular dissecting microscope gives rapid and quite useable images. Several images, showing different aspects, details, and so-on can be combined using again simple computer imaging software. I have thus been able to add many photographs to the site.

NOTES:

Within each taxonomic level the various components are listed in alphabetical order.

Forms known or identifiable only by code letters and numbers are listed after named species.

The names of collectors who have not themselves published their findings are shown in brackets with initials.

Comments and collections from Nigeria are mine unless specifically indicated.

In the notes and elsewhere in the general text the use of the pyrethrum knockdown technique for sampling is denoted "pkd".

Click - Colours

In 2004, I have compiled a colour chart collating written descriptions and modern photographic images.

Nomenclature and glossary

The differentiation of species using dichotomous keys uses a number of body parts as the defining elements. Most of the body parts are shown in the labelled drawings, others are listed below. The glossary draws on Bolton (1973a) and Bolton & Collingwood (1975).

Also useful may be the illustrations explained on the Myrmicaria page.

Taxonomic terms
In some early description the body length is expressed in terms of "lines" - these were 1/12 of imperial inch; 1 line = 2.117 mm
The word hair is used throughout rather than the more traditional seta (plural setae).
Acidopore - a circular or subcircular orifice formed by the apex of the hypopygium (last visible gastral segment) in the subfamily Formicinae.
Antennal scrobe - a longitudinal depression in the side of the head, either above or below the eye, which can accommodate the scape or the whole of the antenna.
Carina (te) - ridge (ridged or furnished with a raised line or keel).
Clavate clubbed or enlarged at the tip.
Costulate - in narrow ridges.
Crenulate - finely notched or scalloped.
Denticulate - with minute tooth-like projections.
Emarginate - notched, with a piece of any shape cut from the margin.
Falcate - bent or curved like a sickle.
Flagellate - whip-like, often wavy.
Fovea - small depression or pit.
Gena - the cheek.
Geniculate - abruptly bent, elbowed.
Gula (r surface) - the median underpart of the head.
Lamella - leaf-like plate.
Pectinate - with branches like a comb.
Pilosity - hairiness (especially covered with soft, flexible hair).
Punctate - with fine punctures or pits.
Pygidium - the last visible gastral tergite.
Reticulate - meshed, like network.
Rugose - marked by rugae or wrinkles.
Spatulate - with broadly elongated apex.
Squamiform - having the shape of a scale.
Striate - in fine ridges or lines.
Suborbicular - hairs with rounded apices.
Trifid - split in three by deep clefts as notches.

Italian to English - Emery (1916b: 88-90) defined taxonomic terms in Italian; his images for workers are right.

French to English
In translating papers originally written in French, I have used the terms as follows:-
arêtes = ridge, edge or flange;
arqué = arcuate;
arrondi = rounded;
atténué = attenutated (less extreme);
comprimé = compressed;
dressée = raised;
effacée = faint (eroded);
épais = thick (wide);
épinotum = epinotum, modern usage = propodeum;
fossette = hair pit (or punctule);
inermes = rounded, i.e. not a distinct spine;
lisses = smooth, polished;
massue = antennal club;
rides = rugae (wrinkles), hence rideé = rugose;
sillon = post-clypeal notch;
trapue = thick-set (stocky) in build or appearance.

German to English
Soldat = soldier or major
Anatomy:- Kopf = head; Netzauge = compound eye; Schaft = scape; Fühlergrube = feeler groove = antennal scrobe; Stirnleiste = frontal carina; Giessel = whip, funiculus; Körper = body; Körperlange = body length TL; Basalfläche = dorsum of propodeum (metanotum); Höcker = hump; Knoten = knot (pedicel); Schenkel = femur (shank); Bauch = belly, abdomen, gaster; Querwulst = transverse welt, scutellum (quer = tranverse); Querlieste = transverse ridge/ledge; Dorn(en) = thorn(s); Dörnchen = spine; Zahn = tooth; Haar = hair; Punkt = puncture, point, pit; punktiert = punctuated (puncturation); Stielchenglied = petiole (and postpetiole) [pedicel] (Glied = link);
so = as; genetzt = reticulated; doppelt = double
hinter = hind; mitte = mid-; erste = first; zweiter = second; dritter = third; dreimal = three times; viertel = fourth (quarter)
längsrichtung = longitudinal; längsgestreift = longitudinally striate
kurz = short; lang = long; gross = large; breit = broad; dick = fat, thick; dicht = dense; stärk = heavily/highly; gewolbt = vaulted; niedergedrückt = depressed; stumpf = blunt; gerundet = rounded; spitzwinklig = sharp angle/point; rechtwinklig = right-angle; glänzend = shiny

Other terms used in publications on ants (taken from the glossary in Schneirla, 1971, and other sources):

Allometric growth - differential growth, usually with regular ratios of body parts in different morphs (as in Dorylus).
Claustral - colony founding by a fertilised female living in seclusion and feeding the first members of her colony.
Commensal - species which feed upon the food supplies of another species but without harming the host species.
Dichthadiigyne - a special type of female in some types of ant which are wingless, without ocelli and capable of periodic enlargement of the gaster and a high reproductive output.
Epigaeic - a species living on the surface of the earth or arboreally.
Ergatoid or Ergatogyne - a worker-like female, wingless and usually capable of laying eggs.
Hypogaeic - adapted to an underground mode of existence, with or without surface activity.
Legionary - predation combined with nomadism, found in some ponerines and dorylines.
Monogyny - having only one queen per colony.
Trophallaxis - exchange of food or other substances between members of a colony of social insects.
Trophosphere - area in which food is available to a colony.

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