SUBFAMILY MYRMICINAE - Genus Messor
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The Ants of Africa SUBFAMILY MYRMICINAE - Genus Messor |
| Contents - Myrmicinae - MYRMICINAE Introduction |
With
members previously placed in Cratomyrmex Emery.
In Tribe PHEIDOLINI.
Diagnostic Features - Granivorous ants, most strongly polymorphic. Ventral surface of head with a psammaphore (a basket-like array of long, curved hairs beneath the head, used to carry sand). Mandibles strongly curved, usually dentate in smaller workers. Propodeum armed with a pair of blunt teeth. Node of petiole emarginate above in large workers.
The original genus definition, as a subgenus of Aphaenogaster,
Forel (1890a: lxviii) - is at
.
Emery's (1892d) definition of Cratomyrmex - is at
.
Described by Bolton (1973a) as restricted to the savannah regions of
West Africa and also in the coastal plains. Their nests are built directly
into the ground with a crater-like entrance. See also Bolton (1982) but
note that he gave only HW (= head width) measurements on the grounds that
other measurements have little use in diagnosis because of the often great
polymorphism. The full text of Bolton's revision can be seen at -
.
Messor ferreri Collingwood (1993) post-dates that review. I also
have included aegyptiacus and barbarus as recorded from
Sudan, Ethiopia and Somalia but extralimital to Bolton (1982)
Jean-michel Kersaudy of Nice, France, drew my attention to my mistake in citing the dimensions (from Bolton, 1982) as TL instead of HW (July 2001 email). This I have now corrected and given the approximate TL ranges from his own observations and those of Bernard, Bolton, etc. Jean-michel also kindly sent me the photograph of Messor cephalotes taken in Kenya (by Jane BURTON near Lake Nakuru, copyright Bruce Coleman Agency).
Key to workers of species from sub-Saharan Africa (developed and expanded from Bolton, 1982)
| ¤ | Questionable occurrence as all early records and may be aegyptiacus - i.e. with propodeal teeth or spines; if true barbarus would lack a distinct psammophore | Ethiopia, Somalia & Sudan - barbarus |
| ¤ | Queen only - nomen nudum | Namibia - incisus |
| 1 | First gastral tergite without hairs or no more than a single posterior transverse row | 2 |
| -- | First gastral tergite with hairs more or less evenly distributed over whole surface | 8 |
| 2 | Dorsum of propodeum with one or more pairs of standing hairs | 3 |
| -- | Dorsum of propodeum without standing hairs | 7 |
| 3 | Propodeum without any sign of teeth (note some large specimens of galla have triangular flanges at the junction of the propodeum dorsum and declivity) | 4 |
| -- | Propodeum always with teeth | 6 |
| 4 |  Petiole
without a tooth at posteroventral corner; dorsum of head entirely smooth
other than a rugulose mid-dorsal strip; TL 4-12 mm; red-headed, alitrunk
often darker (varieties with overall darker shading) |
Sahel zone and NE Africa - galla |
| -- | Petiole with distinct tooth at posteroventral corner (may be synonymous) | 5 |
| 5 |  TL
7-9 mm; head wider than long with parallel sides; dark reddish to
blackish-brown, funiculi & tarsi light brown |
Congo - ruginodis |
| -- |  Holotype
worker TL 11.2 mm; entirely black |
Kenya - ferreri |
| -- | Propodeum always with teeth | -- |
| 6 |  Dorsum
of head with coarse dense reticulo-punctate sculpturation all over;
uniform very dark blackish-brown |
Niger, Mali - collingwoodi |
| -- |  TL
4-8 mm; generally ferruginous, gaster piceus; overall matt; probably
without hairs on the propodeum; well developed psammophore; propodeal
teeth variable but always present |
Sudan & Egypt, North Africa - aegyptiacus |
| -- | Dorsum of propodeum without standing hairs | -- |
| 7 | Head wholly covered with dense longitudinal rugulae, with reticulo-punctate ground sculpturation; TL 5-8 mm; red, posterior of gaster dark brown | Southern Africa - luebberti |
| -- |  Head
entirely smooth, sometimes with a short central rugulose area; TL 5-7 mm
(major unknown); more generally dark |
Kenya - angularis |
 |
First gastral tergite with hairs more or less evenly distributed over whole surface | -- |
| 8 | Basal third of first gastral tergite strongly and conspicuously sculptured with rugulae, costulae, coarse reticulopuncturation, or a combination | 9 |
| -- | Basal third of first gastral tergite unsculptured except for hair pits and very faint patterning | 10 |
| 9 |  In
full-face view head with lateral projecting hairs; petiole and
postpetiole coarsely rugose; TL 6-12 mm; generally dark red, head
lighter with anterior angles blackish; appendages and gaster dark
red-brown |
West Africa & Congo Basin - regalis |
| -- |  In
full-face view head without lateral projecting hairs; petiole and
postpetiole finely sculptured; TL 6.5-13 mm (largest major workers to 18
mm); red to reddish dark-borwn, often with gaster darker than head and
alitrunk |
East Africa - cephalotes |
| 10 | Posterior half of clypeus with a distinct raised central step or welt | 11 |
| -- | Posterior half of clypeus without a distinct raised central step or welt, usually flat or slightly concave | 12 |
| 11 | TL 7-11 mm; all red except gaster | Angola & Namibia - tropicorum |
| -- |  Eyes
relatively large, ca 0.25 HW, in HW range 2.50 to > 4.00; TL 5.5-11
mm; slender with relatively small head; base of scape with a small
tooth; more or less uniform dark brown or brownish-red, appendages
lighter to yellowish; pilosity reddish |
Southern Africa - denticornis |
| 12 |  In
HW range 2.80 to > 4.00 sides of head conspicuously evenly convex;
propodeal profile relatively long & low |
Southern Africa - striatifrons |
| -- | In HW range 2.80 to > 4.00 sides of head approxinmately straight; propodeal profile relatively short & high | 13 |
| 13 | Body pilosity very dark, deep red-brown to blackish | Southern Africa - piceus |
| -- | Body pilosity pale, white or silvery to yellowish | 14 |
| 14 |  Head
of major workers red, alitrunk and gaster much darker; TL 4.5-9 mm; head
of majors one-sixth wider than long |
Southeast Africa - decipiens |
| -- |  Head
of major workers brown to black, more or less concolourous with alitrunk
and gaster; TL 6-11 mm |
Southern Africa - capensis |
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MYRMICINAE Introduction | © 2007 - Brian Taylor CBiol
FIBiol FRES 11, Grazingfield, Wilford, Nottingham, NG11 7FN, U.K. |
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