The Ants of Africa
SUBFAMILY MYRMICINAE - Genus Messor
Contents - Myrmicinae - MYRMICINAE Introduction

Genus Messor (Forel, 1890a)

{Messor cephalotes}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 {original description}. Emery's (1892d) definition of Cratomyrmex - is at {original description}.

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 - {original description}.
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).


Species from Egypt, Israel, Turkey, Italy and Iran can be seen on Messor concolor, Messor ebeninus, Messor foreli, Messor meridionalis, Messor nahali, Messor niloticus, Messor rugosus, Messor structor and Messor wasmanni


Key to workers of species from sub-Saharan Africa (developed and expanded from Bolton, 1982)

Messor barbarusQuestionable occurrence in sub-Saharan Africa 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 (M. ferreri seems inconsistent)
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 {Messor galla major}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; scapes of major reaching to slightly exceeding occipital margin
5
5 {short description of image}TL 7-9 mm; head wider than long with parallel sides; petiole with distinct rugose sculpturation; dark reddish to blackish-brown, funiculi & tarsi light brown.
Stitz drawing is a media worker.
.
. {short description of image}Major not reported before TL ca 13 mm Congo & Sudan - ruginodis
-- {short description of image}Holotype worker TL 11.2 mm; major entirely black, media (?) with reddish-head; petiole weakly sculptured, with a narrow node profile; propodeum obtusely angled
.
.
Messor ferreri mediaMedia (?)
Kenya & Ethiopia - ferreri
-- Propodeum always with teeth --
6 {Messor collingwoodi}Dorsum of head with coarse dense reticulo-punctate sculpturation all over; uniform very dark blackish-brown .
. {Messor collingwoodi} Niger, Mali - collingwoodi
-- {Messor aegyptiacus}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 Messor luebbertiHead wholly covered with dense longitudinal rugulae, with reticulo-punctate ground sculpturation; TL 5-8 mm; red, posterior of gaster dark brown Southern Africa - luebberti
-- {Messor angularis}Head entirely smooth, sometimes with a short central rugulose area; TL 5-7 mm (major unknown); more generally dark .
. {Messor angularis} Kenya & Sudan - angularis
return to key 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 {Messor regalis}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 .
. {Messor regalis} West Africa & Congo Basin - regalis
-- {Messor cephalotes}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-brown, 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 Messor tropicorumTL 7-11 mm; all red except gaster Angola & Namibia - tropicorum
-- {Messor denticornis}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 .
. {Messor denticornis}. Southern Africa - denticornis
12 {Messor striatifrons}In HW range 2.80 to > 4.00 sides of head conspicuously evenly convex; propodeal profile relatively long & low .
. Thumbnail may be a media worker
{Messor striatifrons}
Southern Africa - striatifrons
-- In HW range 2.80 to > 4.00 sides of head approxinmately straight; propodeal profile relatively short & high 13
13 Messor piceusBody pilosity very dark, deep red-brown to blackish
thumbnail of probable media worker
Southern Africa - piceus
-- Body pilosity pale, white or silvery to yellowish 14
14 {Messor decipiens}Head of major workers red, alitrunk and gaster much darker; TL 4.5-9 mm; head of majors one-sixth wider than long .
. {Messor decipiens} Southeast Africa - decipiens
-- {Messor capensis}Head of major workers brown to black, more or less concolourous with alitrunk and gaster; TL 6-11 mm .
. {Messor capensis} Southern Africa - capensis
Contents MYRMICINAE Introduction
2007, 2010, 2013, 2015 - Brian Taylor CBiol FSB FRES
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