SUBFAMILY FORMICINAE - Genus Polyrhachis subgenus Myrma
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The Ants of Africa SUBFAMILY FORMICINAE - Genus Polyrhachis subgenus Myrma |
| Contents - Formicinae - FORMICINAE Introduction |
Genus Polyrhachis F.Smith (1857a: 58)In Tribe CAMPONOTINI. Diagnostic Features - Antennae 12-segmented, with the scapes
inserted some distance behind the posterior clypeal margin. Eyes well
developed. Mandibles usually with five, rarely four teeth. Pronotum
armed with a pair of spines, teeth or tubercules; the propodeum
usually similarly armed or with a pair of ridges, rarely with only a
single transverse ridge or unarmed. Promesonotal suture usually
present, development of the metanotal groove variable. Margination of
the alitrunk variable, often present and complete but showing all
stages through to a fully emarginate condition. Petiole usually with
four but occasionally two or six spines or teeth of variable
configuration. Acidopore not borne upon a conical projection of the
hypopigium, usually concealed by the pygidium when not in use. Smith's
(1857a) genus definition is at
Fully revised by Bolton (1973b), all the species fall within the
subgenus Myrma Billberg (1820:104). This placement was
supported by Dorow (1995a: 30). Bolton's full text can be found at -
Bolton,
B. 1973. The ant genus Polyrhachis F. Smith in the
Ethiopian region (Hymenoptera: Formicidae). Bull.
Brit. Mus. (Nat. Hist.) Entomol. 28:
285-369.
View
or download
entire
file (6.8M) Billberg, G.J. 1820. Enumeratio Insectorum in Museo G. J.
Billberg. Stockhom. 138 pp - not listed in HNS Santschi's (1939c) key to Pseudocrytomyrma species, termed
by Bolton (1973b) as the revoili complex, is at
Radoskowsky (1881: 197) listed Polyrhachis setulosus F Smith from Angola, collected by Welwitsch. Bolton (1973: 352) reported neither he, nor, earlier, Wheeler (1922) could find any mention of this species in the Smith literature, let alone any description, so he regarded the name as a nomen nudum. Bolton (1973a: 352) also noted that the F Smith (1858: 73) statement of Polyrhachis consimilis being from Sierra Leone was probably an error, as the only related species are known solely from the Indo-Australian Region. |
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| ¤ |  Queen
only |
Cameroun - andrei |
| 1 | Clypeus with a shallow, rectangular lobe flanked by a pair of denticles or teeth; eyes situated well up on the head, usually not breaking the outline of the sides in full face view; alitrunk broadened and foreshortened, with a swollen appearance in dorsal view; pronotum always marginate, at least for part of its length, but either the mesonotum or propodeum or both not marginate; propodeum unarmed, the declivity extremely deep | 2 |
| -- | Clypeus either arcuate and entire or with a truncated median lobe; eyes breaking the outline of the head, except when the eyes are flat; alitrunk without a foreshortened and swollen appearance; alitrunk usually either marginate or totally without lateral margination; if partially marginate then propodeum armed | 6 |
| 2 | Petiole armed with two spines or teeth | 3 |
| -- | Petiole armed with four spines or teeth | 4 |
| 3 |  Propodeum
without a posterior transverse margination separating the dorsum from
the declivity; petiole dorsolaterally with two long spines, curved
backwards and somewhat outwards at their apices, so that the whole
petiole is lyre-shaped |
West Africa & Congo Basin - curta |
| -- |  Propodeum
with a weak posterior transverse margination separating the dorsum from
the declivity. Petiole dorsolaterally with a pair of small triangular
teeth |
Ghana - lestoni |
| 4 |  Propodeum
marginate laterally and posteriorly, separating dorsum |
5 |
| -- |  Propodeum
not marginate, dorsum rounding into sides and declivity |
Congo Basin - alexisi |
| 5 |  In
dorsal view sides of propodeum widening below lateral margins; sides of
face concave |
Ghana - latharis |
| -- |  Propodeum
not wider below lateral margins; sides of face straight |
Congo Basin - limitis |
| . | Clypeus either arcuate and entire or with a truncated median lobe; eyes breaking the outline of the head, except when the eyes are flat; alitrunk without a foreshortened and swollen appearance; alitrunk usually either marginate or totally without lateral margination; if partially marginate then propodeum armed | . |
| 6 | Pronotum not at all marginate | 7 |
| -- | Pronotum marginate at least for part of its length, present as a raised or projecting flange, a ridge or an acute angle separating the dorsum from the sides | 16 |
| 7 |  Eyes
flat and somewhat sunk into the surface of the head |
Cameroun - platyomma |
| -- |  Eyes
convex, not sunk into the surface of the head |
8 |
| 8 | Metanotal groove broad and deeply impressed; propodeum armed with a pair of long upturned spines; petiole with four long back-curved spines; dorsum of alitrunk with numerous stout, usually yellow hairs | 9 |
| -- |  Metanotal
groove weakly developed or absent. propodeum unarmed or with a pair of
tubercles, teeth or ridges which are notably smaller than those of the
pronotum; petiole with a dorsal pair of spines and a lateral pair of
teeth or shorter spines; no or only fine hairs on the alitrunk dorsum |
10 |
| 9 |  Promesonotal
suture broad and deeply impressed; propodeum without a median
tuberculiform prominence between the spines |
West Africa & Congo Basin - monista |
| -- |  Promesonotal
suture narrow, not impressed. Propodeum with a median tubercular
prominence between the spines |
West Africa & Congo Basin - spitteleri |
| 10 | Antennal scapes or alitrunk dorsum or both with erect hairs; mesoscutellum not visible on alitrunk dorsum | 11 |
 Antennal
scapes and alitrunk dorsum without erect hairs; mesoscutellum visible on
alitrunk dorsum |
South Africa - gamaii | |
| 11 | Pronotal dorsum sculptured, armed with a pair of distinct spines | 12 |
| -- | Pronotal dorsum smooth and polished, armed with a pair of small-minute teeth or tubercles | 15 |
| 12 | Propodeum armed posteriorly with a pair of transverse ridges separating the dorsum from the declivity | 13 |
| -- | Propodeum armed posteriorly with a pair of short upcurved teeth, between which the dorsum curves into the declivity | 14 |
| 13 |  Median
clypeal margin with anterior projecting lobe, slender |
Congo Basin - volkarti |
| -- |  Median
clypeal margin arcuate and entire, stouter |
Congo Basin - lanuginosa |
| 14 |  More
than 30 erect hairs on each scape; dorsum of mesonotum and propodeum
with rugose or rugo-reticulate sculpture; pubescence at least partly
masking alitrunk sculpture |
Eastern & southern Africa - revoili |
| -- |  Scape
with not more than 10 erect hairs; dorsum of mesonotum and propodeum
sharply rugose |
West Africa & Congo Basin - weissi |
| Pronotal dorsum smooth and polished, armed with a pair of small-minute teeth or tubercles | . | |
| 15 |  Head
unsculptured, with a short longitudinal groove terminating in a pit-like
depression posteriorly, close to the antennal insertion; dorsum of
alitrunk with sutures, albeit poorly developed |
Ghana - braxa |
| -- |  Head
sculptured, but without a groove or pit, and alitrunk without sutures |
Ghana - khepra |
 |
Pronotum marginate at least for part of its length, present as a raised or projecting flange, a ridge or an acute angle separating the dorsum from the sides | . |
| 16 | Metanotal groove represented only by a line or an indistinct scoring; metanotal groove never impressed, sometimes absent | 17 |
| -- | Metanotal grove distinct, broad and always impressed | 26 |
| 17 | Antennal scapes with numerous erect hairs at right angles to the shaft | 18 |
| -- | Antennal scapes without erect hairs | 20 |
| 18 |  Propodeum
with a pair of transverse ridges separating the dorsum from the
declivity, the ridges fail to meet medially and a small but distinct gap
is present |
West Africa & Congo Basin - otleti |
| -- | Propodeum with a pair of teeth or minute tubercles, between which the dorsum curves into the declivity over its entire width | 19 |
| 19 |  Sculpturation
of head between eye and frontal carina regularly and finely
striato-rugose; dorsum of mesonotum laterally angled |
Uganda - transiens |
| -- |  Sculpturation
of head between eye and frontal carina an irregular rugo-reticulum;
dorsum of mesonotum laterally rounded |
Ghana - regesa |
| . | Antennal scapes without erect hairs | . |
| 20 |  Propodeum
not marginate laterally, pronotum very weakly marginate for about half
its length. sculpturation everywhere a fine reticulation or
reticulate-puncturation |
Cameroun - aenescens |
| -- | Propodeum marginate laterally; pronotum marginate throughout its length. Sculpturation of alitrunk a fine reticulate-puncturation overlaid by longitudinal rugae or a loose rugoreticulum | 21 |
| 21 |  Propodeum
with a transverse ridge running between the spines of teeth and
separating the dorsum from the declivity; ridge with a median tooth |
22 |
| -- |  Propodeum
without such a transverse ridge and no median tooth, petiole with a
single pair of well-developed dorsolateral spines and no more than small
teeth between on dorsum |
25 |
| 22 |  Gaster
finely longitudinally striate |
South Africa - arnoldi |
| -- | Gaster finely reticulo-punctate | 23 |
| 23 |  Apex
of scape dramatically broadened, concealing first segment of funiculus;
eyes usually flat |
Sahel savannah - viscosa |
| Apex of scape not dramatically broadened, eyes convex | 24 | |
| 24 |  Propodeum
with transverse ridge between the spines and but not raised medially
into a tooth or tubercle; propodeal spines directed posterolaterally
with only slight upcurve |
Mozambique - spinicola |
| -- |  Propodeum
with transverse ridge between the spines and raised medially into a
tooth or tubercle; propodeal spines curved upwards and outwards |
Tanzania south to South Africa - cubaensis |
| . | Propodeum without a transverse ridge and no median tooth, petiole with a single pair of well-developed dorsolateral spines and no more than small teeth between on dorsum | . |
| 25 | Petiole
with a single pair of well-developed spines at dorsolateral corners and
small spines between |
West Africa & Congo Basin - nigrita |
| -- |  Petiole
with two pairs of well-developed spines, dorsal pair being longer |
South Africa - durbanensis |
|
Metanotal grove distinct, broad and always impressed | . |
| 26 | Petiole with two spines | 27 |
| -- | Petiole with more than two spines | 28 |
| 27 |  Petiolar
spines subparallel and hooked apically, clypeus carinate, pubescence
golden |
. |
| . |  |
West Africa & Congo Basin - laboriosa |
| -- |  Petiolar
spines divergent, curved but not hooked, clypeus smooth, pubescence not
golden |
S Congo Basin & Angola - wellmani |
| . | Petiole with more than two spines | . |
| 28 |  Petiole
with six spines or teeth the smallest pair situated behind the lateral
pair of spines |
. |
| . |  |
West Africa & Congo Basin (Uganda forest)- decemdentata |
| -- | Petiole with four spines or teeth | 29 |
| 29 | Pronotal dorsum without erect hairs | 30 |
| -- | Pronotal dorsum with erect hairs | 36 |
| 30 | Dorsum of head with a pair of erect hairs situated on a level with the posterior margins of the eyes, or, if lost pits, marking location | 31 |
| -- | Dorsum of head without erect hairs | 32 |
| 31 |  Anterior
clypeal margin with a small shallow impression or notch medially;
antennal scapes relatively extremely long; propodeal margins slightly
arcuate and widening to position of teeth |
Ghana - decellei |
| -- |  Anterior
clypeal margin arcuate and entire; antennal scapes relatively much
shorter; propodeal margins straight |
Ghana - esarata |
| 32 |  Covered
overall with very dense silvery pubescence; pronotum with long
downcurved spines |
East & southern Africa - schlueteri |
| -- | Pubescence usually sparse, if dense then not silvery; pronotal spines long or short but not downcurved | 33 |
| 33 |  In
posterior view the side of the head at the ventral margin of the eye
projecting below the eye and forming a shield or blinker; in side view
the ventral margin appearing concave, so that the eye is kidney-shaped;
in full-face view the sides of the head in front of eyes noticeably
concave |
. |
| . |  |
West Africa & Congo Basin - concava |
| -- | The side of the head not projecting; sides of head not noticeably concave in full-face view | 34 |
| 34 |  Pronotal
dorsum strongly concave transversely, lateral margins flanged |
Congo Basin - aerope |
| -- | Pronotal dorsum no more than shallowly concave, lateral margins not flanged | 35 |
| 35 |  Sculpturation
of head a fine dense reticulate-puncturation; on sides of head below and
in front of the eye, and on the genae numerous distinct pits usually in
groups of 3-4 |
West Africa & Congo Basin - alluaudi |
| -- |  Sculpturation
of head a fine, dense reticulation; same sculpturation all over head |
West Africa & Congo Basin - rufipalpis |
| . |
Pronotal dorsum with erect hairs | . |
| 36 | Lateral pair of petiole spines as long as, or longer than, the dorsal spines | 37 |
| -- |  Lateral
pair of petiole spines short, always shorter than the dorsal spines and may be
reduced to a pair of short teeth |
41 |
| 37 |  Antennal
scapes with numerous erect hairs projecting from the shaft |
West Africa & Congo Basin - asomaningi |
| -- | Antennal scapes without erect hairs | 38 |
| 38 |  First
gastral tergite finely longitudinally striate-rugose, with numerous
small punctures between the rugae |
West Africa & Congo Basin - phidias |
| -- | First gastral tergite finely superficially reticulate or reticulate-punctate | 39 |
| 39 |  Petiole
with lateral spines enormously developed, dorsal pair reduced to spines
|
Congo Basin - cornuta |
| -- | Petiole with both pairs of spines similar | 40 |
| 40 |  Face
with a short, longitudinal shallow groove terminating in a depression
posteriorly, situated close to the outer margin of the antennal socket;
dorsum of propodeum extremely finely and longitudinally striate |
West Africa & Congo Basin - lauta |
| -- |  Face
without such a groove; dorsum of propodeum coarsely and distinctly
transversely striate |
West Africa & Congo Basin (Uganda forest) - fissa |
| . |
Lateral pair of petiole spines short, always shorter than the dorsal spines and may be reduced to a pair of short teeth | . |
| 41 |  Propodeum
not marginate. Entire body very deeply and regularly striate |
West Africa & Congo Basin - sulcata |
| -- | Propodeum marginate | 42 |
| 42 |  Dorsum
of alitrunk with no erect hairs except on pronotum; side of head without
erect hairs; gaster highly polished |
savannha areas of south Congo Basin & southern Africa - gagates |
| -- | Dorsum of alitrunk with numerous erect hairs | 43 |
| 43 | Propodeal dorsum separated from declivity by an arched transverse ridge | 44 |
| -- | Propodeal dorsum running smoothly into declivity | 45 |
| 44 | 
Pronotal spines no more than flattened triangular teeth; head with fine
dense longitudinal rugosity; pubescence sparse; numerous erect fine,
whitish, hairs all over |
Congo Basin - latispina |
| -- |  Pronotum
with elongate widely divergent spines; head with fine dense spiculation;
pubescence dense and very coarse on the alitrunk |
Congo Basin - Polyrhachis new species CAR |
| 45 |  Pubescence
sparse, not hiding the sculpturation of the alitrunk or gaster, usually
greyish in colour; narrow slender species |
. |
| . |  |
Pan-African savannah - schistacea |
| -- | Pubescence abundant everywhere, hiding the sculpturation and usually with a golden brassy or bronze tinge. | 46 |
| 46 |  Alitrunk
with marked lateral margination, especially the pronotum which usually
is extended as a raised flange; the dorsal alitrunk somewhat concave
between the margination; head with longitudinal striate-rugulation; eyes
convex |
West Africa & Congo Basin - militaris |
| . |  |
|
| -- | Alitrunk without flanged margination and flat to weakly convex; overall sculpturation of fine superficial reticulation; eyes flat or nearly so | Tanzania - medusa |
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Subfamily Formicinae | © 2007, 2008 - Brian Taylor CBiol
FIBiol FRES 11, Grazingfield, Wilford, Nottingham, NG11 7FN, U.K. |
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