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; TL 7-8 mm |
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 |  TL 7.4-7.6 mm; 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 |
| -- |  TL 5.5-5.7 mm; 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 |
| -- |  TL 4.8 mm; propodeum not marginate, dorsum rounding into
sides and declivity |
Congo Basin - alexisi |
| 5 |  TL 6.5-7.0 mm; in dorsal view sides of propodeum widening
below lateral margins; sides of face concave |
Ghana - latharis |
| -- |  TL
6.5 mm; 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 |  TL 6.1 mm; 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 |  TL 5.5-6.4 mm; promesonotal suture broad and deeply
impressed; propodeum without a median tuberculiform prominence between
the spines |
West Africa & Congo Basin - monista |
| -- |  TL 4.8-5.6 mm; 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 |
 TL 7.7-8.5 mm; 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 |  TL 5.9 mm; median clypeal margin with anterior projecting
lobe, slender |
Congo Basin - volkarti |
| -- |  TL 5.9-6.1 mm; median clypeal margin arcuate and entire,
stouter |
Congo Basin - lanuginosa |
| 14 |  TL
6.1-6.5 mm; 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 |
| -- |  TL 5.7-6.1 mm; 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 |  TL 5.7-5.9 mm; 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 |
| -- |  TL 5.2-5.6 mm; head sculptured, but without a groove or
pit, and alitrunk without sutures |
Ghana - khepra |
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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 |  TL 6.8-7.6 mm; 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 |  TL 7.2 mm; sculpturation of head between eye and frontal
carina regularly and finely striato-rugose; dorsum of mesonotum
laterally angled |
Uganda - transiens |
| -- |  TL 4.4-4.8 mm; 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 |  TL 6.2 mm; 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 |  TL 7.0-8.1 mm; gaster finely longitudinally striate |
South Africa - arnoldi |
| -- | Gaster finely reticulo-punctate | 23 |
| 23 |  TL 5.9-7.6 mm; 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 |  TL 6.1-7.0 mm; propodeum with a 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 |
| -- |  TL 6.4-7.5 mm; propodeum with a 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 | TL 7.0-8.9 mm; petiole with a single pair of
well-developed spines at dorsolateral corners and small spines between |
West Africa & Congo Basin - nigrita |
| -- |  TL 6.7-7.3 mm; petiole with two pairs of well-developed
spines, dorsal pair being longer |
South Africa - durbanensis |
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Metanotal grove distinct, broad and always impressed | . |
| 26 | Petiole with two spines | 27 |
| -- | Petiole with more than two spines | 28 |
| 27 |  TL 10.2-11.6 mm; petiolar spines subparallel and hooked
apically, clypeus carinate, pubescence golden |
. |
| . |  |
West Africa & Congo Basin - laboriosa |
| -- |  TL 8.3-8.7 mm; petiolar spines divergent, curved but not
hooked, clypeus smooth, pubescence not golden |
S Congo Basin & Angola - wellmani |
| . | Petiole with more than two spines | . |
| 28 |  TL 4.7-6.7 mm; 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 |  TL 7.4-7.8 mm; 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; entire body
finely and densely reticulate, dully shining |
Ghana - esarata |
| 32 |  TL 8.6-9.1 mm; 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 |  TL 6.8-7.6 mm; 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 |  TL < 6 mm; pronotal dorsum strongly concave
transversely, lateral margins flanged |
Congo Basin - aerope |
| -- | Pronotal dorsum no more than shallowly concave, lateral margins not flanged | 35 |
| 35 |  TL 6.7-7.1 mm; 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 |
| -- |  TL 5.0-5.4 mm; 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 erect hairs | 37A |
| -- | Antennal scapes without erect hairs | 38 |
| 37A |  TL 5.4-5.9 mm, CI 79-86, SI 128-130; antennal scapes with numerous erect hairs
projecting from the shaft; apical half of scape yellowish-brown; propodeum from above with straight sides |
. |
| . |  |
West Africa & Congo Basin - asomaningi |
| -- |  TL
5.3 mm, CI 94, SI 100; antennal scapes with few erect hairs; head with
flatter occiput in full face view, lateral angles near square;
propodeum from above with arcuate sides; median spines on petiole
apparently much broader based; only extreme tip of funiculus lighter,
rest black; head and alitrunk sculpturation much finer and more regular |
Congo - new species Congo Sud 2007 |
| 38 |  TL 4.9-5.1 mm; 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 |  TL 5.6 mm; petiole with lateral spines enormously
developed, dorsal pair reduced to spines |
Congo Basin - cornuta |
| -- | Petiole with both pairs of spines similar | 40 |
| 40 |  TL 5.5-6.2 mm; 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 |
| -- |  TL 5.2-6.3 mm; 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 |  TL 7.8-9.2 mm; propodeum not marginate. Entire body very
deeply and regularly striate |
West Africa & Congo Basin - sulcata |
| -- | Propodeum marginate | 42 |
| 42 |  TL 11.3-13.2 mm; 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 |  TL 9.4-11.2 mm; 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 |
| -- |  TL
11.2-11.4 mm; pronotum with elongate widely divergent spines; head with
fine dense spiculation; pubescence dense and very coarse on the alitrunk |
Congo Basin - new species - ayousi |
| 45 |  TL 9.3-13.7 mm; 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 |  TL 10.8-14.1 mm; 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 |
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West Africa & Congo Basin - militaris |
| -- | TL 12.6-14.4 mm; alitrunk without flanged margination and flat to weakly convex; overall sculpturation of fine superficial reticulation; eyes flat or nearly so | East Africa - medusa |
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Subfamily Formicinae |
© 2007, 2008, 2009, 2010 - Brian Taylor CBiol FSB FRES 11, Grazingfield, Wilford, Nottingham, NG11 7FN, U.K. |
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