SUBFAMILY MYRMICINAE - Genus Strumigenys
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The Ants of Africa SUBFAMILY MYRMICINAE - Genus Strumigenys |
| Contents - Myrmicinae - MYRMICINAE Introduction |
Revised by Brown (1954) and Bolton (1983).
Diagnostic Features - Antennae 6-segmented, with the second and third funicular segments reduced. Antennal scrobes present. Often the ventrolateral margin of the head is excised in front of the eye to form a preocular notch. Mandibles elongate, linear, with the preapical armament usually of two teeth on the distal portion of the blade, occasionally one of these teeth is missing. Apical armament of the mandible is a fork of two spiniform teeth, with or without intercalary denticles. All orange-brown, some darker.
F Smith's (1860c) genus definition is at
.
An early key to African and Madagascar dacetines is that of Santschi
(1913b); that, with modern annotation, is
.
Key to workers of African species (adapted and updated
from Bolton, 1983): in addition to the usual measurements, Bolton used
ML = straight line length of mandible from anterior clypeal margin
to the apex of the mandible, from which he used MI = ML/HL X 100
| 1 | Preocular notch present; ventrolateral margin of head impressed, notched or indented immediately forward of the eye (may be reduced in adrasora and rukha) | 2 |
| -- | Preocular notch absent; no impression of ventrolateral margin of head forward of the eye | 23 |
| - | Preocular notch present | - |
| 2 | Blade of left mandible with 1 preapical tooth (occasionally with a very small vestige of a second tooth); reticulate-punctate propodeal dorsum | 3 |
| -- | Blade of left mandible with 2 preapical teeth | 7 |
| - | Blade of left mandible with 1 preapical tooth (occasionally with a very small vestige of a second tooth); reticulate-punctate propodeal dorsum | - |
| 3 | Small TL no more than 2.5 mm | 4 |
| -- | TL at least 2.9 mm | 5 |
| 4 | 
Head with a very narrow profile; apical fork of left mandible without a
small tooth between the spiniform fork; TL 1.7-2.1 mm, HL 0.52-0.58, HW
0.36-0.41, CI 67-72, MI 55-65, SL 0.30-0.36, SI 82-92; variable brown |
Cameroun south to Angola - bernardi (part) |
| -- |  Preocular
notch deep but narrow and not continued across ventral surface of head;
TL 2.3 mm, HL 0.50, HW 0.38, CI 76, MI 54, SL 0.38, SI 98; scapes with a
rearward directed fringe of relatively long narrow hairs; mandibles
relatively short, without hairs on inner margins; pronotum with long
straight hair directed laterally; propodeum with sharp teeth;
postpetiole wuth a small ventral spongiform lobe; dark brown |
Tanzania - new species - ulugurensis |
| 5 |  Pronotal
humeri with stout feebly clavate straight hairs; scapes with only a few
and variably directed weakly spatulate hairs; propodeum without sharp
teeth; TL ca 3.0 mm (Bolton has 3.5-4.2 mm) HL 0.84-0.92, HW 0.62-0.70,
CI 74-77, MI 51-52, SL 0.52-0.58, SI 82-87; Patrizi had the colour as
testaceous (Bolton gave it as light brown, gaster darker) |
. |
| . |  Tanzania
specimens |
Kenya & Tanzania - londianensis |
| -- | 
Pronotal humeri with fine flagellate hairs; mandibles with hairs on
inner margins; scapes with rearward directed but relatively short
spatulate hairs; propodeum with sharp teeth; TL 2.9, HL 0.72, HW 0.52,
CI 72, MI 53, SL 0.46, SI 88; light brown |
. |
| . |  |
Eastern Congo basin - sarissa |
| Blade of left mandible with 2 preapical teeth | - | |
| 7 | Mandibles straight | 8 |
| -- | Mandibles distinctly bowed | 9 |
| 8 |  In
full-face view head with a distinct notch in the upper scrobe margin
above the eye; whole of alitrunk and pedicel segments densely spiculate;
spongiform appendages on pedicel nodes almost absent; apical fork of
left mandible with a strong intercalary tooth and a denticle between the
spiniform fork teeth; TL 2.7-3.3 mm, HL 0.83-0.92, HW 0.72-0.80, CI
86-91, MI 44-50, SL 0.48-0.50, SI 62-67; dull yellow to yellowish-brown |
West Africa - cacaoensis |
| -- |  Pedicel
nodes shiny, rest of head and alitrunk sculpture; ventral spongiform
appendages on pedicel nodes well developed; TL 2.2-2.8 mm, HL 0.58-0.74,
HW 0.42-0.52, CI 69-75, MI 51-58, SL 0.36-0.46, SI 82-89; dull yellow to
light medium brown or darker |
. |
| . |  |
Pan-African tropics & tramp - rogeri |
| 9 |  Preocular
notch continued on to the ventral surface of the head as a transverse
impression or groove |
10 |
| -- |  Preocular
notch not continued on to the ventral surface of the head; ventral
surface convex and without impressions behind the post-buccal groove or
impression |
17 |
| 10 | Antennal scapes relatively long (SI 79-92) | 11 |
| -- | Antennal scapes relatively short (SI 64-74) | 12 |
| 11 |  Propodeum
dorsum smooth and shining; TL 1.9-2.2 mm, HL 0.52-0.60, HW 0.36-0.40, CI
65-70, MI 50-59, SL 0.29-0.34, SI 79-86; dull yellowish-brown |
. |
| . |  |
West Africa - vazerka |
| -- | Propodeum
dorsum finely reticulate-punctate; TL 1.7-2.1 mm, HL 0.52-0.58, HW
0.36-0.41, CI 67-72, MI 55-65, SL 0.30-0.36, SI 82-92; variable brown
|
Cameroun south to Angola - bernardi (part) |
| Antennal scapes relatively short (SI 64-74) | - | |
| 12 |  Eyes
very large, maximum diameter 0.23-0.24 X HW; TL 2.3-3.0 mm, HL
0.59-0.70, HW 0.43-0.54, CI 71-77, MI 40-44, SL 0.33-0.40, SI 69-77;
dull yellow to light yellowish-brown |
Southern Africa - pretoriae |
| -- | Eyes smaller no more than 0.20 X HW | 13 |
| 13 |  Pronotal
humeri without flagellate hairs; TL 2.0-2.5 mm, HL 0.54-0.68, HW
0.40-0.53, CI 75-83, MI 44-50, SL 0.28-0.36, SI 64-72; variable yellow
to very dark brown, often gaster darker |
. |
| . |  |
West Africa & Congo Basin into S Sudan - petiolata |
| -- | Pronotal humeri with flagellate hairs | 14 |
| 14 |  Postpetiole
dorsum very finely and densely sculptured; TL 2.2-2.3 mm, HL 0.55-0.56,
HW 0.43-0.44, CI 77-79, MI 46-47, SL 0.30-0.32, SI 70-72; dull yellow |
. |
| . |  |
South Africa - faurei |
| -- | Postpetiole dorsum no more than weakly sculptured (may be concealed by a waxy bloom) | 15 |
| 15 | 
Distal preapical tooth of left mandible short and separated from the
proximal tooth by at least the length of the distal tooth; TL 1.8-2.0
mm, HL 0.48-53, HW 0.36-0.40, CI 73-76, MI 45-48, SL 0.25-0.29, SI
69-74; medium brown, gaster darker (may be wholly dark) |
. |
| . |  |
West Africa - rufobrunea |
| -- | Distal preapical tooth of left mandible short and separated from the proximal tooth by a distance much less than the length of the distal tooth | 16 |
| 16 | Extension of preocular notch on underside of head forming a sharply defined and parallel-sided groove which is narrower than the width of the eye; TL 2.1-2.3 mm, HL 0.54-58, HW 0.42-0.47, CI 75-81, MI 44-47, SL 0.27-0.31, SI 64-69; yellowish-brown to light brown | Zimbabwe - shaula |
| -- | Extension of preocular notch on underside of head forming a broad dish-like impression as broad as if not broader than the eye; with rounded edges; TL 2.1 mm, HL 0.54-55, HW 0.40-0.41, CI 74-75, MI 48-49, SL 0.28-0.29, SI 68-73; brownish-yellow, gaster dark brown | Burundi - dromoshaula |
 |
Preocular notch not continued on to the ventral surface of the head; ventral surface convex and without impressions behind the post-buccal groove or impression | - |
| 17 | Eyes small with only 8 ommatidia; mandibles with outer edge straight; TL 2.2 mm, HL 0.59, HW 0.43, CI 73, MI 49, SL 0.34, SI 79; dull brownish yellow | Angola - helytruga |
| -- | Eyes with more than 8 ommatidia; mandibles with outer edge convex; SI 65-77 | 18 |
| 18 |  Pronotal
humeri without flagellate hairs; TL 2.3 mm, HL 0.64, HW 0.45, CI 70, MI
44, SL 0.34, SI 76; yellow |
Cameroun - totyla |
| -- | Pronotal humeri with flagellate hairs | 19 |
| 19 |  In
full-face view the projecting hairs on the leading edges of the scapes
large and broadly spoon-shaped; upper scrobe margins with a broad
lamellate rim or flange; TL 2.3 mm, HL 0.61-0.67, HW 0.48-0.53, CI
79-83, MI 48-51, SL 0.34-0.36, SI 68-71; dull yellow |
Congo Basin - xenohyla |
| -- |  In
full-face view the projecting hairs on the leading edges of the scapes
slender and narrower than those on the upper scrobe margins, or slender
in both places; scrobe margins with a narrow rim or flange |
19 |
| 20 |  In
profile ventral spongiform lobe on postpetiole much smaller than visible
area of postpetiole dorsum; lamella on propodeal declivity much reduced;
TL 2.3-2.4 mm, HL 0.59-0.62, HW 0.44-0.47, CI 73-78, MI 50-54, SL
0.33-36, SI 72-77; blackish-brown to black |
. |
| . |  |
Rwanda & Burundi - adrasora (part) |
| -- | In profile ventral spongiform lobe on postpetiole at least equalling the visible area of postpetiole dorsum; lamella on propodeal declivity broad and involving the teeth | 21 |
| 21 |  In
dorsal view postpetiole with spongiform material projecting laterally at
and in front of the dorsum; TL 2.3-2.4 mm, HL 0.57-0.60, HW 0.44-0.46,
CI 75-79, MI 47-49, SL 0.30-33, SI 67-73; yellow |
East Africa - rukha (part) |
| -- | In dorsal view postpetiole with spongiform material restricted to apices of posterior transverse strip and not projecting in front of the dorsum | 22 |
| 22 |  Basigastral
costulae sparse and forming a continuous row across the tergite, without
a broad clear area medially; occiput broadly and shallowly impressed; TL
1.9-2.0 mm, HL 0.54-0.56, HW 0.40-0.41, CI 73-76, MI 43-44, SL
0.26-0.28, SI 65-68; yellowish-brown gaster darker |
Congo Basin - relahyla |
| -- |  Basigastral
costulae dense and radiating from broad medial clear area; occiput
narrowly and deeply impressed; TL 2.0-2.1 mm, HL 0.54-0.56, HW
0.40-0.43, CI 74-786, MI 46-48, SL 0.28-0.31, SI 70-74; dull yellow |
. |
| . |  |
Zimbabwe - dyshaula |
|
Preocular notch absent | - |
| 23 | Blade of left mandible with 1 preapical tooth | 24 |
| -- | Blade of left mandible with 2 preapical teeth | 27 |
| 24 |  Medium
to dark brown; TL 1.9-2.1 mm, HL 0.47-0.54, HW 0.38-0.43, CI 76-83, MI
40-43, SL 0.24-0.28, SI 62-70; |
Southern Africa - irrorata |
| -- | Brownish-yellow or yellow | 25 |
| 25 |  TL
at least 2.0 mm; apical fork of left mandible with an intercalary
denticle between the spiniform teeth; dorsum of head without a row of 4
erect hairs; head broad; TL 2.0-2.2 mm, HL 0.50-0.53, HW 0.44-0.46, CI
88-90, MI 38-40, SL 0.26-0.27, SI 57-60; brownish-yellow |
East Africa - katapelta |
| -- | TL no more than 1.8 mm; apical fork of left mandible without an intercalary denticle between the spiniform teeth; dorsum of head with a row of 4 erect hairs close to the occiput and an anterior pair; head narrower CI < 80 | 26 |
| 26 | Pronotal humeri each with a straight stout thickly clavate projecting hair; TL 1.7-1.8 mm, HL 0.45-0.46, HW 0.32-0.34, CI 70-74, MI 37-41, SL 0.24-0.25, SI 73-75; brownish-yellow | Cameroun & Gabon - paranax |
| -- | Pronotal humeri each with a long fine flagellate projecting hair; TL 1.6-1.8 mm, HL 0.41-0.47, HW 0.31-0.34, CI 71-77, MI 38-42, SL 0.22-0.25, SI 68-75; dull yellow | Congo Basin into Uganda - dextra |
|
Blade of left mandible with 2 preapical teeth | - |
| 27 | Species with short compact mandibles and short variously broadened scapes | 28 |
| -- | Species with long mandibles and slender scapes | 32 |
| 28 | Head in full face view with post-ocular area essentially heart-shaped; arboreal | 29 |
| -- | Head in full-face view with post-ocular area with straight or near straight sides | 30 |
| 29 |  Pronotal
humeri each with a stout straight laterally directed hair, with clavate
apex; petiole dorsum weakly transversely striate; TL 2.0-2.1 mm, HL
0.52-0.58, HW 0.38-0.44, CI 70-77, MI 32-36, SL 0.24-0.26, SI 57-62;
dull yellow to bronish-yellow |
West Africa - pallestes |
| -- | Pronotal humeri with projecting hairs; petiole dorsum punctate; TL 2.4-2.5 mm, HL 0.62-0.66, HW 0.48-0.50, CI 75-77, MI 35-37, SL 0.30-0.32, SI 60-63; yellowish brown | South Africa - marleyi |
| 30 |  Leading
edge of antennal scape grossly expanded into an enormous anteriorly
projecting lobe; TL 2.0-2.2 mm, HL 0.54-0.60, HW 0.51-0.57, CI 91-97, MI
34-37, SL 0.28-0.30, SI 52-55; brown |
. |
| . |  |
Congo Basin into Uganda - tetraphanes |
| -- | Leading edge of antennal scape expanded but less dramatically | 31 |
| 31 |  Mandibles
& scapes very short; TL 2.0-2.1 mm, HL 0.53-0.55, HW 0.41-0.44, CI
77-81, MI 26-30, SL 0.24-0.26, SI 55-61; medium brown |
. |
| . |  |
West Africa - spathoda |
| -- |  Ground
pilosity on head, upper scrobe margins and leading edges of scapes is of
very broad hairs; scapes flattened with leading edges expanded
cf tetraphanes; TL 1.9-2.1 mm, HL 0.50-0.53, HW 0.40-0.43, CI
80-84, MI 36-40, SL 0.26-0.28, SI 63-68; light to medium brown |
Cameroun, Angola and east into Kenya & Zimbabwe - stygia |
|
Species with long mandibles and slender scapes | - |
| 32 | Pronotal humeri without flagellate hairs | 33 |
| -- |  Pronotal
humeri with flagellate hairs |
36 |
| 33 |  Antennal
scape sharply expanded at the base then evenly tapering to the apex;
mandibles and scapes longer, head narrower; TL 2.2-2.3 mm, HL 0.61-0.64,
HW 0.41-0.43, CI 67, MI 49-50, SL 0.35-0.36, SI 84-85; brownish-yellow |
. |
| . |  |
Cameroun, Ghana & Gabon - korahyla |
| -- | Antennal scape broadest about the midlength and narrowing both ways; mandibles and scapes shorter, head broader, MI 35-41, SI 65-75, CI 74-84 | 34 |
| 34 |  Postpetiole
with smooth and shiny dorsum; TL 2.0-2.1 mm, HL 0.54-0.60, HW 0.39-0.46,
CI 74-78, MI 38-41, SL 0.30-0.32, SI 68-75; dull yellow |
eastern Africa - arnoldi |
| -- | Postpetiole weakly sculptured and dull | 35 |
| 35 |  With
quite sparse spatulate hairs; TL 2.0-2.4 mm, HL 0.49-0.60, HW 0.41-0.46,
CI 75-80, MI 35-40, SL 0.26-0.32, SI 65-71; light brown |
. |
| . |  |
Kenya - omalyx |
| -- |  Description
unavailable in HNS -all rect hairs essentially slender; scape slender
for whole length; measurements from Antweb images: TL ca 2.4 mm, HL
0.62, HW 0.48, CI 78, ML 32, MI 52, SL 0.41, SI 86; light brown |
Sao Thomé - sibyna |
|
Pronotal humeri with flagellate hairs | - |
| 36 |  Funicular
segments 2 and 3 very small so that funiculus appears to have only 3
segments |
37 |
| -- |  Funicular
segments 2 and 3 small but clearly visible |
38 |
| 37 | Lamellate flange bordering upper scrobe margins distinctly wider than the diameter of the eye, close to width of scape; petiole node in dorsal view as broad as long; TL 1.9 mm, HL 0.47, HW 0.37, CI 79, MI 43, SL 0.28, SI 76; light brown | Cameroun - bitheria |
| -- |  Lamellate
flange bordering upper scrobe margins distinctly narrower than the
diameter of the eye, much less than width of scape; petiole node in
dorsal view much broader than long; TL 1.5-1.8 mm, HL 0.42-0.46, HW
0.31-0.35, CI 72-77, MI 40-45, SL 0.22-0.24, SI 68-73; dull yellow to
brownish yellow |
Ivory Coast & Ghana - nimbrata |
| Funicular segments 2 and 3 small but clearly visible | - | |
| 38 |  Postpetiole
node sculptured; ground pilosity on head, upper scrobe margins and
leading edges of scapes is of narrow spatulate hairs; scapes slender &
cylindrical; gaster broader than head; TL 2.3 mm, HL 0.58, HW 0.44, CI
76, MI 43, SL 0.34, SI 77; brownish-yellow |
. |
| . |  |
Rwanda - murshila |
| -- |  Postpetiole
node smooth and shining |
39 |
| Postpetiole node smooth and shining | - | |
| 39 |  Maximum
diameter of eye much less than width of scape |
40 |
| -- |  Maximum
diameter of eye equal to or greater than width of scape |
43 |
| 40 |  Description
unavailable on HNS - scape short and broadened but not greatly so
relative to base and apex; measurements from Antweb images: TL ca 2.4
mm, HL 0.65, HW 0.61, CI 94, ML 30, MI 46, SL 0.36, SI 60 |
Gabon - ultromalyx |
| -- | Mandibles and scapes longer, MI 42-50 SI 70-90 | 41 |
| 41 |  Scapes
long SI 80-90; proximal preapical tooth of left mandible set behind the
mid-length of blade so that the distance to the clypeal margin is more
than twice the distance to the base of the dorsal fork; TL 2.5-2.6 mm,
HL 0.62-0.68, HW 0.44-0.50, CI 69-74, MI 45-50, SL 0.36-0.40, SI 80-90;
yellow |
South Africa - havilandi |
| -- | Scapes shorter SI 70-75; proximal preapical tooth of left mandible set close to mid-length of blade so that the distance to the clypeal margin it is less than twice the distance to the base of the dorsal fork | 42 |
| 42 |  Dorsum
of head with 6 erect hairs; ground pilosity on posterior half of head
narrowly spatulate and much narrower than on anterior half; in profile
postpetiole with ventral spongiform lobe no more than equal to the
exposed area; TL 2.0-2.1 mm, HL 0.54-0.55, HW 0.43, CI 78-80, MI 44, SL
0.30, SI 70; brown (note the Santschi drawing seems at odds with the
Bolton description) |
South Africa - traegaordhi |
| -- |  Dorsum
of head with 4 erect hairs; ground pilosity broadly spatulate
everywhere; in profile postpetiole with ventral spongiform lobe much
larger than equal to the exposed area; L 2.0-2.1 mm, HL 0.52, HW 0.41,
CI 75-79, MI 42-43, SL 0.30-0.32, SI 73-75; yellow |
Zimbabwe - mesahyla |
| Maximum diameter of eye equal to or greater than width of scape | - | |
| 43 | Blackish or blackish-brown | 44 |
| -- | No darker than brown | 45 |
| 44 | In
profile ventral spongiform lobe on postpetiole much smaller than visible
area of postpetiole dorsum; lamella on propodeal declivity much reduced;
TL 2.3-2.4 mm, HL 0.59-0.62 HW 0.44-0.47 CI 73-78 MI 50-54 SL 0.33-36 SI
72-77; mm; blackish-brown to black |
. |
| . | |
Rwanda & Burundi - adrasora (part) |
| -- | Shorter mandibles and scapes, TL 2.0 mm, HL 0.53-0.57, HW 0.43-0.46, CI 81, MI 40-43, SL 0.26-27, SI 59-60 | Cameroun - ettillax |
| 45 | Upper
scrobe margins fringed by a few conspicuous broadly spatulate to
spoon-shaped large hairs, distinctly large than ground-pilosity of the
head; TL 2.3-2.4 mm, HL 0.57-0.60, HW 0.44-0.46, CI 75-79, MI 47-49, SL
0.30-33, SI 67-73; yellow |
East Africa - rukha (part) |
| -- | 
Upper scrobe margins fringed by many inconspicuous narrowly spatulate to
slender spoon-shaped hairs, similar in size to ground-pilosity of head |
46 |
| Upper scrobe margins fringed by many inconspicuous narrowly spatulate to slender spoon-shaped hairs, similar in size to ground-pilosity of head | - | |
| 46 | Mandibles
& scapes long, MI 46-50 SI 88-85; petiole node in dorsal view at
least as long as broad; TL 2.4-2.6 mm, HL 0.62-0.70, HW 0.42-0.46, CI
64-70, MI 46-50, SL 0.39-42, SI 88-95; yellowish brown to medium brown |
. |
| . |  |
Sao Tome I., Seychelles - scotti |
| -- | Mandibles & scapes shorter, MI 42-46 SI 73-82; petiole node in dorsal view broader than long | 47 |
| 47 |  In
dorsal view all hairs on petiole, postpetiole and base of first gastral
tergite thickened or clavate; smaller, TL 1.8-2.0 mm, HL 0.49-0.52, HW
0.36-0.38, CI 73-75, MI 43-45, SL 0.28-29, SI 76-78; brownish-yellow |
West Africa and Congo basin into Burundi - hastyla |
| -- |  In
dorsal view all hairs on petiole, postpetiole and base of first gastral
tergite simple not thickened; larger, TL 2.2-2.3 mm, HL 0.59-0.61, HW
0.42-0.44, CI 70-73, MI 43-45, SL 0.33-35, SI 75-81; light brownish
yellow |
. |
| . |  |
Annobon I & Cameroun - zandala |
 |
MYRMICINAE Introduction | © 2007, 2008 - Brian Taylor CBiol
FIBiol FRES 11, Grazingfield, Wilford, Nottingham, NG11 7FN, U.K. |
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