SUBFAMILY MYRMICINAE - Genus Pyramica - subgenus Smithistruma
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The Ants of Africa SUBFAMILY MYRMICINAE - Genus Pyramica - subgenus Smithistruma |
| Genus Pyramica |
In Tribe DACETINI.
Bolton (1999) has made a radical revision and now has Smithistruma as a junior synonym of Pyramica Roger. However, for convenience, I have retained Smithistruma as a subgenus of Pyramica and so have kept the key.
Diagnostic Features - Antennae 4-segmented (former Miccostruma) or 6-segmented, antennal scrobes present. Mandibles relatively short, subtriangular, serially dentate, and concealed for most of their length by the very well developed, anteriorly projecting clypeus, which is fringed anteriorly and laterally by flattened hairs. Dorsum of head with fine scattered punctures, hairs absent except on clypeus. Dorsum of alitrunk, pedicel and gaster mostly shiny, with small, widely spaced punctures. Base of first gastric tergite with longitudinal striae. Sutures absent from dorsal alitrunk. Propodeum bidentate. Spongiform appendages of pedicel well developed.
Brown (1953g) reviewed the then known African species, his key and
descriptions are at 
.
Bolton (1983) described how all known Afrotropical species inhabit the leaf litter and topsoil layers, usually nesting directly into the ground or in rotten wood. The feeding habits of genus members were described by Déjean (1985), including Smithistruma truncatidens feeding on entomobryomorph collembolans. No species was regarded as common (Bolton, 1983) and most were represented by only a few collections and those were of few individual workers. Collecting efforts using Berlese and similar funnel extraction techniques had greatly increased the number of known species; for instance prior to Bolton's revisionary work only eight African species had been described, afterwards there were 35 separable species.
Smithistruma species C and Smithistruma species F, listed from cocoa leaf litter, and Smithistruma species E, listed from soil under Euphorbia, at the Mampong Cemetery farm in Ghana (Room, 1971), are clearly the three species emarginata, hensekta and sharra (see below) but they are not separable from the information given by Bolton (1983). A further, presently unnamed, species was found by Belshaw & Bolton (1994b), in Ghana, four workers collected from leaf litter, under cocoa at Effiduase and Bunso.
Key to subgenus Smithistruma workers from Africa (adapted from Bolton, 1983):
| 1 | Antennae with 4 segments | 2 |
| -- | Antennae with 6 segments | 8 |
| 2 | In full-face view, clypeus with a convex margin; pronotum with a median longitudinal carina and pronotal humeri each with a single flagellate hair | 3 |
| -- | In full-face view, clypeus with a concave margin; pronotum without a median longitudinal carina and pronotal humeri without flagellate hairs | 5 |
| 3 |  Clypeus
broad, seen in full-face view expanded laterally far beyond the line of
the outer margins of the closed mandibles; clypeus without hairs; TL
1.2-1.3 mm; uniform dull yellow to yellowish-brown |
Kenya, Zimbabwe & Ivory Coast - marginata |
| -- | Clypeus narrow; edges more or less parallel with outer border of closed mandibles; dorsum of clypeus with abundant short curved hairs | 4 |
| 4 |  Pronotum
sharply marginate laterally, dorsum unsculptured; head relatively broad
and scapes short; TL 1.7-1.8 mm; yellow to yellowish-brown |
West Africa & Congo Basin - tacta |
| -- |  Pronotum
not marginate, dorsum weakly sculptured; head relatively narrow and
scapes long; TL 3.0 mm; colour medium-brown |
Cameroun - vodensa |
| 5 |  Entire
body with yellow and black tiger stripes; TL 2.0-2.2 mm |
West Africa - tigrilla |
| -- | Body uniformly coloured | 6 |
| 6 |  In
profile dorsum of head with a pair of short erect hairs; 4-segmented
antennae; TL 1.7-1.8 mm; yellow to light brownish-yellow |
Kenya, Tanzania & Angola - mandibularis |
| -- | In profile dorsum of head without erect hairs | 7 |
| 7 |  Anterior
half of clypeus with a broad longitudinal depression filled with short
scale-like hairs; subbasal elbows of scapes extensively developed and
angular; pronotal dorsum with dense fine longitudinal rugulae or
costulae; TL 2.0 mm; dark brown |
Ivory Coast & Ghana - fulda |
| -- |  Anterior
half of clypeus without an impression and that area without short
scale-like hairs; subbasal elbow of scapes evenly rounded and not
angled; pronotal dorsum smooth or faintly shagreened; TL 1.7-1.8 mm;
dark yellow brown, extremities orange |
West Africa - ninda |
 |
Antenna 6-segmented | . |
| 8 |  Dorsum
of pronotum extremely coarsely sculptured with closely packed strong
rugae or sulci giving a very coarse overall appearance |
9 |
| -- |  Dorsum
of pronotum smooth to densely reticulate-punctate; may have feeble
striate or very fine superficial rugulae |
20 |
| . | Dorsum of pronotum coarsely sculptured | . |
| 9 |  Disc
of postpetiole densely and strongly longitudinally costulate |
10 |
| -- | Disc of postpetiole smooth and unsculptured, or no more than uneven or feebly punctate | 12 |
| 9 |  Head
very long and narrow (CI 54-58), antennal scapes long (SI 73-78); TL
2.4-2.6 mm; medium brown |
Ivory Coast & Ghana - minkara |
| -- | Head shorter and broader (CI > 60), antennal scapes shorter (SI 68-73) | 10 |
| 10 |  Disc
of postpetiole completely surrounded by dense spongiform tissue;
transverse strips complete; pronotum dorsum coarsely longitudinally
rugose; TL 2.4 mm; dark blackish-brown |
West Africa - enkara |
| -- |  Disc
of postpetiole with dense spongiform tissue only posteriorly and
posterolaterally; transverse strips interrupted medially; pronotum
dorsum irregularly reticulo-rugose; TL 2.4-2.6 mm; medium brown |
Tanzania & Zimbabwe - nykara |
| 12 |  With
alitrunk in profile metanotal groove distinctly impressed |
13 |
| -- |  With
alitrunk in profile metanotal groove not impressed, dorsal outline
continuous |
15 |
| 13 |  Posterior
spongiform margin of postpetiole medially very deeply indented and
reaching the margin of the disc; TL 3.0 mm; medium brown |
weberi |
| -- |  Posterior
spongiform margin of postpetiole medially very shallowly indented,
clearly not reaching margin of disc |
14 |
| 14 | Dorsum of head with hairs strongly forward-arched so as to almost or actually touch surface; TL 2.6 mm; brown | Cameroun - mekaha |
| -- |  Dorsum
of head, especially posterior half, with hairs which have the basal half
to two-thirds erect then apices sharply angled forward; TL 2.5-2.6 mm;
dark brown |
Cameroun - kerasma |
| 15 |
 Dorsum
of head behind clypeus with only fine soft looped or arched simple
hairs; TL 2.1 mm; orange-brown, gaster blackish-brown |
Nigeria and Congo
Basin - malaplax and Zaïre - piliversa |
| -- | Dorsum of head behind clypeus usually with fine hairs plus long, stout conspicuous hairs similar to those on the clypeal dorsum | 16 |
| 16 |  In
profile the longest hairs on the clypeal dorsum (the rear-most row) no
more than half the length of the hairs situated on the dorsum of head
just behind the level of the eyes; TL 2.0-2.1 mm; medium-brown, gaster
blackish-brown |
Cameroun - placora |
| -- | In profile both such sets of hairs of a similar length | 17 |
| 17 | Posterior spongiform strip of petiole very large, obviously densely spongiform not lamellar, thickness in dorsal view greater the exposed length of petiole node; TL 2.6-2.6 mm; dull yellowish-brown or lighter | Cameroun - arahana |
| -- | Posterior spongiform strip of petiole narrow and lamellar, thickness clearly less than exposed length of petiole node | 18 |
| 18 | In posterior view head with long hairs seen as distinctly swollen apically, increasing in width from base to apex; TL 2.3 mm; medium- brown, gaster blackish | Angola - fenkara |
| -- | In posterior view head with long hairs of uniform width throughout their length | 19 |
| 19 | Median indentation in posterior margin of spongiform strip of postpetiole not reaching sclerotised portion of disc; HW 0.50; TL 2.7-2.8 mm; dark brown, gaster blackish | Gabon - synkara |
| -- | Median indentation in posterior margin of spongiform strip of postpetiole reaching sclerotised portion of disc; TL 2.1 mm; brown | Cameroun - tolomyla |
|
Dorsum of pronotum smooth or densely reticulo-punctate | . |
| 20 |  Pronotal
humeri each with a long flagellate hair, the pronotum dorsum with a
median ridge; leading edges of scapes without anteriorly projecting long
hairs; anterior clypeal margin convex and lacking a lateral fringe of
spatulate hairs |
21 |
 Pronotal
humeri without long flagellate hairs, the pronotum dorsum without a
median ridge; leading edges of scapes with anteriorly projecting long
hairs; anterior clypeal margin straight to concave and with a continuous
fringe of spatulate hairs |
23 | |
| 21 |  In
profile clypeal dorsum without hairs; in full face view anterior clypeal
margin broadly convex; sides of clypeus near parallel; TL 2.1-2.3 mm;
glossy light brown |
Zimbabwe - rusta |
| -- | In profile clypeal dorsum with weakly clavate posteriorly curved hairs hairs; in full face view anterior clypeal margin narrowly convex; sides of clypeus forming a line with the mandibles | 22 |
| 22 |  Elongated
hairs on gaster restricted to a transverse row of four close to the
base; flagellate hairs absent from upper scrobe margins; TL 1.9 mm; dull
glossy yellow |
South Africa - anarta |
| -- |  Elongated
hairs on gaster numerbering 12 or more and not confined to close to the
base; 2-3 flagellate hairs on each upper scrobe margin; TL 1.9-2.1 mm;
glossy medium brown |
South Africa & Lesotho - oxysma |
| 23 |  Mandibles
with 16-17 teeth of which the 7th or 8th from the base is by far the
largest; TL 2.5-2.6 mm; black |
Cameroun - terroni |
| -- | Mandibles with 12 teeth of which one of the basal row of five is the largest | 24 |
| 24 |  In
full-face view the head with entire dorsum with large flattened, very
broadly scale-like to suborbicular hairs |
25 |
| -- | In full-face view head without such hairs, or if present the hairs in one or two clear transverse bands | 26 |
| 25 | Postpetiole and first gastral tergite with erect hairs, CI 63-67, no or few scale-like hairs on disc of postpetiole; TL 1.9-2.1 mm; medium to light brown | West Africa & Congo Basin - cavinasis |
| -- |  Postpetiole
and first gastral tergite without erect hairs, CI 56-63, scale-like
hairs sparse but obvious on disc of postpetiole; TL 2.0-2.2 mm; medium
to dark brown |
West Africa - sharra |
| 26 | First gastral tergite without standing hairs | 27 |
| -- | First gastral tergite with standing hairs numerous, or at least single basal and apical pairs | 28 |
| 27 |  Dorsum
of head with a transverse band of broadly scale-like to suborbicular
hairs just forward of occipital margin; TL 2.1 mm; |
Ghana - chyatha |
| -- |  Dorsum
of head without hairs other than fringe around clypeal margin; TL
2.1-2.2 mm; uniform light brown |
Ivory Coast - impidora |
| 28 |  Base
of first gastral tergite sharply impressed medially, sclerite with a
dented appearance, scapes relatively long (SI 72-80); TL 2.4-2.8 mm;
yellow to medium brown, gaster may be darker |
sub-Saharan Africa - emarginata |
| -- | Base of first gastral tergite not impressed medially, scapes shorter (SI 58-67) | 29 |
| 29 |  Pronotal
disc glassy smooth between widely scattered small punctures; TL 2.2-2.3
mm; light glossy brown |
Rwanda - gatuda |
| -- | Pronotal disc uniformly closely sculptured, subopaque to opaque | 30 |
| 30 |  Dorsum
of head with a transverse band of broadly scale-like hairs just forward
of occipital margin plus another just behind the level of the frontal
lobes; TL 2.5 mm; light brown |
Cameroun - behasyla |
| -- | Dorsum of head without two bands of scale-like hairs | 31 |
| 31 |  In
full face view head with conspicuous projecting hairs behind the level
of the eyes |
32 |
| -- |  In
full face view head without conspicuous projecting hairs behind the
level of the eyes |
34 |
| 32 |  Anterior
clypeal margin transverse; dorsal alitrunk with 6-7 pairs of erect
hairs; TL 2.0-2.1 mm; uniform dull yellow |
West Africa & Congo Basin - hensekta |
| -- |  Anterior
clypeal margin concave; dorsal alitrunk with 1-2 pairs of erect hairs |
33 |
|---|---|---|
| 33 | Pronotum dorsum finely longitudinally rugose; TL 2.1 mm; dull yellow to light yellowish-brown | Cameroun - dendexa |
| -- | Pronotum dorsum punctate; TL 2.4-3.0 mm; dull yellow to light yellowish-brown | East Africa - truncatidens |
| 34 |  Postpetiole
dorsum finely longitudinally costulate; infradental lamella of propodeum
reduced to a simple flange; TL 2.6-2.7 mm; dark brown |
Rwanda - datissa |
| -- |  Postpetiole
dorsum wholly smooth; infradental lamella of propodeum broad and
conspicuous; basal lamella of mandible an evenly rounded broad lobe; TL
2.2-2.4 mm; dark brown to blackish-brown |
South Africa - transversa |
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MYRMICINAE Introduction | © 2007 - Brian Taylor CBiol
FIBiol FRES 11, Grazingfield, Wilford, Nottingham, NG11 7FN, U.K. |
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