Myrmicaria exigua André
Type location Sierra
Leone (Myrmicaria exigua
n. sp., André, 1890: 320, worker & male) 5 workers & male
collected by Mocquerys - see below
junior synonyms (here)
gracilis n. sp., Stitz, 1910: 133, worker; synonymy Santschi,
1920c: 119) from Cameroun,
workers, from Bibundi, by Tessmann - see http://www.antweb.org/specimenImages.do?code=casent0908328
kisangani (Wheeler, 1922: 148, workers) from Zaïre
- see http://www.antweb.org/specimenImages.do?code=casent0913037
exigua André v. obscura
n. var., Santschi, 1920c: 120, worker) workers from Zaïre
and Congo by Kohl - see http://www.antweb.org/specimenImages.do?code=casent0913038
exigua André var. pulla
n. var., Santschi, 1920c: 119, queen) queen and workers from Zaïre, two
locations, Bequaert and Gerard - see the non-type worker at http://www.antweb.org/specimenImages.do?code=casent0913039
exigua André v. rufiventris
n. var., Forel, 1915c: 345, worker), four
locations by Kohl, from Zaïre - see http://www.antweb.org/specimenImages.do?code=casent0908327
simplex (Stitz, in Santschi, 1925c: 170, worker)
from Cameroun - see https://www.antweb.org/specimenImages.do?code=focol1592
(see Bolton, 1995) .
André's (1890) description is at . Stiz's (1910) description of gracilis
is at . Forel (1910e: 445) gave a full
description of gracilis, this is at . Forel's (1915c) description of rufiventris
is at . Santschi's (1920c)
descriptions of pulla (queen described) and obscura are at .
The photomontage of a cotype worker is collated from http://www.antweb.org/specimen.do?name=casent0908326.
The type worker can be seen at http://www.antweb.org/specimenImages.do?code=casent0915404
The only African arboreal member of the genus. Wheeler
(1922) also listed the nominal species, TL 3-3.5 mm, from Cameroun (H.
Brauns), and described it as found crawling around the base of an
orange tree at Kisangani [Stanleyville] in Zaïre; noting also that rufiventris
was reported by Kohl (via Forel) as building "carton
nests 3-4 cm in diameter on leaves" (Forel's 1916 record has the nests
as constructed of a tissue like material and not of simple carton). In
his introduction to the genus, he noted that the smaller species in the
Orient also make small carton nests on the underside of leaves.
Bernard (1952) noted that a single worker of the variety
obscura had been collected at Yalanzou, Guinea,
of this sole aboricolous member of the genus, previously the variety
had not been found outside the Congo.
Santschi (1925) had the following description -
Easily distinguished from other African Myrmicaria but very
variable in the characters that serve to define the different forms.
His species sensu strictu description is -
WORKER TL 3.5 - 4.4 mm. Reddish-brown to brownish
yellow; gaster more or less darker. shiny. Head and thorax with
scattered rugae and variably reticulated; similar on the sides of the
head and thorax, variably spaced, often effaced on the central area of
the head, the pronotal dorsum and the upper propodeum. Remainder
smooth. Pale long pilosity abundant on the body and appendages.
Head oval larger to the posterior. Eyes set between the middle and the
hind quarter of the sides of the head. Mandibles striated, with 4
teeth. Clypeus convex and without carinae. Frontal area not very
distinct, rugae sinuous. Antennal scape more than twice the length of
the posterior border of the eye. All funiculus segments longer and more
slender than those of natalensis. Dorsum of pronotum and
anterior mesonotum flat and edged. Lateral angles of pronotum without
denticles. Anterior and posterior faces of the mesonotum separated by a
strong ridge abutted on each side by a small tubercle or rudimentary
lobe. Anterior face of propodeum rectangular, longer than wide, flat
but slightly lower than the level of the mesonotum.
petiole peduncle much longer than the node, with the node less high
than long. The subpetiole face is rounded as in nigra. Petiole
node with very oblique anterior and posterior borders. Viewed from
above it appears about 50-66% wider than the peduncle. The postpetiole
is triangular with a rounded summit of a similar height to the petiole,
the anterior declivity is more oblique than the posterior.
Forel's (1915c) description of rufiventris
TL 3.8-4.6; differing from type solely by its clearer, rust-coloured
gaster; and by the head being a little more elongated and narrower
posteriorly. Specimens came from St. Gabriel, Lumaliza and Batiamponde,
Zaïre, collected by Kohl; found in small, round (3-4 cm diameter)
carton nests built on leaves.
Wheeler's (1922) description of kisangani
WORKER - length 3 to 3.5 mm. Head through the eyes
scarcely longer than broad, evenly rounded behind. Mandibles 4-toothed.
Clypeus ecarinate, convex, with entire, rounded anterior border.
Frontal carinae subparallel. Eyes convex, just behind the middle of the
head. Antennal scapes extending about two-fifths their length beyond
the posterior border of the head; apical funicular joint fusiform,
enlarged as in the typical exigua. Pronotum more flattened
above, though bluntly angular on the sides and without inferior teeth.
Promesonotal suture distinct. Mesonotum with a small but distinct tooth
on each side in front and the posterior lobes larger, erect, and rather
acute. Metanotal groove very distinct and rather long. Propodeum not
longer than broad, scarcely narrowed in front, its base longitudinally
grooved in the middle, marginate on each side and not longer than the
declivity, which is also marginate laterally; spines not longer than
their distance apart at the base, straight, directed backward, upward,
and outward, their tips not bent inward as in the typical exigua.
Petiolar peduncle as long as the node, swollen at the spiracles; node
longer than broad, as high as long, laterally compressed, constricted
behind. Postpetiole longer than broad, broader and higher behind than
in front, its node distinctly lower than that of the petiole. Anterior
border of gaster straight or even slightly concave, with prominent
Shining: mandibles subopaque, longitudinally striate. Clypeus smooth in
the middle, delicately rugulose on the sides. Head smooth in the middle
of the front, delicately and irregularly longitudinally rugulose on the
sides, posteriorly reticulate-rugose, but much less sharply than in the
typical exigua. Pronotum with a few longitudinal rugae, sometimes
absent in the middle line; in some specimens reticulately-rugose over
the whole surface, with very large meshes as in exigua. Sides
of pronotum smooth and shining; meso- and metapleurae subopaque,
longitudinally rugulose. Base of propodeum transversely rugulose,
declivity smooth and shining. Pedicel, gaster, and legs smooth and
shining, with very sparse and minute, piligerous punctures. Pilosity
like that of the typical exigua, grey or whitish. Piceous,
nearly black; tips of mandibles, peduncle of petiole, declivity of
propodeum, base of postpetiole and in some specimens the whole gaster
or only the base of the first segment brown.
Described from numerous specimens taken at Kisangani [Stanleyville],
Zaïre, (Lang & Chapin) "crawling about the base of an orange tree."
I have compared this form with two cotypes from Sierra Leone
(Mocquerys), received many years ago from André, and a worker from
Gaboon (Staudinger). The new subspecies differs in its much darker
color, feebler sculpture, laterally more compressed petiolar node and
in the shape of the mesonotum, which in the typical form of the species
lacks the anterior tooth on each side and has only feeble indications
of the posterior lobes. Forel has described a variety, rufiventris,
from carton nests 3 to 4 cm. in diameter on leaves at St. Gabriel,
Lumaliza, and Batiamponde (Kohl), all localities near Stanleyville.
This form is larger (3.8 to 4.6 mm) and, according to Forel, "differs
from the type of André only in its paler, reddish abdomen and in having
the head more elongate and narrower behind."
Santschi (1925) also gave the following key to the
subspecies of exigua.
The level of variations appears to have no real significance and I feel
they all are junior synonyms. Curiously, the wholly arboreal and
morphologically not too dissimilar species (slender with many hairs and
long propodeal spines) Tetramorium aculeatum also
shows a range of variations.
||Colour pale yellow-brown or
||Colour dark brown to black
||Gaster concolourous or slightly
darker; TL 3.5-4.3 mm (Sierra Leone)
||Gaster lighter, reddish-yellow,
sometimes head a little browner (Zaïre)
||var rufiventris Forel
||Black, articulations of petiole
brownish, TL 3.8-4 mm (Zaïre)
||In part black and lighter brown
||Propodeal spines a little longer than
their width apart; body (dark) brown, gaster black; petiole narrower
||Propodeal spines shorter than their
width apart, gaster as light or lighter than head
||Matt, petiole as with gracilis (Cameroun)
||Shining, petiole larger
||Reddish-brown, head often a little
darker; mesonotal angles feebly lobed or tuberculous, declivity oblique
(Zaïre and Congo)
||Head blackish, thorax variable brown,
gaster often lighter; mesonotal angles distinctly lobed, declivity near
||var kisangani Wheeler
Oxford University Museum
B Taylor det.
G Debout & A Dalecky
nectaries of a shrub in a treefall gap
B Taylor det.
|Rep. of Congo
D De Bakker & JP Michiels
ex Y Braet
|266 m asl
B Taylor det.
|528 m; Camp 1;
17h30-3h; A la base de l'Ayous (Triplochiton
scleroxylon, Sterculiaceae) à 50 m du Camp
B Taylor det.
|528 m; Camp 1;
18h-24h; A 20 m de l'Ayous (Triplochiton
scleroxylon, Sterculiaceae) dans la forêt
photomontage is of a worker from Congo, Mayombe; collectors D
De Bakke & J P Michiels. Close to the type form.
photomontage is of specimens collected in Cameroun -
south-western tropical coastal forest area between Edéa and Campo
(McKey Wolbachia project, Cameroon 105); location JFK
(Joung Forest nr Nkolo - at 3°13.53' N 10°15.07'; flat land, liable to
flooding), 24 April 2001; at extrafloral nectaries of a shrub in a
treefall gap. Although unimportant, the key in Santschi (1925c) leads
to these specimens being of the subspecies gracilis Stitz, in
being brown with a black gaster and the propodeal spines being not much
longer than their basal separation. They also match the type of kisangani. Rather smaller than the
type form and with a rounder head in full face view.
photomontage is of a male from the Central African Republic,
Dzanga-Sangha NP; Camp 1; collector Philippe Annoyer.