The Ants of Africa
Genus Myrmicaria
Myrmicaria exigua André

Myrmicaria exigua André

return to key {link to the Hymenoptera Name Server} 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 (Myrmicaria 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
obscura (Myrmicaria exigua André v. obscura n. var., Santschi, 1920c: 120, worker) workers from Zaïre by Bequaert and Congo by Kohl - see http://www.antweb.org/specimenImages.do?code=casent0913038
pulla (Myrmicaria exigua André var. pulla n. var., Santschi, 1920c: 119, queen) workers, two locations, Bequaert and Gerard - see http://www.antweb.org/specimenImages.do?code=casent0913039
rufiventris (Myrmicaria 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 {original description}. Stiz's (1910) description of gracilis is at {original description}. Forel (1910e: 445) gave a full description of gracilis, this is at {original description}. Forel's (1915c) description of rufiventris is at {original description}. Santschi's (1920c) descriptions of pulla and obscura are at {original description}.


{Myrmicaria exigua}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 -
Myrmicaria exigua funiculus 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.
Myrmicaria exigua pedicelThe 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 anterior corners.
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.

1 Colour pale yellow-brown or reddish-yellow 2
-- Colour dark brown to black 3
2 Gaster concolourous or slightly darker; TL 3.5-4.3 mm (Sierra Leone) M. exigua André
-- Gaster lighter, reddish-yellow, sometimes head a little browner (Zaïre) var rufiventris Forel
3 Black, articulations of petiole brownish, TL 3.8-4 mm (Zaïre) var pulla Santschi
-- In part black and lighter brown 4
4 Propodeal spines a little longer than their width apart; body (dark) brown, gaster black; petiole narrower (Cameroun) var gracilis Stitz
-- Propodeal spines shorter than their width apart, gaster as light or lighter than head 5
5 Matt, petiole as with gracilis (Cameroun) var simplex Stitz
-- Shining, petiole larger 6
6 Reddish-brown, head often a little darker; mesonotal angles feebly lobed or tuberculous, declivity oblique (Zaïre and Congo) var obscura Santschi
-- Head blackish, thorax variable brown, gaster often lighter; mesonotal angles distinctly lobed, declivity near vertical (Zaïre) var kisangani Wheeler

Oxford University Museum specimens

Myrmicaria exigua
B Taylor det.
Cameroun
G Debout & A Dalecky
Cameroon 105
24.iv.2001
JFK
3°13.53' N
10°15.07' E
at extrafloral nectaries of a shrub in a treefall gap 2
{album}
Myrmicaria exigua
B Taylor det.
Rep. of Congo
D De Bakker & JP Michiels
ex Y Braet
18.ix.2007
Mayombe
05°37'16" S
13°05'54" E
266 m asl
Canopy fogging

6
{album}
Myrmicaria exigua
B Taylor det.
Male
Central African Republic
P Annoyer
IB
13.x.2008
Dzanga-Sangha
03°03'58.3" N
16°08'59.6" E
528 m; Camp 1; 17h30-3h; A la base de l'Ayous (Triplochiton scleroxylon, Sterculiaceae) à 50 m du Camp
1
{album}
Myrmicaria exigua
B Taylor det.
Male
Central African Republic
P Annoyer
IT
15.x.2008
Dzanga-Sangha
03°03'58.3" N
16°08'59.6" E
528 m; Camp 1; 18h-24h; A 20 m de l'Ayous (Triplochiton scleroxylon, Sterculiaceae) dans la forêt
1
{album}

{Myrmicaria exigua} The photomontage is of a worker from Congo, Mayombe; collectors D De Bakke & J P Michiels. Close to the type form.


{Myrmicaria exigua} The 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.


{Myrmicaria exigua male}The photomontage is of a male from the Central African Republic, Dzanga-Sangha NP; Camp 1; collector Philippe Annoyer.

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© 2007, 2008, 2009, 2012, 2014, 2016 - Brian Taylor CBiol FRSB FRES
11, Grazingfield, Wilford, Nottingham, NG11 7FN, U.K.

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