The Ants of Africa
Genus Dorylus - Subgenus Anomma

Dorylus (Anomma) wilverthi Emery

ARCENS group - characterised by the large head, very bulbous in profile and trapezoidal in full-face view.

Dorylus (Anomma) wilverthi Emery

return to key Male return to key {link to the Hymenoptera Name Server} Type locality Za´re (Dorylus (Anomma) Wilverthi n. sp., Emery, 1899e: 459, illustrated, worker; also in Emery, 1901c; Forel, 1909b: 51, male) from Kinshasa [Leopoldville], collected by Wilwerth - see below
junior synonyms
nigritarsis (Dorylys nigritarsis n. ad. int., Strand, 1911: 118, queen) from Cameroun, collected by Carl Feldman at Mowange near Bibundi - no images on Antweb (July 2014)
nomadas (Dorylus (Anomma) nomadas, n.sp., Santschi, 1935a: 254, queen, illustrated, synonymy by Raignier & van Boven, 1955) from Za´re - see http://www.antweb.org/specimenImages.do?code=rmcaent000017713
sjostedtiwilverthi (Anomma Sj§stedti Em. var Sj§stedti-Wilverthi, Wasmann, 1916: 136, no description; 1917: 305, worker; no proper description; new synonymy, see below) from Cameroun - no images on Antweb (July 2014)
all forms known (see Bolton, 1995) .


{Dorylus (Anomma) wilverthi}Emery's (1899e) description is at {original description}; Emery's (1901c) illustrated description is at {original description}; Strand's (1911) description of the nigritarsis queen is at {original description}. A set of illustrations of the queen and workers by Forel (1912j) is at {original description}; Santschi's (1935a) illustrated description of nomadas (queen) is at {original description}.

Emery's description was quoted in full by Raignier & van Boven, 1955). My summary translation is - "Head, vis-a-vis arcens, less elongated, sides less arcuate and the posterior angles each prolonged into a raised point, slightly recurved outwards; these points are present in all morphs but are strongest in the media. Posterior of head deeply scalloped in an arc. The elongation of the head is especially remarkable in the small examples which have the same modifications of the clypeus and pubescence of all the Anomma".

Forel (1909b) describing a male collected by M. Luja in company with "A. wilwerthi" workers, had - TL 26-30 mm, more red and larger than that of nigricans, with longer and narrower mandibles; the vertex also is a little more "bombÚ" - bulging or convex.


{dorylus wilverthi}I have to say that I am baffled by the notes and illustration in Emery (1901c) of what he reported as minima morphs with TL 3 mm and 9 antennal segments and TL 2.5 mm and 8 antennal segments respectively. Among the various species I have seen and photographed, there does not appear to be any minima with less than 11 segments to the antenna. Emery gave no collection details and it seems possible that the single specimen of each morph are "contaminants", perhaps being Dorylus (Alaopone) antinorii - as shown by Emery himself (1881a) but transferred by me to Alaopone.

Wheeler (1922) had full-face illustrations of the head of the soldier and a minor worker, showing the characteristic elongated and divergent posterior corners of the head (right, drawing apparently somewhat exaggerated).


{short description of image}Also from Ivory Coast, at Ouossou (Talbot, in Wheeler, 1922). Forel (1909b) reported workers from Kinshasa [Leopoldville] by Lamarche, and Iringui by Lindemans. He also noted a male, TL 26-30; from Mobeka, by Lothaire, being redder and larger than that of nigricans, with the mandibles slightly longer and straighter, also the vertex slightly more convex, bulging, the specimen was found with workers of "wilwerthi". Bolton (1995) notes that the name is frequently misspelt as wilwerthi but the real error seems to lie in a misspelling, by Emery (1899)?, of the name of the collector who seems definitely to have been Wilwerth; although later in his paper, Forel (1909b) writes of "Plagiolepis fallax" as collected by E. Wilverth. Towards the end of the same paper, Forel, notes how, in August 1907, Luja collected the male with workers on the same army, providing confirmation that his (Forel) description of the male was correct.

It appears to be a forest species, commonest or even restricted to areas of relatively low insolation, which gives for great geographical scope in the Congo Basin, etc.Raignier & van Boven (1955) found it to be by far the most common Anomma species at Yangambi in Za´re; making 26 collections, from 19 nests, with a total of 568 individuals. Their photographs of the head of the major morph are shown below right.

Although they also reported two collections of sjostedtiwilverthi, I suspect from the notes they give of the colonies being mixed, with predominantly normal wilverthi specimens but a relatively small number with reduced or absent teeth on the posterior corners of the head, that what happens is that their findings, and the single finding reported by Wasmann (from Grand Batanga, Cameroon), represent no more than aberrant individuals of a standard wilverthi colony.

Wasmann himself (1916: 136) simply noted - "Ein exemplar lag vor, von Geo Schwab bie Gro▀-Batang in Kamerun 11.7.1912 in einem Zuge von Anomma sj÷stedti Em. var. Sj÷stedti-Wilverthi (einer ▄bergangsform zwischen diesen beiden Rassen) gefangen. Ich bennene die Art zu Ehren des Entdeckers".

Of course, one cannot rule out the occurrence of a hybrid "species". Bolton (1995) has - "Subspecies of nigricans: current status" without giving any authority.


{link to Ants of Congo plates}
A series of worker sizes is illustrated in Schneirla (1971, page 25), as ranging from TL 11.2 mm down to 3 mm. The queen may be TL 52 mm, and lay some 1-2,000,000 eggs in her lifetime. The same author (largely extracting from Raignier & van Boven, 1955) described the colony size as 10-20 million, with a single queen. The nest was said to be within 1-2 m below ground, often under the roots of trees with a central mass. (see illustrations from Wheeler, 1992, "click" left"). Raiding takes place at dusk, less often at dawn and never at midday. Emigration took place most frequently every 25 days or so, although a stay could be as long as fifty days. The average of 26 migrating columns showed a travel of 226 m, said to be the longest of all dorylines, with the movement time averaging 34-38 hours, up to 57 hours in duration. The effect of the movement results in a trench of notable depth, effectively keeping the column below ground.

Raignier & van Boven (1955) have full descriptions of the worker major, male and queen; with specimens of all from within one nest and so definitively associated, unique (at least when they wrote) for all known species of Anomma. They included photographs (monochrome) of the male and female and these are reproduced here.


{Dorylus wilverthi}Full description of major worker (translated from Raignier & van Boven, 1955)
Overall - head brown-black; mandibles, antennae and clypeus red-brown; thorax, petiole and gaster red to red-brown; subpetiolar process dark brown-black; gaster with black areas.
TL 12.38 HL 3.72 HW 3.64 HD 2.60 CI 98 SL 2.04 SI 55 AL 4.11 PW? PetL 1.13 PetW 0.92 GL? MFL ?
Head - widest at anterior; posterior border scalloped, posterior angles extended and with a small lateral turned tooth (characteristic of the species); median line a somber suture on the occiput, becoming a small groove on the vertex; occiput, vertex and front shiny, @ 50 X light reticulation is visible with very sparse puncturation; clypeal margin recurved, with several long hairs, central hairs five times longer than others; mandible slender and with apical tooth; basal tooth set just behind the midpoint, no subapical teeth but internal border crenulated and with hairs, external border glabrous and very finely reticulate; central notch small but visible between frontal carinae and vertex; scape slender (width about 1/8 of length) and slightly curved, finely spiculated (recouvert de rÚticules chitineux) and with fine pilosity, apex enlarged with several erect hairs; funiculus punctuate all over and with tiny erect hairs, segment 2 slightly shorter than 1; 3-5 equisized, slightly longer than 6-9, 10 a club more than twice length of 9; in profile height 70% of length.
Alitrunk - from above much narrower than the head; finely puncturate; metanotal groove distinct but mesonotum barely distinguishable from the propodeum; towards outer edge of propodeum there is a feeble depression giving rise to divergent edges of the declivity; in profile metanotal groove sharp, pronotum slightly above mesonotum; spiracle large; metanotal gland with prominent upper flange terminating in a tooth.
Petiole - from above narrowed anteriorly, longer than wide, puncturate and with several hairs, posteroventral processes small (but not a consistent feature among colonies); laterally height about 60% of length, spiracle well developed and raised; subpetiolar process "scyphiforme" (variable in form and not a reliable diagnostic character) with long hairs.
Gaster - five segmented, overall shape oval; terminal borders with long hairs; basal half of first segment glabrous and shiny; sternites with long hairs.
Legs - coxae finely puncturate; femora glabrous but with golden pubescence; same on tibiae; tarsi with oblique erect hairs; total length of hind legs 13.86 mm.


{Dorylus (Anomma) wilverthi major)The photomontage is of the type major worker collated from http://www.antweb.org/specimen.do?name=casent0903692


{Doryl;us (Anomma) wilverthi media)The photomontage is of a type media worker collated from http://www.antweb.org/specimen.do?name=casent0903693


Oxford University Museum specimens

Dorylus (Anomma) wilverthi
B Taylor det.
Male

Central African Republic
P Annoyer


16.vi.1998
Dzanga-Sangha
Bayanga-Lidjombo; U.V. 19h-05h; LAYON PK 21 5.0 RCA
2
{album}
Dorylus (Anomma) wilverthi
B Taylor det.

Uganda
C Hashimoto
0310103

30.x.2003
Kalinzu Forest
0░23'22.7" S
30░5'33.3" E

6
{album}
Dorylus (Anomma) wilverthi
B Taylor det.

Uganda
S Uehara
III-85

19.xi.2002
Kalinzu Forest
0░23'22.7" S
30░5'33.3" E
In forest
1

Dorylus (Anomma) wilverthi
B Taylor det.
Uganda
S Uehara
III-99
19.xi.2002
Kalinzu Forest
0░23'22.7" S
30░5'33.3" E
In forest
3

Dorylus (Anomma) wilverthi
B Taylor det.
Uganda
S Uehara
III-137

23.xi.2002
Kalinzu Forest
0░23'22.7" S
30░5'33.3" E
Sawmill, in forest
4


{Dorylus wilverthi polymorphism}Polymorphism

In October 2003, Professor Shigeo Uehara sent me three samples of wilverthi from the Kalinzu Forest, Uganda, these were - III-85, of 19.xi.2002, W. of 519, in forest; III-89, of 19.xi.2002, W. of 430 (T4), in forest; III-137, of 23.xi.2002, Sawmill, in forest. From those I was able to create this polymorphism montage and the other photomontages. What is unusual is that the all the morphs, even the very smallest, have the posteriorly narrowed head, with distinct dorsolateral points.

The various morphs are shown in detail on the Dorylus (Anomma) wilverthi page. Other specimens from Cameroun also are shown.


{Dorylus wilverthi sexual stages}Sexual stages - Forel (1909b) describing a male collected by M. Luja in company with "A. wilwerthi" workers, had - TL 26-30 mm, more red and larger than that of nigricans, with longer and narrower mandibles; the vertex also is a little more "bombÚ" - bulging or convex.

A set of images of fresh males and the Forel (1912) "type" queen can be seen on the linked page D. wilverthi males.

Contents
ę 2007, 2008, 2010, 2012 - Brian Taylor CBiol FSB FRES
11, Grazingfield, Wilford, Nottingham, NG11 7FN, U.K.

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