Myrmicaria congolensis Forel - new status

Type location Zaïre (Myrmicaria eumenoides Gerst. v. congolensis n. var., Forel, 1909b: 59, worker; Forel, 1913h: 354, male; Santschi, 1925c: 150, queen - see below
junior synonyms (here)
crucheti (Myrmicaria eumenoides Gerst. stirps congolensis For. Crucheti n. var. , Santschi, 1913c: 311; Santschi, 1925c: 151, worker & queen) from Angola, Benguela, Cucala, J Cruchet - see below
obscuripes (Myrmicaria opaciventris Em. v. obscuripes n.v., Santschi, 1937a: 57, worker) from Zaïre, collector Goffat - see below (label has name "obscuriventris")

(see Bolton, 1995) .

M. congolensis was a stirps/subpsecies of eumenoides in Santschi (1914b: 115) and Santschi (1914d: 342). This was changed to a subspecies of natalensis by Emery (1922e: 123) and then to a subspecies of opaciventris by Santschi (1925c: 149; 1937b: 101). Assuming the description and illustration of the pedicel of Myrmicaria opaciventris given by Emery (1893e) is accurate, it is clear that Santschi (1925c) erred in placing congolensis under opaciventris. Accordingly, I have raised congolensis, as represented by the specimens photographed here, to species status.

Forel's (1909b) description of congolensis is at . Stitz's (1910) description of nitida is at . Santschi's (1913c) description of crucheti is at . Santschi's (1937a: 57) description of obscuripes is at .

The photomontage of the type worker is collated from http://www.antweb.org/specimen.do?name=casent0908332.

Type form

Santschi's (1925c) description of the congolensis type, which follows, shows there to be variability between the larger workers (majors) and smaller minors in details of sculpturation.
WORKER - TL 5.5-7.7 mm. Yellowish red-brown. Antennae, tarsi and gaster red-brown, rest of legs and pedicel lighter. Central area of head more densely longitudinally striated than natalensis (with 10-13 striae between the frontal carinae. Transverse ridge of the vertex very sinuous forming a W-shaped anastomosis. Occipitum with 20-24 striae. Scape area more strongly rugose and the sides of the head without smooth spaces. Median carina of pronotum traversed in the anterior portion or up to the anterior two-thirds by arcuate collateral rugae. Mesonotal dorsum with 12 rugae in the majors and 5 in the smallest workers with a few reaching onto the declivity, but without a ridge separating the dorsum and declivity. Propodeal dorsum also longitudinally striate, more densely in majors. Sides of alitrunk with regular longitudinal striations and no smooth spaces. Pedicel nodes with fine rugae in the majors, nodes in minors smooth. Dorsum of gaster entirely matt in majors; matt forward but smooth and shiny posteriorly in minors. Inter-rugal spaces variable from shiny in minors to matt in majors. Scapes and tibiae striated. Erect pilosity distributed as in natalensis.

Comparisons with natalensis - overall shape similar; but sides of head somewhat more convex; frontal area more distinct; mandible with 4-5 teeth; pronotum dorsum a little flatter; promesonotal suture strongly distinct; propodeum more strongly carinate; mesonotal lobes raised in profile; propodeal dorsum half to two-thirds longer than wide, slightly concave anteriorly; propodeal spines a little stronger and directed downwards more obviously; pedicel of petiole more slender; petiole node a little lower, with the anterior and posterior borders less symmetric; postpetiole with a shorter base, slightly higher, anterior face oblique but less so than striata. Forel (1909b) noted the postpetiole ventral process in congolensis is rectangular, longitudinal and translucent (that of natalensis, eumenoides is an obtuse tubercle, see illustration above).

Santschi noted that Wheeler had cited this form from several localities in Zaïre. He, having regard to the rich supply of specimens from numerous points of the regions (I guess he means the Congo Basin), felt that the type form was not widely represented. The type location was localized in the Benguela area of Angola and shared its habitat with the equally abundant opaca Santschi of Atopomyrmex mocquerysi. These forms of the two species shared remarkable and distinct characters of colour and sculpture. Santschi posed the question - was it mere coincidence or were they subject to a special pressure from the local ecology or was there some unknown biological affinity between them?
Santschi also gave the following key below , in which I retain opaciventris, as well as continuing from his separation of the subspecies of congolensis; curiously Santschi did not included obscuripes.

junior synonym crucheti (Santschi)

WORKER - Distinguished from congolensis by propodeal spines being straight and fine and by its colour being of a more brownish red, appendages and gaster of darker brown sometimes blackish. Also notably smaller and more thickset.

The photomontage of the crucheti type worker is collated from http://www.antweb.org/specimen.do?name=casent0913050.

Subspecies obscuripes Santschi

WORKER - TL 7-0-9.5 mm; sculpturation more pronounced than in congolensis; propodeal spines straight and horizontal, wide at the base (as with the largest mesonotalis); from above the petiole node is wider than the postpetiole and a little wider than long; rest as mesonotalis but overall darker with the mesonotum concolorous with the rest of the alitrunk and the form stronger; alitrunk darkish red-brown, head usually duller, appendages and pedicel darker red to near black, gaster black, base matt, shiny posteriorly.
Specimens from an unknown Zaïre location (type) and Kenya (from H Donisthorpe) a smaller specimen (Santschi, 1913c).

The photomontage of the obscuripes type worker is collated from http://www.antweb.org/specimen.do?name=casent0913052.

Notes on the descriptions and analysis of Wheeler (1922)
Wheeler (1922), regarded opaciventris and/or congolensis as a subspecies of eumenoides but I have used natalensis where Wheeler used eumenoides. His observations were -:
Neither Forel nor Santschi seems to me to have recognized this form very explicitly. Several years ago I received from the former six workers labelled "Benguela (Buchner)" and, as Emery's ergatotypes bore the same label and were also received from Forel and as my specimens agree perfectly with Emery's description, I feel confident that they are cotypes. Later I received a worker and three dealated females from Gaboon (Staudinger) and, as Emery mentions specimens from the same locality , I believe that I have before me also the female of the true opaciventris.
The workers measure about 5 to 6 mm and are pale ferruginous brown, with the antennae, legs, and gaster more fuscous. The mandibles have oblique 5-toothed blades; the clypeus is carinate. The propodeal spines are rather slender and very slightly bent downward, the base of the propodeum is less concave than in the typical natalensis, the peduncle of the petiole is distinctly shorter and not longer than the node. The petiole and postpetiole nodes are laterally compressed and of the same height, the ventral surface of the postpetiole, unlike that of natalensis, is swollen, and projecting and angular in front. The surface of the head and thorax is somewhat less shining than in natalensis, the rugae on the front, pleurae, pro-, meso- and base of propodeum more sharply and regularly longitudinal and not reticulate. The gaster has the basal half or, in some specimens, the whole surface opaque and densely punctate, whereas it is smooth and shining in typical natalensis. The nodes of the petiole and postpetiole have shining summits and in some specimens the sides of the petiole are also smooth and shining, in others like those of the postpetiole, finely punctate and even feebly longitudinally rugulose. In the female, which measures 13 mm, the petiole and postpetiole are sharply longitudinally rugose, the summit of the former concentrically rugose, the scutellum vermiculately rugose. Emery's description of the male, which I have not seen, includes no mention of characters that would distinguish it from the male of the typical natalensis.
Numerous specimens from the various Congo localities cited above seem to me to be referable to Emery's subspecies, though they differ more or less in the sculpture of the petiole, postpetiole, and gaster and in being mostly of a darker color. They average larger than the specimens of variety congolensis and variety crucheti, the workers being 5 to 6.5 mm. The petiole and postpetiole, especially the latter, are nearly always more or less longitudinally rugulose on the sides, though sometimes merely punctate, as Emery remarks in the original description. The specimens from Walikale have the entire gaster opaque and punctate, whereas in others it is punctate usually only on the anterior half of the first segment. This character, however, varies in individuals from the same colony. Santschi says that the gaster of the worker is "entièrement sculpté, mat, brun clair," but Emery describes the gaster as fuscescent, with the anterior half of the first segment opaque.
In Zaïre, the typical nests observed by Lang were "as a rule built at the bases of trees and bushes, can be easily recognized by the mound of earth thrown up while the chambers are being excavated".

Variety congolensis (Forel). Wheeler noted - This form is not represented among the material collected by Lang, Chapin, and Bequaert. Santschi regards it as an independent subspecies, but it seems to me to be merely a variety of opaciventris. Three cotypes of congolensis were given me by Forel. Comparison of these specimens with opaciventris show relatively slight differences. They are somewhat smaller, of a more sordid yellowish brown color and with much the same sculpture and lower portion of the postpetiole. The propodeal spines, however, are decidedly more slender and more strongly deflected, a character not mentioned in Ford's original description, though noted by Santschi; the head is proportionally smaller and narrower, with straight cheeks, and the gaster is opaque only at the base of the first segment, the remainder being rather shining.

Variety crucheti (Santschi). Wheeler referred numerous specimens (from Zaïre localities) to the variety crucheti since they agree with Santschi's very brief description in size (5 to 5.5 mm) and in having slender but straight propodeal spines. The petiolar node is distinctly broader and less compressed laterally than in the typical natalensis and not shorter than the peduncle. The surface of the petiole is not so smooth, though it is not longitudinally rugulose. I have received this same form in all three phases from Rev. Geo. Schwab, who took it at Metit, Cameroun. The female is very similar to that of the typical natalensis, but the head is somewhat smaller, with slightly more prominent posterior corners and the gaster is entirely opaque and punctate, except the bases of the second and following segments.

Wheeler (1922) listed it (as ssp of eumenoides) from Senegal (Samlia Falls, by Mocquerys), Cameroun (at Mundame by Conradt, and Yaoundé by Zenker), and widely through sub-Saharan Africa. Also as congolensis from Cameroun (Victoria, F. Silvestri), crucheti from Cameroun (Metit, by Rev. Geo. Schwab); and nitida from Cameroun (Douala by Schafer).

Santschi (1925) listed records of - congolensis from numerous Congo Basin localities, Sudan and Cameroun, collected at Molundu by Reichensperger; crucheti from Angola and Zaïre; and mesonotalis from several Congo Basin localities.

Collected at Nko'emvon in Cameroun (D.A. Jackson, identified by B. Bolton) (Jackson, 1984). The second most common ground ant in one of the three cocoa plots studied by Jackson. Collected by pitfall trapping and hand searches, with some 300-700 individuals collected at each of four collection dates. The level of insolation appeared to make a difference, with its numbers being higher in insolated traps. Its main competitor was Pheidole species 2 but the Myrmicaria were better able to handle larger solid food sources.

Referred to as a predator of Camponotus acvapimensis by Lévieux (1983a, as Myrmicaria nitida).

Wheeler noted that in Zaïre, the typical nests observed by Lang were "as a rule built at the bases of trees and bushes, can be easily recognized by the mound of earth thrown up while the chambers are being excavated" (illustrated left and "click").

Oxford University Museum specimens

Myrmicaria congolensis crucheti B Taylor det. Type form	Benin J-F Vayssieres RVA 3092.3	10.xi.2011 Tanquiéta 10°40'05'' N 01°18'14'' E	Acacia hockii beating 234 m asl	5
Myrmicaria congolensis B Taylor det.	Cameroun G Debout & A Dalecky Cameroon 41	5.iv.2001 Nkolobondé 3°14' N 10°15' E	on soil and surface in the village	2
Myrmicaria congolensis B Taylor det.	Cameroun G Debout & A Dalecky Cameroon 44	5.iv.2001 BOU 3°13.31' N 10°15.01' E	on soil & surface in forest understorey	3
Myrmicaria congolensis B Taylor det.	Central African Republic P Annoyer HL	08.x.2008 Dzanga-Sangha	9h50-10h10; 10 kms après Bokoko direction Nola	2

The photomontage is of a worker from the Central African Republic, Dzanga-Sangha NP; collector Philippe Annoyer.

The photomontage is of a worker collected in Cameroun, south-western tropical coastal forest area between Edéa and Campo (McKey Wolbachia project; Cameroon 44).

The photomontage is of a major worker from Benin, Tanquiéta; collector J-F Vayssieres (RVA 3092).