Anochetus bequaerti

Brown, WL Jr.,, 1978, Contributions toward a reclassification of the Formicidae. Part VI. Ponerinae, tribe Ponerini, subtribe Odontomachiti. Section B. Genus Anochetus and bibliography., Studia Entomologica 20, pp. 549-638 : 603-604

[30] A. bequaerti

is an extremely variable species that is closely related to africanus , and shares with it the same fine striation of the vertex reaching from the frontal lobes to the nuchal carina in the middle. Usually the trunk in bequaerti is black or piceous (more rarely red), with more or less coarse sculpture covering all of its dorsal surface. In the holotype, the pronotum is deeply and densely punctulate and opaque, with a few concentric rugulae superimposed around the disc, while in other samples it can be irregularly rugulose-striate (e.g., CNRS Research Station, near Makokou, Gabon, I. Lieberburg, rain forest), or reticulate-rugose, as in the opaciventris syntypes, discussed below, or in specimens from Lamto Field Station, south-central Cote d’Ivoire (J. Lévieux).

The propodeal angles vary, but are often prominent, blunted subacute or sub-rectangular; the summit of the petiolar node as seen from the front is truncate or concave. Gaster brown or piceous, the first 2 terga covered at least over their anterior halves, with fine sculpture, varying from delicate, shallow reticulation to dense, moderately deep punctulation, and from shining to opaque.

Head usually red in color, varying from light yellowish-red, to mahogany with infuscated middle vertex; most often contrasting with darker trunk; mandibles and legs tend to be lighter, more yellowish.

Size ranges from about HL 1.25 to HL 1.75 mm. The larger specimens (HL> 1.50 mm) correspond to the opaciventris phenon.

A syntype worker from Akenge, Zaire (H. O. Lang) has HL 1.73, HW 1.37, ML 1.02, scape L 1.44, eye L 0.25 mm; Cl 79, MI 59. A worker from 39 km S of Walikale, 700 m, Zaire (E. S. Ross and R. E. Leech) measures HL 1.63, HW 1.39, ML 1.04, scape L 1.45, eye L 0.26 mm; Cl 85, MI 64. Other samples agreeing with the opaciventris pattern also come from NE Zaire and the neighboring Imatong Mts. of S Sudan: above Lotti Forest, 1040 m, J. G. Myers. Besides large size and coarse sculpture - especially the opaquely punctulate gastric sculpture - opaciventris workers tend to have very abundant fine standing pilosity on the dorsum of head and trunk (little apparent in the opaciventris types, which were damaged samples taken from toad stomachs), whereas the smaller-sized «typical» bequaerti have only a few (6-20) coarse hairs on the trunk.

I am following the hypothesis that the opaciventris phenon amounts to a localized (central) allometric variant of the species A bequaerti , noting that that species’ size variation (HW 1.25 to 1.75 mm) is not very different from that of africanus workers (HL 1.36 to 1.70 in MCZ material); pilosity variation is paralleled by A. traegaordhi .

The species estus was raised by Wheeler on a single specimen [AMNH-New York] from Akenge, NE Zaire: TL 5.3, HL 1.37, HW 1.22, ML 0.76, WL 1.63 mm; Cl 89, MI 55. The type looks like some of the africanus samples from Cote d’Ivoire, but the gastric dorsum is shallowly reticulate (not as Wheeler described it, "very smooth and shining"). This specimen might be viewed as an intergrade (hybrid?) between africanus and bequaerti , but I believe it is more likely just another variant of bequaerti .

Very noticeable variation also involves the length and width of the mandibles and the size òf the compound eyes. Short mandibles (MI 60 or less) and large eyes (eye L 0.25 or more) seem to go together, and the reverse, and it is possible that a very rough negative correlation exists between these structures. Bolton (personal communication) has suggested a possible sorting of large-eyed samples into savanna habitats and smaller-eyed ones into forest zones, but the available material is equivocal in this point. In view of similar variation in some other Anochetus species and groups, though, it would be worth further study when the samples and ecological data become adequate.

One puzzling variant, very small in size (HL 1.10, HW 1.00, ML 0.67 mm), with relatively large eyes (L 0.25 mm), is testaceous with slightly darker (yellowish-brown) gaster. The vertex is finely striate back to the nuchal carina, and even over all but the postero-lateral parts of the «occipital» lobes, as in many bequaerti workers. The habitus, because of the light color, somewhat recalls pellucidus , but the "translucent look" of the head and mandibles is lacking. The gastric tergum is shining but reticulate over the anterior halves of the first 2 segments.

This anomalous worker could be a hybrid, or an undescribed species, but it is most likely just another manifestation of the extreme variability of'A bequaerti .