Tetramorium dumezi Forel

Type location Zaïre (Tetramorium simillimum Sm. r. isipingense For. v. Dumezi n. var., Forel, 1916: 422; listed as T. simillimum var dumezi by Menozzi, 1942: 177, worker); Bolton (1995: 407) has raised the variety to species and synonymised the material with that he described as dumezi n.sp. (Bolton, 1980). The specimens were referred to by Bequaert (1922, p 407) as collected in myrmecophilous plants by Father H Kohl, from the Kisangani area (originally described by Forel, 1916). Bolton did not give this information .

Forel's (1916) description is at . Found in a myrmecophile plant. All that appears in Menozzi (1942) is - "Tetramorium simillimum var. dumezi FOR." some workers. Bolton's modern description (1980) is at .

WORKER - TL 2.7-3.1 mm (Forel has TL 2.1-2.5 mm, smaller than the type, simillimum, TL 2.0-2.7 mm); smooth mandibles, entire clypeal margin and no standing hairs on the scapes and tibiae. All dorsal surfaces with scattered short straight hairs. Colour clear pale yellow (Bolton, 1980: 346, not illustrated).

Bolton (1980) described his "holotype" and 10 "paratype" workers, from leaf litter at CRIG, Ghana (9.ii.1971). He also listed collections in Ghana at Numia, Bunso and Enchi (D. Leston), Aburi (P.M. Room), and CRIG (C.A. Collingwood and C.A.M. Campbell).

Elsewhere it was known from Nigeria, at IITA (B.R. Critchley), and Zaïre (Bolton, 1980).

If one considers dumezi for which there is no illustration, a quandry arises. After stating he had examined syntype workers of Tetramorium simillimum Sm. r. isipingense For. v. dumezi n. var. Forel (1916: 422) collected by Father H Kohl at St. Gabriel Mission, Congo, Bolton (1980: 346) designated further specimens collected in Ghana by himself, reporting other material from Ghana and Nigeria. Bolton's specimens were TL 2.7-3.1 mm, SI 70-77; whereas Forel gave a TL 2.1-2.5 mm, and said the scape almost reached the occiput. Bolton's Ghana-Nigeria specimens were found in leaf litter; Forel's were found in a myrmecophile plant. Menozzi (1942: 177) reporting ants from Fernando Po and Rio Muni had the record - "Tetramorium simillimum var. dumezi For. Alcune operaie [some workers]".

An answer to what exactly Forel's dumezi was is to back track the thought process he had adopted some forty years earlier. In his first major work on ants, Forel had adopted the curious, if not bizarre, attitude that the practice of Mayr in naming new species was in some way wrong and it was preferable to avoid a proliferation of new "species" by settling rather for giving the name of races to poorly determined species, or one could call them sub-species (Forel, 1874: III). Quite why the third level of variety came into use is not clear.

Forel's dumezi description, therefore, expects one to comprehend the general form of the base species Tetramorium simillimum (as the photograph, right). From that one has to consider Tetramorium isipingense from the Forel (1914d: 225) notes as bigger, TL 2.9-3.1 mm, than the type; head without shallow scrobes and with shorter frontal carinae; the propodeum with smaller teeth generally more elongated and metapleural lobes larger; wholly shiny and with much less dense rugae and reticulation; colour paler - "this form would merit species status if T. simillimum was not so variable". Forel has the rest as the type but does not refer to the sparse, short, blunt hairs found on simillimum. Both have an SI 78-81.

Forel's (1916) dumezi has TL 2.1-2.5 mm; smaller than type of the race (isipingense); propodeal teeth slightly stronger and more distinct; scape shorter, failing to reach the occiput by about 2.5 times its own width; the semi-scrobe and the frontal carinae are notably clearer; the petiole node is a little less rounded; overall slightly more robust; colour darker on the head but lighter on the gaster.

Forel's (1914d) description of Tetramorium isipingense is at . Arnold (1917: 329) gave a translation, this is at . Bolton's modern description (1980), not illustrated, is at . WORKER - TL 3.2-3.3 mm.