|The Ants of Africa
Genus Technomyrmex Mayr
Genus Technomyrmex Mayr (1872: 147)
Diagnostic features - Very similar to Tapinoma but has five gastral segments visible in dorsal view and the anal and associated orifices are apical; petiole node low to nil; propodeum unarmed in dorsal view; propodeal spiracles lateral (but below the dorsum) or ventral.
Smith, F. 1861. Catalogue of hymenopterous insects collected by Mr. A. R. Wallace in the Islands of Ceram, Celebes, Ternate, and Gilolo. J. Proc. Linn. Soc. London Zool., 6, 36-48.
Mayr's (1872: 147) definition of the Genus is at . Arnold (1915: 148) gave a note on the genus, with a key to South African species, this is at . When I started the website there were no modern revisions.
In November 2001, I added the species sent to me from the McKey Wolbachia project in Cameroun, such as ilgi (?) and kohli; other species known from ZaÔre, thus potentially from West Africa; and also a page with material from Wheeler (1922), mainly relating to other species he described as Engramma (all of which seem to fall into a group with the head heart-shaped in full-face view). In 2003, the work of Donat Agosti's project in putting original publications on the internet made it possible to make almost complete comparison of all the named species.
According to Bolton (1995), Shattuck (1991, 1992) removed most Engramma to Technomyrmex, except for those he placed in Axinidris. My feeling is that the Engramma, now Technomyrmex, were orginally separated as having a head which is distinctly heart-shaped in full-face view. Forel's (1905b: 180) definition of Engramma is at and, although rather cursory, gives the key features as:
Maxillary palps 4-segmented, labial palps 3-segmented; clypeus with anterior border deeply excised or scalloped; antennae 12-segmented; head cordiform (heart-shaped); opening of cloaca inferior; petiole with scale welded (soudeť) to the pedicel (as in genus Tapinoma)
Forel also felt the structure of the gizzard was a useful character but that is hardly realistic for field taxonomists.
Wheeler (1922) defined the workers of Engramma as :- Small, monomorphic, with the head more or less excised behind, and the anterior border of the clypeus semicircularly notched in the middle and posteriorly extending back between the short but widely separated carinae. Maxillary palps 4-segmented. Antennae 12-segmented, with long first and last funicular joints. Gizzard with narrow, separated, anchor-like sepals. Gaster large, its first segment overlying the petiole; anus terminal or subterminal. The genus, as thought in 1922, had been known only since 1910 and comprised six described species. It has a very narrow range, being confined to equatorial Africa and in all probability to the forest regions. Most of the species evidently live in the cavities of myrmecophytes. According to Wheeler, at least one, however, lives in the ground (wolfi) and another, zimmeri subspecies okiavoŽnsis of the Congo, had been found inhabiting "a large pale gray nest, soft, woven and mixed with fine vegetable matter and applied to the trunk of a tree." His key is on a separated page at Wheeler (1922) Engramma key.
Snelling (2007) has made a fresh review of the related genus Axinidris. One result is the transfer of the former Technomyrmex hypoclinoides Santschi to the status of Axinidris hypoclinoides.
Bolton (2007) has published a global review of the Genus... He sustains the synonymy of Engramma but made no comments on the separation of species by the structure on the clypeus - writing (p 5) "Median portion of anterior clypeal margin transverse to very deeply incised". In his definition of species groups the form of the clypeal margin tends to be uniform in most groups. In Africa he has only one group, the textor group, which has "a shallow median concavity to a deep median incision". In that group, three members are very similar but the fourth (T. rusticus) is quite distinct
I find Bolton's key rather difficult to use, not least because it concentrated on the presence and position of erect hairs or setae. Bolton himself prefaces his key by noting that setae are relatively easily rubbed off or lost in life.
Thus, I am sticking [November 2007] with a primary separation into those with a distinct, often deep median notch to the clypeus [Technomyrmex (Engramma)] and those without such a notch [Technomyrmex (Technomyrmex)]. It should be noted that, apart from recognizing the earlier synonym by Shattuck (1992b), Bolton does not comment on this old subgenus situation. Instead as in his other works, Bolton creates so-called species-groups.
Of the pre-existing African species, Bolton has synonymized a number and added several new species as follows:
Key to African species of Technomyrmex - incorporating amendments and new species from Bolton (2007).
|© 2007, 2008, 2009, 2010 - Brian Taylor CBiol
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