Engramma, Forel

Wheeler, W. M., 1922, The ants collected by the American Museum Congo Expedition., Bulletin of the American Museum of Natural History 45, pp. 39-269 : 200-202

Engramma Forel

Closely related to Tapinoma ..

Worker 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 frontal carinae. Maxillary palpi 4-jointed; labial palpi 3-jointed. Antennae 12-jointed, 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.

Female larger than the worker; its fore wings with a discoidal, one cubital and a closed radial cell.

Male as small as the worker, with 4-jointed labial and 5-jointed maxillary palpi. Antennae long, filiform, 13-jointed, the scape as long as the first and second funicular joints together. Mandibles large, denticulate, decussating. Mesonotum not overarching the pronotum. Wings as in the female.

This genus has been known only since 1910 and comprises six described species. It has a very narrow range, being confined to equatorial Africa and in all probability to the forest regions (Map 31). Most of the species evidently live in the cavities of myrmecophytes. At least one, however, lives in the ground ( wolfi ) and another, zimmeri subspecies okiavoensis of the Congo, is said to inhabit "a large pale gray nest, soft, woven and mixed with fine vegetable matter and applied to the trunk of a tree."

The workers of the previously known and of three new species described below may be separated by means of the following table.

1. Mesoepinotal constriction very deep and long, so that the thorax is halteriform; epinotum with a pair of denticles above........ denticulatum , new species.

Mesoepinotal constriction only moderately deep, acute; epinotum without denticles..........................................................2.

2. Body long and slender; head and thorax opaque; antennal scapes extending at least one-fifth their length beyond the occipital border................3.

Body more thickset; head and thorax shining; antennal scapes shorter......4.

3. Scapes surpassing the occiput by one-fifth their length; clypeal notch very large and deep and the median border behind it with a small triangular impression; all the funicular joints twice as long as broad; color black, with brown appendages............................................. wolfi Forel.

Scapes surpassing the occiput by about one-fourth their length; clypeal notch broad and shallow, the median border without an impression; funicular joints shorter; color yellowish red, gaster black, its segments narrowly bordered with yellow.................................. zimmeri Forel.

4. Eyes very large, nearly one-third as long as the sides of the head... ilgi Forel.

Eyes much smaller...................................................5.

5. Head, without the mandibles, as broad as long, deeply excavated behind......6.

Head longer than broad, feebly excavated behind........................8.

6. Antennal scapes slightly surpassing the occipital border; funicular joints 2 to

7 slightly longer than broad; base of epinotum nearly as long as the declivity, horizontal; pilosity well developed........................ lujae Forel.

Antennal scapes not reaching the occipital border; funicular joints 2 to 7 broader than long; base of epinotum much shorter than the declivity, sloping forward; pilosity less abundant...................................7.

7. Brown; length 2.25 to 3 mm.............................laurenti Emery.

Dull yellow, with brown gaster; smaller, length 1.8 to 2.2 mm..... kohli Forel.

8. Antennal scapes reaching the occipital border; funicular joints 2 to 7 broader than long; epinotum evenly rounded, without distinct base and declivity. griseopubens , new species.

Antennal scapes extending about one-sixth their length beyond the occipital border; funicular joints all distinctly longer than broad; epinotum with short base sloping forward and long, flat declivity, sloping backward. gowdeyi , new species.