THE SOLDIERLESS TERMITES OF AFRICA 159 



an easily ruptured gut might be an advantageous adjunct of a dehiscent abdomen 

 as a suicidal defence mechanism. The abdomen certainly appears to be dehiscent 

 to a very marked extent in all species of Ateuchotermes. However, in the narrow 

 tunnels and crannies of their habitat the muscular contortions of their movements 

 might set off the mechanism prematurely, and it could well be that this development 

 took place to counteract the over-developed suicidal tendency. The connection 

 would also tend to rupture more abruptly under the hydrostatic pressure, resulting 

 in a more effective defensive explosion. Whatever its function, this structure 

 provides a set of extremely valuable taxonomic characters. The spines on cushions 

 in positions 2, 3 and 4 are clearly a development of the simple backwardly directed 

 non-return mechanism seen in many other genera. In some species they appear 

 to be capable of forming a filtering network held together by hooks at their tips. 

 Within the genus Atettchotermes these structures form a sequence of developing 

 elaboration. A further species is known in which all cushion positions are developed 

 to about the same extent, and like positions 2, 3 and 4. This would seem to indicate 

 a relationship with other genera such as Apagotermes and possibly Amicotermes. 

 The enteric valve of this species is included in the illustrations of the genus to show 

 the relationship, but since only the worker caste is available it is not described or 

 included in keys (PI. 4, figs 3 & 4). 



Ateuchotermes is one of the more compact and well-defined genera in the cluster 

 and vector analyses (Text-fig. 402) of the similarity matrix. In both single linkage 

 and median sorting the group forms above the 80% phenon level, 86% in the case 

 of single linkage and joins with related groups at the 75-78% level. Genera placed 

 close to Ateuchotermes in some eigenvectors of the principal co-ordinates analysis, 

 as well as the cluster analyses, are Alyscotermes, Anaorotermes, Acholotermes. Amico- 

 termes and Aderitotermes. Because the enteric valve of Ateuchotermes workers is 

 so distinctive, there is no need to compare this caste to related genera. In the imago, 

 Alyscotermes is distinguished by its rather regularly oval fontanelle; in Ateucho- 

 termes this is never very clearly defined, and if nearly oval, is very small and in- 

 distinct. Anaorotermes, Acholotermes and Amicotermes have uneven pilosity, 

 and the two latter genera, longer apical mandibular teeth. Aderitotermes has a 

 sharply defined, pale coloured fontanelle. One species of Ateuchotermes keys out 

 next to Adynatotermes but is smaller with larger eyes and ocelli and less inflated 

 postclypeus. Certain species of Astratotermes, in particular A. pacatus, are very 

 difficult to distinguish from one or two Ateuchotermes in which the fontanelle ap- 

 proaches oval shape. In A. pacatus the outline of the fontanelle has a tendency to 

 be indistinct in some specimens, and there is no other character that can be used to 

 separate it in the imago. Measurement characters provided no clear generic 

 discrimination in either caste as shown by the canonical variates analyses in Text- 

 figs 400 & 401. 



Key to Species 

 Imagos 



1 Compound eyes and ocelli large, W/E, 3-26-3-58, O w /0-E, 2-27-5-60 (i.e. separated 



by less than half least diameter of ocellus) ....... 2 



