THE SOLDIERLESS TERMITES OF AFRICA n 



adaptive importance, and where widely and consistently different is a useful character 

 delimiting genera. Without deliberate weighting by arbitrary subdivision it only 

 produced two coded characters, one alternative and one ranked quantitative. 

 This may be an argument for the coding of all characters as dichotomies. Colour 

 characters were treated quantitatively rather than qualitatively since in these 

 termites colour is only a matter of progressive sclerotization and ranges from white 

 to black through yellow and brown. In an earlier work (Sands, 1965) an arbitrarily 

 decided scale of intensity employing 12 terms was used, and the same procedure 

 was followed here. It was a simple matter to give these numerical values on the 

 assumption that dark brown is more similar to brownish black than is pale brown. 

 In a situation where different pigments are found, a qualitative treatment would be 

 required but in the present case the quantitative approach seemed most appropriate. 

 Measurements of various body parts of both imago and worker castes were also 

 included in the list of characters. An attempt was made to avoid excessive weighting 

 of the general size factor by employing only those measurements that received large 

 positive or negative loadings in principal components and canonical variates analysis. 

 These are discussed in more detail in a later section. Multivariate methods of 

 handling large numbers of measurements or attributes of organisms have been 

 known for several decades and described in several textbooks (Kendall, 1957; 

 Harman, i960; Cooley & Lohnes, 1964; and Seal, 1964). 



Multivariate similarity analysis 



In recent years many taxonomic works have been published that make use of 

 these methods and they have come to be recognized as a regular part of the technical 

 armoury of the systematist. For this reason no list of references to individual 

 papers is given apart from the textbooks mentioned above. 



A total of 99 coded numerical characters was used for multivariate analysis by 

 means of the classification programme (CLASP) devised by J. C. Gower on the basis 

 of a method originally suggested by P. A. Sneath. It was carried out on the Orion 

 Computer at Rothamsted Experimental Station, Harpenden, Herts. The list of 

 characters is given below : 



QUALITATIVES: 



(i) Alternatives 



(1) Shape of posterior margin of imago head capsule 



(2) Shape of posterior margin of imago postclypeus 



(3) Pilosity of imago head capsule; presence or absence of a 'pelt' 



(4) Thickening of mesonotum between wing processes of imago present or 



absent 



(5) Thickening of metanotum between wing processes of imago present or 



absent 



(6) Median 'suture' of imago postclypeus present or absent 



(7) Frontal marks of imago head capsule depressed or flat 



