ETHIOPIAN NASUTITERMITINAE 17 



dealt with formally in that paper, although he clearly regarded all such related 

 species as belonging to the same genus. 



Imago. Left mandible with apical tooth as long as or slightly shorter than first marginal, 

 distance from apical to first marginals less to slightly more than half distance between first and 

 third marginals (left mandible index '37--54), second marginal obsolete or only represented by 

 slight undulation of cutting edge between first and third marginals ; right mandible with apical 

 and fust marginals subequal as kit, posterior cutting edges of first and second marginals 

 approximately equal ill length, molar plate with 9-1 1 regular transverse ridges, and no marked 

 irregularity of outline in surface view (Text-figs. 157-162). Postclypeus, length slightly less 

 than half width, to a quarter or less of width Fontanelle, usually pale coloured, slit-like, and 

 forked anteriorly, but in a number of species virtually obsolete, and scarcely different in colour 

 from rest of head capsule, sometimes visible only as an indistinct round or oval mark. 



Soldier. Monomorphic, though sometimes size differences appear to correspond to in 

 at which metamorphosis from worker caste took place. Nose a weak to strong cone, not 

 cylindrical in species of Ethiopian Region. Vestigial mandibles usually with points. Head 

 capsule without any pronounced constriction behind antennae. 



The characters given in the diagnosis are those which distinguish the genus from 

 others in the Ethiopian Region, and are not intended to be diagnostic on a world 

 scale, neither are the more generalized subfamily characteristics included. Only 

 Grallatotermes among the Ethiopian genera has a right molar plate which resembles 

 that of Nasutitermes, though certain Xcotropical and Oriental genera are similar. 

 Grallatotermes africanits Harris differs from Nasutitermes in having a long cutting 

 edge to the right second marginal, compared to the space between right apical and 

 first marginal, and a deep indentation of the cutting edge on the left mandible 

 between first and third marginals. The soldier also has a constricted head capsule. 



The genus is confined in the Ethiopian Region to rain forest, riverain gallery forest, 

 and forest outliers arising from locally moister conditions, or to moist woodland 

 approaching forest conditions and usually situated near forest. This has resulted 

 in a comparatively sharp division into two faunistic groups of species, one of which, 

 the larger, consisting of ten species, is confined to the forests of the Congo and 

 Guinean zones, including northern Uganda. The second consists of two species, 

 mainly found in the coastal forest and woodlands of East Africa, but extending 

 into Zululand in the South, and one of the two up the Rift Valley through Xyasaland 

 and the western border of Tanganyika to the borders of the Congo and Uganda at 

 Rwindi. The distribution of the species is shown on the maps (Maps 3-12). 



Keys to Species 



The increased understanding of the variability of all castes has led to difficulties in constructing 

 suitable keys to species. In the case of the imagos, it has been found necessary to resort to the 

 use of numerical indices to express differences in proportions where actual measurements overlap. 

 Some of the species are represented by very small numbers of specimens, and it is anticipated that 

 discovery of new material may necessitate the reassessment of the validity of key characters in 

 these cases. 



Imagos 



1 Postclypeus width 2-3 times length (Text-figs. 1-5, 8-17) ..... 2 

 - Postclypeus width more than 3 times length (Text-figs. 6, 18-23) • 7 



2 Eyes relatively larger in proportion to head-width, YY/E index under 26, ocelli 



closer to eyes, O-E distance 001-004111111. ....... 3 



