THE SOLDIERLESS TERMITES OF AFRICA 149 



surface, posterior margin of each scale fringed with minute spicules. Membranous wall of valve 

 beyond cushions with very numerous fine small spicules arranged in 15-20 rows, broken up 

 into fringed lobes, between cushions. Other characters in generic diagnosis. 



Measurements (one specimen) in millimetres. 



Head width (W) 080 



Fore tibia width (T w ) • • . 014 



Fore tibia length (Ti) .... 059 



Postclypeus length (Pel) . . . 026 



Left mandible, apical to first marginal (La) o-ii 



Left mandible, first to third marginal (Li) . on 

 Left mandible, third marginal to molar 



(L m ) 004 



Right mandible, apical to first marginal 



(Ra) 011 



Right mandible, first to second marginal 



(Ri) 009 



Right mandible, second marginal to molar 



(Rm) 005 



A . imbellis has already been compared wi th A . chirotus and A . epins under those 

 species. It is distinguished from A. tithasus in both imago and worker castes by 

 its much more strongly inflated postclypeus, and in the imago by the ocelli being 

 much closer to the eyes. In the worker caste, A. tithasus also has noticeably bristly 

 fore coxae in contrast to A . imbellis. The abdomen of the worker caste appears to be 

 dehiscent in this species. 



Holotype queen, paratype king, and workers from type-colony, Democratic 

 Republic of Congo: Katanga, Keyberg, near Elizabethville, 21. v. 1948 

 {A. E. Emerson), in American Museum of Natural History. 



The single known nest-series was found near the surface of an old mound, probably 

 of Cubitermes sp., in grassy woods near the top of a rocky hillside. 



Acholotermes tithasus sp. n. 



(Text-figs 346, 347, 354, 355 & 374-379; PI- 3. figs 5 & 6) 



Imago. Head capsule sepia-brown, darker above ocelli; fontanelle small, circular, flat, 

 less than one-fifth size of ocellus, pale brown; medial spot twice as large as fontanelle, flat, 

 coloured as head; postclypeus sepia-brown, labrum yellow-brown; frontal marks flat crescents, 

 coloured as head; antennae brown. Pronotum sepia-brown, meso- and metanota brown, 

 transverse dark sutures absent from mesonotum, weakly present on metanotum; femora and 

 tibiae pale yellow-brown, tarsi yellow. Abdominal tergites brown, dorsal stigmata paler, 

 sternites yellow-brown laterally with paler ventral stigmata, yellow in middle; cerci yellow. 



Posterior margin of head capsule slightly arched, not evenly rounded; ocelli rather small, 

 separated from compound eyes by slightly more than own least diameter; postclypeus weakly 

 inflated, Pcl/W, 0-23, posterior margin almost obtusely angular, not evenly rounded, median 

 suture weak. Apical teeth of mandibles very long, La/Li, 0-91-1-04, Ra/Ri, 1-33-1-45; sub- 

 sidiary marginal tooth of left mandible level with edge of molar prominence in surface view, 

 complex ratio La/Li. L m , 13-50-16-29; point of first marginal tooth of right mandible slightly 

 behind line of apical to second marginal, anterior edges of first and second marginals equal. 



