ETHIOPIAN NASUTITERMITINAE 71 



Central African Republic : Haut Mbomu, Zemio, iii.1948 (N. A. Weber), 

 A.M.N.H. 



Congo : Niangara, 20.V.1913 (H. Lang, J. P. Chapin) ; Dika,* 26.iii.1925 (H. 

 Schonteden) , A.M.N.H. ; Tora, 26. ix. 1926, 2 vials (H. Burgeon) ; Garamba Nat. 

 Park, 6.vii.i95i (Miss. deSeager), Inst, des Pares Nat. du Congo, Brussels. 



Sudan : Delami, 20. v. 1927 (W. Ruttledge). 



A total of 86 nest series were examined and material is in the British Museum 

 (Natural History) except where otherwise stated. 



F. tenebricus is a species occurring in the Guinean savannah vegetation zones from 

 the forest edge to the relatively dry Sudan type (Keay et al., 1959, vegetation types 

 8, 16, 17, and 20). In this respect its distribution north of the Congo forest is as 

 wide as the combined distributions of its two congeners F. coatoni and F. contractus 

 in similar vegetation zones to the south of the forest block. It sometimes constructs 

 a small hard earth mound with dark carton interior but is more commonly found 

 inhabiting parts of mounds constructed by other genera such as Cubitermes, Trinervi- 

 termes and Macrotermes. It is also found under stones, in dead branches on trees, 

 and in narrow earth runways which it constructs in foraging. 



RHADINOTERMES gen. n. 



(Rhadinos, Gr., " tapering ") 



Type-species, Eutermes coarctatus Sjostedt, 1902a : 304. 



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

 from apical to first marginal about one-third distance between first and third marginals (left 

 mandible index -32--36), second marginal obsolete, cutting edge between first and third mar- 

 ginals entire ; right mandible with apical and first marginals subequal as left, first marginal 

 with small subsidiary " tooth " near basal junction with apical, and with posterior cutting edge 

 exposed beyond anterior edge of second marginal longer than posterior cutting edge of latter ; 

 right molar plate in surface view with weak indentation near basal end of anterior margin, 

 posterior margin extending in rounded flange, first molar ridge forming a stout tooth, 6-7 

 remaining ridges diminishing towards base (Text-figs. 182, 183). Fontanelle, very narrow slit- 

 like, scarcely bifurcate anteriorly in $, more clearly in 9. slightly to distinctly paler than head. 



Soldier. Monomorphic. Nose conical. Vestigial mandibles with small points. Head 

 capsule sharply constricted behind antennae, posterior lobe commonly only about one-fourth 

 wider than anterior. Antennae 12 segmented. 



This genus is proposed to accommodate the single African mainland species 

 coarctatus Sjostedt, hitherto included, because of similarities in the soldier castes, in 

 the Malagasy genus Coarctotermes of which the type-species is Eutermes clepsydra 

 Sjostedt, 1904 : 108. The imago differs from Rhadinotermes coarctatus in a number 

 of features. The left mandible index is -30, and the third marginal tooth in fresh 



*A note on the locality Dika, recorded by Emerson (1928) as 7° 50' N., 18° 45' E., i.e. near Ft. Crampel, 

 C. Afr. Rep. 



Other localities of this name exist at 4 25' N., 21 ° 41' E. ; 5 59' N., 15° 13' E. ; 5 33' N., 20 00' E., 

 in C. Afr. Rep., at 4 36' N., 28 36' E. in Sudan, and in Congo at 4° 17' N., 27 42' E., and 4° 09' N., 

 27° 40' E., one of these last probably being that known to H. Schouteden. 



