W. A. SANDS 



T riner vitermes saudiensis sp. n. 



(Text-figs. 301, 302, 320, 321 ; Map 3.) 



Imago. Colouration uncertain due to fading in old dried specimens, but thought to be similar 

 to T. rapulum. 



Posterior margin of head capsule behind eyes less than semi-circular, slightly sinuate immed- 

 iately behind eyes ; fontanelle distinct, Y-shaped, lateral arms long, reaching almost half-way 

 to ocelli, slender but slightly dilated at point where termination occurs in other species ; frons 

 with two diverging depressions in front of fontanelle, or these united ; eyes very short oval, 

 moderately prominent in proportion to own diameter, small relative to head width, YV/E index 

 3'5~3'9 ! ocelli medium sized, separated from eyes by more than half to more than three- 

 quarters own least diameter ; postclypeus moderately to strongly inflated, width 2-1-2-4 

 times length, anterior margin slightly concave, posterior margin convex, rounded, slightly arched 

 in middle ; molar plate of right mandible with 7-8 ridges ; antennae 15 segmented, If, IV, and 

 V subequal, III and VI subequal and slightly longer than these. 



Pale coloured " scent " gland on anterior margin of fifth $ abdominal sternite small ; cerci 

 of $ as long as width across base, slightly mamilliform conical. 



Pilosity of vertex of varying length, not forming a " pelt " or " mat ". 



Measurements (10 specimens from 1 locality) in millimetres. 



Head width across eyes 

 Greatest diameter of eye 

 Ocellus 

 Ocellus to eye 

 Width of pronotum 

 Length of pronotum 

 Length of hind tibia 

 Length of fore wing 

 Soldiers. Unknown. 



T. saudiensis is separable, from T. dispar and T. rapulum by the proportionately 

 smaller eyes, with the ocelli more distant from them, and the shorter $ cerci. The 

 same characters apart from the cerci distinguish it from T. togoensis and T. occident- 

 alis. The wide spreading lateral arms of the fontanelle are unlike any other 

 Trinervitermes except some T. trinervoides. 



T. saudiensis is described here because it is so distinct from the other species of the 

 Ethiopian Zoogeographical Region and because the existence of a further Trinervi- 

 termes species in the Arabian Peninsula is an important link in the distribution of 

 the genus in Africa and India. I consider it most improbable that this species is 

 the imago of T. arabiae. The various primitive features such as the wide branched 

 fontanelle, small eyes widely separated from ocelli, the long postclypeus, slightly 

 mamilliform cerci and small ventral scent gland, are shared with several other species, 

 but none shows such a combination of features common to the rest, suggesting that 

 this species may be close to the ancestral form of the genus. There is a possibility 

 that this is the at present unknown imago caste of Mycterotermes meringocephalus , 

 which might be expected to show a similar combination of features. 

 Two vials of this species were studied. 



Holotypecy, Saudi Arabia : Jidda, 24.xi.1926 {H. St. J. B. Philby), B.M.(N.H.). 

 Allotype $, same data as holotype, B.M.(N.H.). 

 Paratypes <$, same data as above and also 3.11.1934 (G. L. Bates), B.M.(N.H.). 



Range 



Mean 



5 1-61-1-76 



i-66 



/e 0-43-0-48 



046 



0-16-0-18 x 0-20-0-25 



017 x 



010-013 



Oil 



1-38-1-61 



1-48 



0-84-0-94 



090 



2-04-2-24 



217 



15-50-16-30 



1573 



