724 Annals of the South African Museum. 



epinotum in this sub-genus resembles that of Myrmoturba, but the 

 dorsum is wide and never ridge-like or cristate, the sides being more 

 oblique. The declivity is usually clearly delimited from the dorsum, 

 which is rarely the case in Myrmoturba. In both the 21. and 3, the 

 pubescence is very characteristic, being long, generally decumbent 

 and silky, and often golden or silvery. The head is nearly always 

 triangular (including the closed mandibles), the sides usually convex. 

 All our species are arboricolous, nesting in hollow trunks and stems. 

 As most of the species are unknown to me in nature, I have been 

 limited to citing the original descriptions, which are unfortunately 

 not so much detailed diagnoses as lists of differences between one 

 form and another. 



The sub-genus has recently been reviewed by Dr. Santschi (Ann. 

 Soc. Ent. France, vol. 84, pp. 266-278, 1915), and the following key 

 to the species is largely based on the one which is presented in that 

 paper. 



Key to the species of Myrmotrema, 21. 



(4) 1. Head and thorax brownish red ; dorsum of the epinotum, at least in the 



2J., broad, fairly horizontal lengthwise. 

 (3) 2. Abdomen black and very shining 



Robecchi, Emery, race rhodesiana, Forel. 

 (2) 3. Abdomen brownish red, fairly dull 



Robecchi, Emery, race troglodytes, Forel. 



(1) 4. Head aiid thorax (and abdomen) black; dorsum of epinotum narrower, 



oblique. 



(10) 5. Pit-like punctures on the head confluent, much larger than the intervals 



between them ; the pubescence arising from them long, as abundant and 



as long as the pubescence on the abdomen. 



(9) 6. The pubescence on the cheeks not quite decumbent but oblique, as long or 



nearly as long as the apical width of the scape. 

 (8) 7. Tibiae brownish black. Dorsum of epinotum slightly convex 



auropubens, Forel. 

 (7) 8. Tibiae reddish. Dorsum of epinotum straight. Mesonotum of the Q dull 



auropubens, var. Absalon, Santschi. 

 (6) 9. Pubescence shorter and decumbent auropubens, var. Jacob, Santschi. 



(5) 10. Pit-like punctures on the head smaller than the intervals between 



them, not deep, the pubescence arising from them very short or even 



absent. 

 (16) 11. Abdomen dull, densely punctured. Pubescence generally fairly long. 

 (15) 12. A glabrous median longitudinal line on the abdomen of the 2|_, sometimes 



indistinct in the ^. 

 (14) 13. 2J. j The scape extends beyond the hind margin by not more than the length 



of the 1st joint of the flagellum ; pubescence brassy-golden, greyish on the 



head in the ^ minor .... postoculatus, Forel. 



