NEW FORMICID/E FROM BARRO COLORADO ISLAND. l6l 



group is regarded by Mann as a distinct subgenus, for which he 

 has proposed the name Wheelerimyrmex. I find that there is 

 also a difference in the number of palpal joints in these two 

 groups. In Megalomyrmex sens. str. (M. bittiberculatus Fabr.) 

 the maxillary palpi are 4-jointed, the labial palpi 3-jointed. 1 In 

 Wheelerimyrmex I find the maxillary palpi to be 3-jointed, the 

 labial palpi 2-jointed. The guest ant, which really represents a 

 new subgenus and species and is described in the sequel as 

 Cepobroticus symmetochus, has the same number of palpal joints as 

 Wheelerimyrmex, but the mandibles are intermediate between the 

 two other subgenera, having a sharp angle between the basal and 

 apical border, and the latter with a large terminal and five or six 

 small basal teeth. The antennae, moreover, are short, all the 

 funicular joints, except the last being decidedly broader than long 

 and the clava absent. The promesonotal suture is obsolete but 

 this character occurs also in one species of Wheelerimyrmex 

 (silvestrii). In sjostedti the suture is as distinct as it is in the 

 species of Megalomyrmex sens. str. The eyes of the worker 

 Cepobroticus are rather small. 



It is, perhaps, significant that Emery (1921) has placed the 

 genus Megalomyrmex in his tribe Monomorii, in the midst of a 

 series of Old World genera Hagioxenus, Wheeleriella, Phacota, 

 Xenomyrmex and Liomyrmex which are known to have xeno- 

 biotic or parasitic habits. Unfortunately very little is known 

 concerning the habits of the described species of Megalomyrmex. 

 The only data I have been able to secure are a few notes by Mann 

 on M. tuberculatus and M. (W.) silvestrii. Of the former he says 

 (1916, p. 445): "This form, which is confined to the upper 

 Amazonian region, attends Membracidse and the workers were 

 generally found in company with these on shrubs in the dense 

 forest. The nest is subterranean, the entrance nearly always at 

 the base of a tree. The living insect is slow in its movements." 

 Concerning silvestrii, which he observed in Honduras, he says: 

 "A good series of workers were taken at Ceiba and San Juan 

 Pueblo, nesting in the ground and in rotten logs. It is a timid 

 species and very active when disturbed." These notes indicate 

 that the species of Megalomyrmex sens. str. and the subgenus 



1 Forel and Emery give 3 joints for each palpus. 



