35 Formicidae from Easter Island and Juan Fernandez. 



By 

 WILLIAM MORTON WHEELER. 



The ants taken by Mr. K. Backstrom, zoologist to Professor Skottsberg's 

 expedition to Easter Island and Juan Fernandez comprise only seven small 

 forms, all belonging to well known »tramp», or vagabond species of Old World 

 origin, with the single exception of Ponera trigona var. opacior, which is widely 

 distributed in tropical and subtropical America. It is therefore interesting to 

 note that the affinities of the ant fauna of these islands, so far as they are 

 revealed by the collection, are very largely with Polynesia. This is clearly 

 indicated by such species as Prenolepis bourbonica and obscura, Plagiolepis 

 mactavishi and Cardiocondyla nuda which have not been taken in America. I 

 have noted in the following paragraphs the known range of each of the seven 

 forms taken by the expedition. 



1. Ponera trigona Mayr. var. opacior Forel. $?<;?• — »Under stones. » 

 The types of the species are from Sta. Catharina, Brazil, and of those the var. 

 opacior from St. Vincent, West Indies. I have seen specimens of the latter 

 from Concepcion, Chili (R. Thaxter), Texas, California, Florida, Mexico and 

 numerous stations in the West Indies. It seems to be very common in the 

 Argentine. FoREL has described a subsp. convexiuscula from Queensland, 

 Australia. — Easter Island. 



2. Cardiocondyla nuda Mayr. subsp. minutior Forel. 

 Worker. Length i,6 — 1,8 mm. 



Differing from the typical nuda in its smaller size, in having the head 

 more rectangular, with more pronounced posterior corners, and the thorax,' 

 petiole and postpetiole decidedly opaque and more coarsely sculptured. The 

 antennal scapes are distinctly shorter and the postpetiole is very noticeably 

 smaller, more depressed dorsally, as compared with the petiole, though twice 

 as broad as the latter and distinctly broader than long. Epinotal spines more 

 acute. Color and pubescence much as in the typical nuda and the subsp. mauri- 

 tanica Forel. 



Female (undescribed). Length 2 — 2,3 mm. 



Differing from the female of the typical form in the same characters as 

 the worker; the dorsal flattening of the postpetiole even more pronounced. 

 Wings like those of the typical form, hyaline and iridescent, with colorless veins. 



