wheeler: ants of the genus formica. 409 



9. F. sanguinea subnuda Emery. 



F. sanguinea rubicunda var. subnuda Emery, Zool. jalirb., Syst., 1895, 8, p. 



335, y . 

 F. sanguinea subsp. subnuda Wheeler, Ants, 1910, p. 458, 570. 



Worker. Length 5-8 mm. 



Head like that of the typical rubicunda but the clypeal emargina- 

 tion is much shallower, often reduced to a feeble sinuosity. Epino- 

 tum often more rounded and less angular in profile, especially in 

 smaller workers, in larger ones, however, often as angular as in the 

 typical rubicunda and aserva. Petiole rather broad, with sharp, entire, 

 or very feebly sinuate superior border. 



Surface like that of rubicunda, the gaster usually slightly more 

 opaque. 



Hairs grayish or yellowish, much less abundant than in the typical 

 rubicunda and its var. sublucida, nearly always completely absent on 

 the thoracic dorsum, gula, and petiolar border. There are only a 

 few hairs on the upper surface of the head and those on the gaster are 

 decidedly short and sparse. Pubescence on gaster dense but finer 

 than on the typical rubicunda, concealing the surface; on the thorax 

 and head very sparse or absent and often not perceptible under an 

 ordinary magnification. 



Color variable, but usually a light, rich red like that of the typical 

 rubicunda, in some cases, however, more brownish; gaster black, as a 

 rule, but occasionally with each segment brownish or reddish towards 

 its base. 



Female. Length 8-9 mm. 



Closely resembling the worker in sculpture and pilosity, but the 

 red portions of the body somewhat browner. Dark spots on the 

 mesonotum faint or wanting. Wings colored as in the tj^^ical rubi- 

 cujida, if anything somewhat more deeply. Clypeal border more 

 deeply notched than in the worker. 



Male. Length 8-9 mm. 



Differing from the males of the preceding forms of sanguinea in 

 having the anterior border of the clypeus entire and evenly rounded; 

 its surface is convex and carinate. Mandibles dentate. Petiole 

 somewhat more compressed anteroposteriorly and with a sharper 

 border than in rubicunda. There are no erect hairs on the head and 

 thorax and the hairs on the gaster are short and sparse. Pubescence 

 short and dilute so that the surface of the head, thorax, and gaster is 

 more shining than in the typical rubicunda. 



Hosts (Slaves). F. fusca vars. subsericea, argentea, subaenescens, 

 and gelida; large colonies often without slaves. 



Type locality. — British Columbia : Yale, (Dieck). 



British Columbia: Vancouver I.; Field, Carbonate, 2,800ft., Lake 



