Vol. 32, pp. 135-138 June 27, 1919 



PROCEEDINGS 



OF THE 



BIOLOGICAL SOCIETY OF WASHINGTON 





THE STATUS OF THE SUBGENUS SIEBEROCITTA 



COUES. 



BY HARRY C. OBERHOLSER. 



The subgenus Sieberocitta is an interesting case. Originally 

 proposed by Dr. Elliott Coues 1 with Cyanocitta ultramarina var. 

 arizonae Ridgway as its monotypic type, it has been until very 

 lately rejected as based solely on color characters. Mr. H. S. 

 Swarth in a recent publication 2 has properly called attention 

 to the fact that this subgeneric distinction was originally made 

 on structural as well as color differences. On this basis Mr. 

 Swarth has revived Sieberocitta as a subgeneric group to include 

 Aphelocoma sieberii (Wagler) and its subspecies, leaving all the 

 subspecies of Aphelocoma calif omica in the typical subgenus. 

 Mr. Swarth did not examine the two Mexican species Aphelo- 

 coma unicolor (Du Bus) and Aphelocoma guerrerensis Nelson, 

 which, as it happens, are the key to the whole problem. An 

 investigation of these two species shows at once that color is 

 here of little or no value as a group distinction, and that we 

 must make our division, if at all, on structural characters alone. 

 The type of Sieberocitta differs from Aphelocoma calif omica, the 

 type of true Aphelocoma, in having the tail rounded and shorter 

 than the wing instead of graduated and longer than the wing. 

 So far as the other species of these two groups are concerned, 

 the shape of the tail is of little or no importance as a subgeneric 

 character, for it is at most but relative, and does not hold in all 

 the species under consideration. 



By the above criterion, Aphelocoma unicolor, which in pattern 

 of coloration is decidedly different from that of the species of 

 either group, is clearly referable to Sieberocitta. On the other 



iKey North Amer. Birds, ed. 5, I, 1903, p. 497. 



2Univ. Calif. Publ. Zool., XVII, No. 13, February 23, 1918, pp. 406-407. 



27— Pboc. Biol. Soc. Wash., Vol. 32, 1919. (135) 



