1893.] 37 



OX A SPECIAL ACARID CHAMBER FORMED WITHIN THE BASAL 



ABDOMINAL SEGMENT OF BEES 



OF THE GENUS KOPTORTHOSOMA {XYLOCOPIN^). 



BY R. C. L. PERKINS, B.A. 



The genus Kopforthosoma was formed by Gribodo for the recep- 

 tion of certain species previously placed in Xylocopa. They differ 

 greatly from the bees of that genus in the structure of the posterior 

 part of the thorax, and the base of the abdomen. The scutellum is 

 abruptly deflexed posteriorly, so that a sharp edge is formed which ■ 

 slightly projects over the post-scutellum. The basal segment of the 

 abdomen is sharply truncate in front, the basal portion being strongly 

 concave, and is very closely applied to the thorax, the edge dividing 

 its dorsal and anterior surfaces, fitting beneath the sharp edge of the 

 scutellum. Owing to the concavity of the parts, a closed cavity is 

 thus formed between the hind part of the thorax and the base of the 

 abdomen. If the basal concavit}'^ of the first abdominal segment be 

 examined in the female bee, a distinct orifice will be found in the 

 middle, generally small and overhung with hairs, but in some species 

 large and quite exposed. An examination of the interior of this 

 segment will reveal a large chitiuous chamber, transverse, and filling a 

 large part of the interior of the segment in most species, but in some 

 smaller and rounded in form. The form of the chamber would appear 

 to be constant for a particular species of bee. 



The orifice above mentioned is the external opening of this 

 chamber. Examples of a species of Acarus of unusually large size 

 appear to be always found w'ithin the chamber ; sometimes they en- 

 tirely fill up the cavity. In dead examples of the bees an Acarus will 

 often be seen with its front parts projecting through the orifice, and 

 its existence was first made known to me in this manner. I have 

 examined the female of seven species of KopforfJiosoma, viz.. A'. Jntipes, 

 JL. tenuiscapa, K. cestuans, K. verticalis, K. ccerulea, K. caffra, and 

 K. trepida. 



In the females of all these species the chamber was found, and 

 Acari within in. It is noteworthy that the latter two species are from 

 South Africa, the others from India or the Indo-Malay region. The 

 males of the two first-named species have also been examined, as well 

 as a number of undetermined species, but they have no chamber for 

 Acari, although the external structure of thorax and abdomen is 

 similar to that of the female. The spot where the orifice of the 

 chamber is situated in the $ is in the other sex occupied by a more or 



