188 ILLINOIS BIOLOGICAL MONOGRAPHS [398 



Satellite : 



Length protomerite 13 17 18 10 



Length deutomerite - -... 57 50 50 37 



Width protomerite 28 20 28 16 



Width deutomerite 32 30 50 18 



Total length sporont 70 67 68 47 



Ratio 



length protom. : total length 1:5.4 1:4 1:3.8 1:4.7 



width protom. : width deutomerite 1 :1.2 1 :1.5 1 :1.8 1 :1.1 



Diameter nucleus 10 8 9 



Shape and size differentiate this species from all the other species 

 found in the Tenebrionidae. For list of these gregarines, see Index of 

 this chapter on Coleopteran parasites. 



GREGARINA GRACILIS Watson 



[Figure 170] 



1915 Gregarina gracilis Watson 1915 :32 



Host : Larva of an unidentified member of the family Elateridae. 

 Location : Urbana, Illinois, October, 1914. 



The parasites infect the intestine of the host. 



The sporonts are biassociative. The satellite is generally the larger, 

 contrary to the general rule that either the primite is slightly the larger or 

 the two sporonts differ but little in size. The body is elongate cylindrical, 

 rather longer in proportion than is true of most members of the genus. 

 The protomerite of the primite is hemispherical with no papilla or inden- 

 tation at the anterior end. The constriction at the septum is shallow ; the 

 protomerite is one and one third times as broad as high and averages one 

 sixth the total length of the sporont. The protomerite of the satellite is 

 of practically the same width as that of the primite, but is slightly flat- 

 tened. The deutomerite is elongate cylindrical, a little wider in the mid- 

 dle portion and tapering slightly, ending in a broadly rounded extrem- 

 ity. The interlocking device is not well constructed, sporonts of an asso- 

 ciation being barely contiguous and easily dissociated by slight pressure. 



The body is pearl gray, and the protoplasm is not homogeneous but 

 consists of large and small granules sparsely scattered throughout. The 

 anterior end of the protomerite is devoid of granules. The nucleus is not 

 visible in adults not because of the density of the protoplasm but because 

 of the fact that the large granules seem to cling to or lie in the region of 

 the nucleus in a cluster. The region occupied by the nucleus can, there- 

 fore, be easily detected although its outline is obscured. The nucleus is 



