MICROSPORIDIA — PARASITIC IN MOSQUITOES 167 



THELOHANIA ILLINOISENSIS NOV. SPEC, PARASITIC IN 

 ANOPHELES PUNCTIPENNIS 



Thirty-four larvae of Anopheles punctipennis were collected 

 from the drainage ditch at Urbana, Illinois, on September 25 

 and October 3, 1919. They were kept in two aquaria in the lab- 

 oratory. Six from the first collection were allowed to complete 

 their metamorphosis. Among the remaining twenty-eight, one 

 individual was more opaque in color and less active in motion 

 than others, and proved, on microscopical examination, to be 

 infected by a Microsporidian, to which the name Thelohania illi- 

 noisensis is given. The remaining larvae were subjected to care- 

 ful examination. Only one of these was found infected. Unfor- 

 tunately, the number of parasitized larvae was small and none 

 of the sectioned larvae was infected. The two infected larvae 

 were studied in fresh as well as in fixed and stained smears. 



The adipose tissue seems to be the only seat of infection. 

 Whether or not other tissues are affected could not be determined, 

 because the sectioned larvae contained no parasites. The 

 smears showed mainly isolated spores and sporonts with young 

 spores. The generic position of the parasite in the genus Thelo- 

 hania is, however, without doubt, because of the abundant pres- 

 ence of octosporous sporonts. The schizogony as well as spo- 

 rogony could not be studied, as young stages were very few in 

 number. 



The sporont with eight spores was usually rounded (fig. 61) or 

 rarely oblong (fig. 69). The spores were dispersed without any 

 order inside of the sporont membrane and were imbedded in 

 faintly staining protoplasm. The rounded sporonts with mature 

 eight spores measure 13 n in average diameter, while oblong 

 forms measure 16)U by 8^. 



The spore is oval in form with equally rounded extremities. 

 It is less refractive than that of Nosema bombycis or Nosema 

 apis. It is uniform in size, no dimorphism of spores being found. 



In fresh state, the spore membrane is clearly seen separated 

 from its contents (figs. 62, 63). The contents of the spore are 

 very peculiar in shape; one end narrow and truncate, the other 

 regularly rounded along the inner surface of the membrane. 



