A NEW PROTOZOAN FROM THE LARVA OF THE BEETLE 

 OSMODERMA SCABRA 



By Clarke Courson Zeliff 

 Washingtonville, Pa. 



Smears from the hind intestine of the larva of Osmoderma scabra, a 

 large black beetle that inhabits decaying sawdust and wood, contain 

 abundant Nydotherus Leidy. An investigation of the literature 

 reveals that more than 25 species of this ciliate genus have been 

 described from about the same number of hosts. Description of the 

 new species is given below. 



The drawings herein were made with the camera lucida at X 1,600 

 and X 700. 



NYCTOTHERUS OSMODERMAE, new species 



Specific diagnosis. — Body of organism typically egg shaped. Size 

 50fjL to 87 fi long and 44^ to 68/1 wide. A large group are 66;u to 70m 

 long and 50^ to 60m w^ide. Nuclei oblong or convex and 24.6m long and 

 11.2m or 8m wide. The cytopharynx ends at 20.8m from the posterior 

 end and in the average-size specimen about 32m and 16m, respectively, 

 from the oral and aboral sides or surfaces. Cytopharynx 48m long. 

 Cilia 8m long and the rows 3.2m from each other. Micronucleus (pi. 1, 

 fig. 2) anterior to the macronucleus and frequently slightly imbed- 

 ded in it; the shape is oblong and the size 3.2m long by 2.4m wide. The 

 chromatin is distributed in small nearly spherical masses. A caryo- 

 phore, or suspensor of the nucleus, is visible in many specimens. 

 Cytoplasm in the anterior end differentiated from that posterior to 

 the nucleus by lack of vacuoles. A distinct cytopynge (pi. 1, fig. 2) 

 is located at the extreme posterior end. 



Dividing forms. — Stages of division of Nyctotherus have been ob- 

 served in detail by Zulueta (1916) in AT^. ovalis. The forms examined 

 by me (pi. 2) are much like those described and pictured by him, with 

 the exception of (pi. 2, fig. 2) an individual with two new cytopharyn- 

 ges formed previous to the division of the nucleus. As stated by 

 Zulueta, the organelles disappear before division, to be formed anew 

 in the daughter cells (pi. 2, fig. 1). It is not possible to follow the 

 activities of the micronucleus in the material available, but it has 

 been clearly seen in one organism (pi. 2, fig. 5) in the late phase of 



No. 2964. — Proceedings U. S. National Museum, Vol. 82. Art. 23 



172296—33 1 



