A NEW GENUS OF DISTOMES (TREMATODA) WITH 

 LYMPHATIC VESSELS* 



v>* . 



(With One Plate) 



suj| i-i ^ t^ A 



H. W. Manter \ti\ -^^-^ 



University of Nebraska 



The trematodes described in this paper are but two of over 100 

 species collected from marine fishes in 1934, during the third G. 

 Allan Hancock Expedition to the Galapagos Islands. The author's 

 presence on this expedition was sponsored in part by the Carnegie 

 Institution of Washington. A brief preliminary report on the trema- 

 todes collected has been made (Manter, 1934) and a more complete 

 report on the digenetic forms is in preparation. An early description 

 of these two forms is felt justified in view of their significance in 

 connection with the phylogeny of the Distomata. The author has 

 already indicated (Manter, 1935) a relationship between certain 

 allocreadiid-like distomes (Megasolena Linton and Hapladena Lin- 

 ton) and amphistomes. The new genus described below further sub- 

 stantiates such a view and indicates that the Anallocreadiinae in 

 particular may be involved. A discussion of these relationships will 

 follow a description of the new species. 



Apocreadsum mexicanum, new genus, new species 

 (Plate 2, figs. 1-3) 



Host: Labrisomiis xanti Gill 



Position: Intestine 



Locality: Tangola Tangola, Mexico 



Incidence: 18 specimens from a single host 



The body is elongate, tapering slightly and bluntly rounded at 

 the anterior end, pointed at the posterior end, much flattened, espe- 

 cially posterior to midbody where the edges of the body become very 

 thin and thrown into frill-like folds. The cuticula is scaled as far 

 back as midbody. Mature specimens measure from 2.151 to 4.110 

 mm. in length by 0.757 to 1.096 mm. in greatest width. The body 



* Studies from the Zoological Laboratories, the University of Nebraska, No. 191. 



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