Paras. B:2 



M. i ncognita a crita Chitwood, 19l49 



M. arenaria (Neal, I889) Chitwood, I9I49 



M. arenaria thamesi Chitwood, 19^2 



M. inornata Lordello, 19^6 



M. brevicanda Loos, 1953 



M. acronea Coetzee, 1956 



At the present time, the following species and subspecies are known to 

 occur in the United States: Mel o idogyne incognita , M. incognita acrita , 

 M. hapla , M. arenaria , M. arenaria thamesi , and M. javanica » Detailed 

 descriptions of these forms are given by Chitwood (19U9) . Sasser (195iU) 

 studied the host-parasite relationships of certain of the root-lcnot 

 nematode species and proposed a method of identification by host reac- 

 tion. Taylor, Dropkin, and Martin (1955) discuss in detail the identi- 

 fication of the various known species. This paper is very useful 

 because of its illustrations and a key to the species reported up to 

 1955 (which includes the knoxm species in the United States up to the 

 present) . 



The reader is referred to a recent review of the genus Meloidogyne by 

 Franklin (1957) which deals with some aspects of the taxononry of these 

 nematodes. The taxonomy of these forms is not easy and it involves an 

 appreciation of the fact that one is not dealing with identical speci- 

 mens, but rather with specimens which fall within relatively consistent 

 morphological and host ranges . Separation of the species is of prac- 

 tical importance because the host ranges of the different species .are 

 not identical and thus offer a means of control. 



It is of Interest to note that a new genus, Meloidodera , has been re- 

 ported (Cidtwood et al, 1956). As its name suggests, it has features 

 of both Meloidogyne and Heterodera . It is intermediate between them 

 in that, unlike root-knot nematodes, no gall is formed in the plant, 

 the female body wall is tough, and there is retention of eggs within 

 the body. It differs from the cyst-forming nematodes in that no dis- 

 tinct cyst stage exists and there is a distinct pattern form of the 

 anniiles. There are other defijiite morphological distinctions which 

 clearly set the Meloidodera apart. The original description should 

 be studied, because this nem-atode is already being found in various 

 places in the United States. 



