Sy stoma tics A:l 



NH-IATODE SYST^lATIC.^i 



According to Mayr et al. (1953)5 nematodes belong to the Kint^dom /.ni- 

 malia, Subkingdom Hetazoa, and Phyliirn Nematoda. Chitv70od and Chitwood 

 (1950) use "Nanatheln inthes" as the designation of the phylum. Ctoodey 

 (19$1) places the nematodes in the Subkingdom Vermes, Phylum Ascheliaintha, 

 and Class Nematoda, 



Vifhether the nematodes are considered a class or a phylum, there is fairly 

 general agreement on the classification of Chitwood (1933). According to 

 this scheme, all nematodes are divided into two large groups (classes or 

 subclasses) called Phasmidia and Aphasmidia. The classes are divided 

 into orders with names derived from the type genus of the order and end- 

 ing in -ida (e.p., Rhabditida) . Names of suborders end in -ina (Rhab- 

 ditina); of superfamilies in -oidea (Rhabditoidea) ; of families in -idae 

 (Rhabditidae); and of subfamilies in -inae (Rliabditinae) . The subfami- 

 lies are composed of genera and the genera of species. In addition, a 

 few subspecies have been named. 



As with plants and other animals, the various taxa are composed of forms 

 having a greater or lesser degree of resemblance and presumably have 

 evolved from cominon ancestry. Species in the same nematode genus may 

 differ from one another in only a few characters, and are usually easily 

 recognizable as belonging to the same genus. Genera in the same sub- 

 family differ to a larger degree, and so on through the higher categories. 



Nematode names are subject to the International Rales of Zoological 

 Nomenclature, and some knowledL';e of these rules should form part of the 

 basic information of the nematologist. At present, the best available 

 explanation of the rules is to be found in the book, "Methods and Princi- 

 ples of Systematic Zoology," by Mayr, Linsley, and Usinger. These rules 

 provide for the changing of nan-es under certain circumstances, and this 

 is often done with nematode names. Consequently, desired infoimation on 

 a given species of nematode may be found in literature files under several 

 different names. As examples, the root-knot nematodes have been transfer- 

 red from the genus Heterodera to the genus Meloidogyne ; many genera of the 

 Tylenchida were formerly grouped in the genus Tylenchus and later in the 

 genus Anf^uillulina ; and the genus Hemicycliophora was formerly known as 

 Procriconema . The table of contents of Goodey's "Soil and Freshwater 

 Nematodes" is the best guide to general classification of the soil and 

 plant parasitic forms available at present. However, it will be found 

 lacking in several respects since several important changes have been made 

 since the book was prepared about 19U9. 



It should also be remeinbered that, nematode taxonomy is in a fairly early 

 stage of development. New species are constantly being described and new 

 genera created, either through the discovery of new forms, the splitting 

 of old genera, or the correction of errors of the past. As concepts change. 



