Revision of the genus nacobbus thorne and allen, 1944 (nematoda: tylenchoidea)

All four species and one subspecies of the genus Nacobbus Thorne and Allen, 1944 were studied and measured from type specimens. Nacobbus batatiformis Thorne and Schuster, 1956; N. serendipiticus Franklin, 1959; and N. serendipiticus bolivianus Lordello, Zamith and Boock, 1961 are proposed as synonyms of N. aberrans (Thorne, 1935) Tborne and Allen, 1944. Nacobbus aberrans is distinguished from the type species N. dorsalis Thcrne and Allen, 1944 by the larger number of body annules between the vulva and anus; the lower position of the vulva in the young female; and the shape and number of eggs retained in the mature female.