Studies On the Genus Criconemoides Taylor, 1936 With Descriptions of Eleven New Species and Bakernema Variabile N. Sp. (Criconematidae: Nematoda)

Abstract

The nominal species of Criconemoides now total 85, eleven of which are described here as new. Additional information and illustrations are given for seven described species. Redescriptions are made for crotaloides, mutabilis, macrodorus and sphaerocephalus based on type specimens of the original authors found in the USDA Nematode Collection at Beltsville, Maryland. Designations of lectotypes and paralectotypes were made for these four species. Males of macrodorum and mutabilis are described for the first time. A new species of Bakernema also is described. Representatives of the genus Criconemoides are found world-wide virtually in every area where nematological research has been initiated. Not many species are known to be widely distributed but at least five species are on two or more continents and C. sphaerocephalus has been reported from Europe, North and South America, Hawaii, Africa and India. It is expected that many more species will be equally or more widespread because collections are only in the initial stages or have not even begun in many parts of the world. The morphological characters which are especially important in the taxonomy of Criconemoides include the type and number of body annules, the absence or presence and nature of sublateral lobes on the lip region, annulation of the lip region (especially the first two annules), stylet length and proportion of parts, location of vulva and anus, and tail shape. No longitudinal lines or incisures denote the lateral field but in a few species frequent anastomosis creates the semblance of a line in that area. Occasionally regular arch-like structures in the annules occur in the lateral field area. Cuticular configurations of two general types are reported for 17 species. The females of some species have rough or irregular posterior edges on the annules. Others have many fine indentations creating a minutely scalloped or serrated appearance. Some larvae also have pronounced development of cuticular protuberances as scales or spines quite distinct from the smooth cuticle of their adult stage. Other species have larvae with configurations similar to the adults. These cuticular characters should one day prove valuable in establishing relationships. Cuticular variations in larvae and adults complicate the distinction of Criconema, Bakernema and Criconemoides which are characterized principally on this character. Additional information is needed to provide a more sound basis for indicating relationships in this variable group of nematodes.