TRAVASSOSINEMA-THYROPYGI SP-N (NEMATODA, TRAVASSOSINEMATIDAE) FROM A SPIROBOLID MILLIPEDE FROM VIETNAM WITH SEM OBSERVATIONS ON HETH-IMIAS SPIRIDONOV, 1989 (NEMATODA, HETHIDAE)

A new species of the genus Travassosinema Rao, 1958 is described and i llustrated from the intestine of the spirobolid millipede Thyropygus a llevatus (Karsch, 1881) collected in Vietnam. T. thyropygi sp. n. is c haracterized by the relatively long body (2.4-3.2 mm) with the tail oc cupying about 46 % of the body length and by the absence of lateral al ae. It most closely resembles the type of the genus, T. travassosi Rao , 1958, but has a longer body and markedly smaller eggs. A key to the species is provided. SEM studies of the elaborate cervical armature of Heth imias Spiridonov, 1989, an unusual gut parasite from a Rhinocric us sp. from Cuba, are presented and the description of the female cerv ical region emended. The various forms and arrangements of the female cervical spination and their significance in the taxonomy of the genus are discussed. Although spination of the cervical collar can be used to divide the genus into two broad groups : Group 1 with numerous smal l spines with fused bases and Group 2 with fewer, larger, spines with separate bases; the former group can itself be subdivided on the basis of presence or absence of serrate lappers and on the presence or abse nce of spiny combs and spiny studs/button-like formations. Current kno wledge of the variability in the genus is, however, too incomplete to allow definite conclusions as to the supraspecific value of these char acters.