Free-living nematodes from nature reserves in Costa Rica. 4. Cephalobina

Four species of Cephalobina: Geraldius bakeri, Diastolaimus croca, Trualaimus culeatus and Tricirronema tentaculatum are described and illustrated on the basis of material collected in Costa Rica. A scanning electron microscope (SEM) study of G. bakeri is given for the first time. Diastolaimus croca is found to have a circle of six setiform processes anterior to the true labial setae. Detailed descriptions of the female reproductive system in G. backeri, D. croca and Macrolaimus sp. are given. The use of the female reproductive system and structure of the labial sensilla in the systematics of the family Chambersiellidae, together with its taxonomic placement, are discussed. Notes on the systematic position of the family Bicirronematidae and a key to the species of this family are given.