Ultrastructural and molecular identification of a Wolbachia endosymbiont in a spider, Nephila clavata

Wolbachia-like bacteria were observed in the egg cells of golden orb-weavin g spider, Nephila clavata, by means of transmission electron microscopy. Th e bacteria exhibited the typical morphology of Wolbachia, including three e nveloping membranes. Based on the amplification and sequencing of partial 1 6S rDNA and ftsZ gene, the bacteria were identified as Wolbachia, intracell ular, transovarially inherited alpha-proteobacteria in invertebrates. Phylo genetic analysis based on 16S rDNA and ftsZ gene sequences invariably indic ated that the intracellular bacteria from N. clavata belonged to group A Wo lbachia, which were found only from insects. Clustering of Wolbachia from N . clavata with group A Wolbachia indicates that the bacteria were probably transferred horizontally between insects and the spider.