Bursaphelenchus suri n. sp.: A second Bursaphelenchus syconial parasite of figs supports adaptive radiation among section Sycomorus figs

Abstract

The nematode genusBursaphelenchusis a highly divergent group. This genus mainly consists of mycophagous entomophilic species, but some species have specialized as obligate or facultative plant parasites, facultative insect parasites, or exhibit feeding dimorphism (phenotypic plasticity) leading to mycophagous and predatory forms. In the present study, a newBursaphelenchusspecies,B.surin. sp. was isolated from fresh syconia (figs) ofFicus surand is described and illustrated based on its typological characters and molecular phylogenetic status. The new species is characterized by its highly derived feeding structures found in obligate plant parasites, lip possessing a labial disc and a long and thick stylet with a long conus and extremely well-developed basal swellings. In addition, slender body of both sexes is characteristic of the species. The new species is phylogenetically and typologically closely related toB.sycophilus, i.e., these two species share the characteristic feeding structures and form a well-supported clade within theB.fungivorusgroup in the genus. Biologically, these two species are both isolated from fresh figs of the sectionSycomorus. However, the new species differs fromB.sycophilusby the length of the female post-uterine sac and the shape of the male spicule, i.e., the new species has a long post-uterine sac and spicule condylus without dorsal recurvature. Thus, the new species is the second obligate fig parasite of the genus, and the evolutionary relationship between theB.surin. sp. andB.sycophilusclade and sectionSycomorusfigs is hypothesized as an example of adaptive radiation with more species to be discovered.