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

PLoS One. 2022 Apr 6;17(4):e0265339. doi: 10.1371/journal.pone.0265339. eCollection 2022.

Abstract

The nematode genus Bursaphelenchus is 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 new Bursaphelenchus species, B. suri n. sp. was isolated from fresh syconia (figs) of Ficus sur and 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 to B. sycophilus, i.e., these two species share the characteristic feeding structures and form a well-supported clade within the B. fungivorus group in the genus. Biologically, these two species are both isolated from fresh figs of the section Sycomorus. However, the new species differs from B. sycophilus by 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 the B. suri n. sp. and B. sycophilus clade and section Sycomorus figs is hypothesized as an example of adaptive radiation with more species to be discovered.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Biological Evolution
  • Female
  • Ficus* / parasitology
  • Male
  • Parasites*
  • Phylogeny
  • Rhabditida*

Grants and funding

This work was supported in part by the National Research Foundation of South Africa for financial support (grant 77256 to J.M.G.) and Grant-in-Aid for Scientific Research (B) from the Japan Society for the Promotion of Science (20H03026 to N.K.). The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript. Therefore, any opinion, findings and conclusions or recommendations expressed in this material are those of the authors and therefore funders do not accept any liability in regard thereto.