Bursaphelenchus penai n. sp. (Tylenchomorpha: Aphelenchoididae), a phoretic associate of ambrosia beetles (Coleoptera: Scolytinae) from avocado in Florida

During an experimental host-plant survey for the invasive redbay ambrosia beetle,Xyleborus glabratus, in Homestead, Florida, it and three native species of ambrosia beetle,Xyleborus affinis,X. volvulusandXyleborinus graciliswere found to be associated with aBursaphelenchusspecies. This nematode species, isolated from ambrosia beetles from the tribe Xyleborini, was cultured onMonilinia fructicolaorBotryotinia fuckelianafor further study and was determined to be new to science and a putative sister species toB. kiyoharaibecause of two apomorphic characters in males,viz., possession of a tail spikevsthe typical bursal flap, and the apparent absence of the P1 ventral single papilla, both typically plesiomorphic characters for the genus. Additionally,B. kiyoharaiis associated withX. serriatussuggesting that the host and microbiome associations that are shared between these two species, both of which are carried by ambrosia beetles, may have ecological and biological significance in their evolution and lineage radiation. Molecular phylogenetic analyses of the near-full-length small subunit (SSU: 18S) and the D2/D3 expansion segments of the large subunit (LSU: 28S) confirmed thatB. penain. sp. is very closely related toB. kiyoharaiwhich is a member of theB. fungivorusclade that includesB. thailandaeandB. willibaldi.Bursaphelenchus penain. sp. andB. kiyoharaiboth share very similar overall spicule morphology with theB. fungivorusclade. The new species is described and can be typologically differentiated fromB. kiyoharaiby the position of the hemizonid and excretory pore and its different geographical and host associations.