Recharacterisation and photo-documentation of five North American Bursaphelenchus species from C.L. Massey’s type material

Abstract

The type specimens of fiveBursaphelenchusspecies described by Massey,i.e.,B. bestiolus,B. corneolus,B. elytrus,B. newmexicanusandB. wilfordi, were re-examined and photo-documented to update their descriptions in light of a contemporary understanding of the genus. The presence of a lateral field, basal swelling of stylet, P1 ventral single papilla of males and a pair of three-celled structures in females, which were not described or mentioned in the original descriptions, were observed, although the number of lateral incisures were not clarified because of sample condition. Within these five species, the intrageneric groupings ofB. bestiolusandB. wilfordihad been unclear. In the present study, because of newly observed morphological characters,B. bestiolusis considered to belong to thehofmanni-group, and is close toB. talonusandB. rufipennis. These three species form a species complex and are distinguished from each other only by female tail morphology. The species status ofB. wilfordiis still unclear, although, based on spicule morphology and structure and arrangement of genital papillae, we consider it to belong to thehofmanni-group, close toB. parvispicularis,B. paraparvispicularisandB. osumiana. However, female characters ofB. wilfordiare also similar to members of thecocophilus-group andParasitaphelenchus. Re-isolation and molecular identification are necessary to confirm the status of these species. By contrast, the affiliations ofB. corneoluswith thehofmanni-group andB. elytrusandB. newmexicanuswith theeggersi-group were confirmed. Based upon its morphological traits,B. corneolusis close toB. gerberaeandB. paracorneolus, and is distinguished from these species by its spicule morphology, female tail morphology and female post-uterine sac length. However, male specimens ofB. corneoluswere not available for the present study and confirmation is necessary.Bursaphelenchus elytrusis similar toB. tusciaeand is distinguished from it by its spicule (condylus) morphology and excretory pore position.Bursaphelenchus newmexicanusis close toB. glochisand is distinguished from it mostly by morphometrics and spicule (condylus) morphology. However, morphometrics usually vary among individuals and populations of a species, necessitating morphometric and molecular comparisons of more isolates (strains) in order to clarify specific status.