(a) Map of La Réunion Island showing the locations included in this study and the nematode lineages [10] isolated from them (modified from openstreetmap.org, © OpenStreetMap contributors). (b) Unrooted neighbour-joining phylogenetic tree for La Réunion P. pacificus strains analysed in this study and the reference strain, RS2333. Colour code refers to the lineage of the strains: yellow, clade A; red, RS2333 (clade A); blue, clade B; orange, clade C; green, clade D. (c) Clumping/bordering assay for the P. pacificus RS2333 strain, which shows a solitary behaviour under laboratory conditions, characterized by low levels of clumping and bordering. (d) Clumping/bordering assay for the P. pacificus RSB001 strain, isolated at 2327 m.a.s.l., which shows strong clumping and bordering behaviours under laboratory conditions.