Schistonchus (Aphelenchoididae) from Ficus (Moraceae) in Australia, with description of S. aculeata sp. n.

Abstract

A checklist of Schistonchus collected from Ficus spp. in Australia and stored in the Waite Nematode Collection at the University of Adelaide is presented. Within Australia, Schistonchus contains 12 morphospecies and four nominal species, based on a combination of the following characters: body shape when heat-relaxed, position of excretory pore, length of post-uterine sac, spicule form, and number and position of caudal papillae. Up to four morphospecies of Schistonchus have been collected from one species of Ficus and, in several cases, one morphospecies of Schistonchus has been collected from more than one host fig species. A phylogenetic tree based on D2/D3 sequences showed that Australian collections of Schistonchus fall into two clades, suggestive of endemic and introduced lineages with host switching. Schistonchus aculeata sp. n. is described from F. aculeata and F. opposita and differentiated from other species of Schistonchus by having the excretory pore opening near the lips, a short post-uterine sac, rosethorn-shaped spicules, arcuate gubernaculum or thickening of dorsal wall, amoeboid sperm, and three pairs of caudal papillae (one pair adcloacal, one just posterior to mid-tail, and one near the tail tip), association with Kradibia spp. pollinating wasps and apparent biogeographical range. A key to the known species and morphospecies of Schistonchus from Australia is presented.