First record of Fergusonina (Diptera: Fergusoninidae) and associated Fergusobia (Tylenchida: Neotylenchidae) forming galls on Metrosideros (Myrtaceae) from New Zealand

Abstract

A new species of fly, Fergusonina metrosiderosi Taylor sp.n. (Diptera: Fergusoninidae) [and its associated nematode, Fergusobia pohutukawa Davies sp.n. (Tylenchida: Neotylenchidae)], is described from unilocular basal shoot-bud galls on Pohutukawa (New Zealand Christmas Tree), Metrosideros excelsa Banks ex Gaertn. (Myrtaceae). The fly is characterized by the short, sclerotized postabdomen of the female, distinctly grey wings, reduction in length of the reclinate orbital, postocellar and vertical setae, undifferentiation of the ocellar setae, supernumerary setation of the genae, and three pairs of scutellar setae rather than two. The dorsal shield is restricted to a few raised sclerotized spicules on the first to third thoracic segments of the larva and epidermis of the puparium. The nematode is characterized by the combinations of arcuate shape, small ‘a’ ratio, swollen cuticle, small cephalic region with elevated circum-oral area with a flat tip, coarse annulation and relatively slender conical tail of the parthenogenetic female, and coarse annulation, long bursa and angular spicule with short, broad, offset manubrium of the male. Fergusonina metrosiderosi sp.n. and Fergusobia pohutukawa sp.n. represent the first record of the fly-nematode association from the host genus Metrosideros, and the first record from New Zealand. Aspects of the biology and biogeography of the fly-nematode association are discussed.