A revision of the genus Chaetorellia Hendel (Diptera: Tephritidae) including a new species associated with spotted knapweed, Centaurea maculosa Lam. (Asteraceae)

Chaetorellia acrolophi sp. n. is associated with some European species of the subgenus Acrolophus of Centaurea. It is a potential biocontrol agent of some Acrolophus species that are adventive noxious weeds in North America. Ch. acrolophi sp. n. is described, and a key is provided to all nine species. The confirmed host-plants, knapweed, starthistles and related plants, belong to the genera Centaurea, Carthamus and Chartolepis (Asteraceae), and these are listed. Available biological data are reviewed, and some details of egg, larval and pupal morphology are described. Host-plant choice tests and canonical variates analysis were used to justify the separation of some species and to help identify some populations. The following nomenclatural changes are made (junior synonyms in brackets): Chaetorellia conjuncta (Becker) is removed from synonymy with Ch. succinea (Costa); Ch. hexachaeta australis Hering is raised to specific status; Ch. hestia Hering (=Ch. nigropicta Hering); Ch. loricata (Rondani) (= Ch. mara Hering and Ch. loricata septentrionalis Hering). Questionable synonyms include: Ch. australis Hering (?=Trypeta hexachaeta Loew); Ch. hestia (?= T. vittata Rondani); Chaetostomella cylindrica (Robineau-Desvoidy) (?= Tephritis algira Macquart, which is removed from Chaetorellia)