The thistle flies of the genus Chaetostomella (Diptera: Tephritidae: Terelliini) from Morocco, with a reference to European and Asian fauna.

The genus Chaetostomella Hendel, 1927 (Diptera: Tephritidae) in the fauna of Morocco is reviewed based on integrative morphological and molecular analyses. Phylogenetic reconstruction using a 657 COI barcoding sequences strongly supports the monophyly of the genus and resolves Chaetostomella steropea as the basalmost lineage, sister to the recently radiated Chaetostomella cylindrica species complex. Two species, Chaetostomella kitaneasp. nov. (reared from Cynara scolymus and Carthamus pectinatus), and Chaetostomellamaroccanasp. nov. (reared from Mantisalca salmantica and Ptilostemon rhiphaeus) are described. Despite showing low genetic divergence from C. cylindrica, which indicates their evolutionary youth, both new species exhibit stable diagnostic morphological characters and geographic isolation. Chaetostomella steropea (Rondani, 1870) is redescribed based on specimens reared from Chamaeleon gummifer, representing its first record for North Africa. Tephritis algira Macquart, 1843 is considered a nomen dubium. A preliminary key to the species of Chaetostomella and remarks on the morphology, distribution and examined material of some little-known non-Moroccan species are provided.