S. Mahunka szerk.: Folia Entomologica Hungarica 58. (Budapest, 1997)
Chaetotaxis has largely been considered by recent authors. The main species groups as differentiated and discussed by Palmer (1922: 8, 20, 60) are based chiefly on characters of the chaetotaxis. The author recognizes five "relatively distinct taxonomic groups 1 ' which "do not necessarily reflect phylogenetic relationships", ...although there might be "some phylogenetic significance". In recent literature the most important division of the species into groups is referred to either the presence of discal (= accessoiy, Hood 1932: 123; Priesner 1964a: 108) setae on the sternites, or their absence. This pair of a character used in taxonomy has turned out to be remarkably stable in the genus. Among the 71 species occurring in Europe and the Mediterranean, discal setae on sternites are present in females of 35 species (signified here as group A), but are absent in 36 species (group B). The presence of discal setae on sternites can eidonomically be further specified in so far as in five of the species of group A the sternite VII regularly lacks those setae, whereas the majority of 30 species have them. The next pair of a significant character to sort out smaller groups within the two main groups (A, B) is the presence/absence of discal setae on pleurotergites. There are 16 species in group A, and 3 species in group B possessing discal pleurotergal setae. Among the 14 European Thrips species having 8-segmented antennae, ten (71.4%) show discal setae on both sternites and pleurotergites. Contrary to this, the corresponding figure in the species with 7-segmented antennae is five (9.2%) out of 54 species (three further species are exotic and occasionally introduced). Table 2. Number of distal setae on anterior vein of fore wing in macropterous females of the European species of Thrips in comparison with the appropriate data in the species from other regions. The total number of species considered is: Europe (71), Asia and Pacific (89), America (58), Africa (15) Region Number of distal setae Number of species Europe (4-) 5-15 4 2 or 3 16 1 54 Asia and Pacific (Palmer 1992) 5-15 28 4 or 5 6 3 (-4) 48 2 7 America (Nakahara 1994) 5-12 4 4 or 5 2 3 (-4) 45 2 or 3 7 Africa (Hood 1932) 5-10 3 3 12 Taxonomically somewhat less reliable characters are the number of setae in certain positions on some sclerites as well as the presence/absence of campaniform sensilla on the metanotum. As to the number of setae, the hind margin of the pronotum exhibits in Thrips normally three or four pairs of postero-marginal setae, rarely only two pairs; sometimes there is on one side one seta less, or vice versa, there are one or two setae additionally. Somewhat more regular is the number of lateral setae at the side margin of
