S. Mahunka szerk.: Folia Entomologica Hungarica 58. (Budapest, 1997)

tergite II counting either three (in 47 European species), or four such setae (in 24 species). Regarding the number of setae in the distal half of the anterior vein of the fore wing, there are generally three different arrangements, even if these are somewhat variable too: 1) Row of setae complete, no distinct gap near vein furcation; sometimes setae irregularly placed leaving a small gap here and there. 2) 5-12 distal setae, a distinct but mostly short gap behind the vein furcation, sometimes only 4-6 widely spaced setae. 3) Three distal setae (1+2) after a wide gap behind vein furcation, sometimes four (2 + 2), or only two distal setae. The distribution of distal setae on fore wings in Thrips species is indicated in Table 2. As far as the presence or absence of campaniform sensilla is concerned, only those on metanotum and on tergite IX are usually of some taxonomical relevance. In Thrips major Uzel (1895: 179) from Central and Western Europe, for an example, the metanotal sensilla are mostly wanting. But in specimens from the Eastern Mediterranean and the Near East these sensilla are occasionally present. DISCUSSION The relevance of characters As indicated above, the presence or absence of sternal discal setae is regarded as the decisive pair of a character for a division of the whole bunch of species into two main taxonomical groups (A, and B, see above). Not all the species included in one of the two groups are necessarily closely related. But how closely related are they? The next question in this context is that for the valence of the secondary characters, and this not only in the sense which of them are eidonomically more useful, but also which are possibly of a "higher" taxonomical relevance than others. In order to determine the rank of the valence of a character, some phylogenetical reflections have to be undertaken. The reduction, or complete loss, of certain morphological structures or dispositions is commonly regarded as being derived. In any given group of species such reductions and losses occur in different combinations of characters. The same species exhibit also ancestral features, and here too, in variable combinations. The consequent question remains open which of the ancestral characters are "older" than others, and contrary, which of the derived ones are "younger" than others. The hairy European Thrips minutissimus demonstrates exemplarily to have both types of characters. Thrs species shows among the mostly used diagnostic features not only those which might be regarded as ancestral (listed under "a"), but also those which are likewise advanced (listed under "b"), as follows: a) Anterior vein of fore wing in its distal half with 7-12 setae (the majority of species in Thrips has three distal setae); tergite II near lateral margin with four setae (instead of three); pleurotergites 111

—V11 each with a few discal setae (instead of none); hind margin of tergite VIII with complete comb of microtrichia (instead of an incomplete comb, or of none); sternites III-VII with numerous discal setae (instead of none). b) Campaniform sensilla on metanotum wanting (instead of being present); hind margin of pronotum with three pairs of postero-marginal setae (instead of four); anterior tar-