The wheat thrips, Haplothrips tritici, is known from across eastern Europe and adjoining areas of Asia into western Europe and north Africa, and is widely regarded as a pest of cultivated cereal crops, particularly of Triticum but also of Hordeum (Özsisli 2011). The identity of this thrips species is not in doubt, but a closely similar species, Haplothrips cerealis, was described from Egypt (Priesner 1939), and subsequently recorded between southeastern Europe and Iran (see Minaei & Mound 2008). Priesner based this species on an unspecified number of specimens of both sexes, collected from the ears of cultivated wheat at "Wadi Gederât, Sinai", and did not designate a holotype. Minaei and Mound (2010) indicated that they considered the records of cerealis from Iran to be based on misidentifications of tritici, but they suggested that further studies were required to determine if there is any evidence that these names represent different species in other countries. The problems arise because the published descriptions of, and comparisons between, the two species are confusing and sometimes contradictory. The objective of this report is to examine the published literature, and to consider this in relation to observed structural variation in recently collected samples as well as specimens in museums that are variously labeled as one or other of these two species.
Literature references to femalesThe original description (Priesner 1939) states that cerealis differs from tritici in having shorter postocular, prothoracic and abdominal setae that are sharply pointed, whereas those of tritici are rounded at the tip, and that cerealis also differs in the shape of the male aedeagus. Subsequently, Priesner (1950) provided a key to the world species of Haplothrips, but the choices involved in this are confusing with cerealis emerging at one couplet only, but tritici emerging at five different couplets. At couplet 60(85) the choice is "Major bristles blunt, at least basal wing bristles 1 and 2 blunt or knobbed", with the contrasting choice "Epimeral and basal wing bristles (at least b.2 and 3) sharply pointed". The first choice will lead to tritici (plus some other species), and this agrees with Priesner's 1939 statement above. The second choice at couplet 60(85) will lead to 15 species, of which the final pair is tritici and cerealis (couplet 113/114) with tritici stated to have "Prothoracic and basal wing bristles nearly knobbed", but cerealis to have "Major bristles slightly blunt". Thus the choice leading to cerealis at couplets 60(85) (sharply pointed) contradicts that leading to this species at 113(114) (slightly blunt). Later couplets in this key indicate that tritici has the major setae "not quite sharp" or "narrowed toward blunt tip, not distinctly knobbed". Thus this key does not function to distinguish cerealis females from those of tritici.Despite the problems indicated with the 1950 comparison, in a subsequent key to the Haplothrips species of Egypt, Priesner (1965) distinguished the two species at couplet 47(52) ...