Abai, MR

6th International Congress of DipterologyComparative morphology of “Sturmia-spots” in maletachinids – first results (Diptera: Tachinidae)Cerretti, P. (1), A. Di Giulio (2) & M. Scalici (2)(1) Centro Nazionale Studio e Conservazione Biodiversità Forestale – Corpo Forestaledello Stato, Via Carlo Ederle 16/a, 37100 Verona, Italy. Email:pierfilippocerretti@yahoo.it(2) Dipartimento di Biologia, Università degli Studi “Roma Tre”, Viale G. Marconi, 446,00146 Roma, Italy. Email: digiulio@uniroma3.it; scalici@uniroma3.itSturmia-spots (also referred to in the literature as “patches of appressedhairs”) are hairy areas variable in shape and size, situated in variouspositions on the abdominal tergites (3–5) of some genera of Exoristinaeand in the phasine genus Besseria. Though used by taxonomists asdiagnostic features, these structures have never received much attentionconcerning their morphology and biological function.A careful observation of these structures in many specimens of differentspecies and genera showed that the appressed hairs are glued together byviscous substances (often crystallized), hence the hypothesis of a possibleglandular function of these areas. This hypothesis represented the startingpoint of the present comparative morphological and histological study ofthese structures in 7 genera and 13 species.The fine morphological analysis carried out by SEM highlighted a greatvariety of different types of spots. In most cases they appear as more orless depressed areas of the cuticle, well distinct and rounded; otherwisethey are wide and scarcely defined, occupying part or most of the ventral,lateral and dorsal surface of the tergites, or they arise from non-depressedareas. All types are characterized by modified setation, composed bybrushes of elongate and thick setae or by thinner, shorter setae, set moretightly together than normal. All setae are deeply corrugated longitudinallylike the setae external to the spots. Close to the base of each seta, andslightly anteriorly, a glandular area composed by a variable number ofsmall pores is evident (this area is present only at the base of setae formingthe spot); curls of whitish substance have been observed emerging fromthese pores. The spots show a microsculpture that can be more or less38