Struttura delle «aree sensoriali» antennali di alcuni Bostrichidi (Coleoptera)

Abstract

SUMMARY

STRUCTURAL OBSERVATIONS OF THE ANTENNAL<SENSORY AREAS> OF SOME BOSTRYCHIDAE.

Most species of Bostrychidae exhibit specialized sensory organs which consist in dense groups of basiconic sensilla on each segment of their antennal club. These sensory organs cover either flat or concave surfaces.

Observations have been carried out, in order to assess structural details on the antenna! clubs of the following species: Bostrychus capucinus L., Lichenophanes varius Illig., Amphicerus bimacu- latus (Ol.), Xylonites retusus Ol., Xylonites praeustus Germ., Scobicia chevrieri Villa, Sinoxylon sexdentatum Ol., Sinoxylon perforans Schr.

Three different arrangements of sensilla have been observed:

l) flat fields;
2) longitudinal grooves;
3) subspherical pits.

The borders of the flat fields are either entirely or partially contoured. Both flat fields of certain species and the subspherical pits are concealed beneath a group of layered marginal setae. No sex dimorphism was found.

The sensory areas occupy both faces of each antenna! segment. They are usually rwo on each face, although their number may be higher in some species.

With regard to the phylogenesis of these structures, it is suspected that both the longitudinal grooves and the subspherical pits originate from the flat fields by way of rwo separate evolutionary trends. Subsequently, they were masked by the marginal setae.

Possibly, Bostrychidae use these organs to search for their host-plants.

Viene esaminata la struttura delle aree sensoriali situate sulla clava antennale in otto specie di Bostrichidi. Vengono individuati tre tipi strutturali: campi piani, solchi longitudinali e fossette subsferiche. Si avanza l'ipotesi che solchi e fossette derivino da campi piani. Un'ulteriore complicazione strutturale, sopravvenuta, consisterebbe nella presenza di setole marginali.

Si propende nell'attribuire a queste strutture la funzione di percepire odori emessi dalla pianta ospite .