The evolution of a myrmecophilous lifestyle in beetles is often associated with morphological alterations. In particular, the antennae of all members of the myrmecophilous ground beetle tribe Paussini are greatly modified, with flagellomeres flattened or crassate, frequently reduced in number from 9 to 5 or even 1 single “antennal club”. The enhanced glandular function of the an-tennal club has been recently described by scanning (SEM) and transmission (TEM) electron mi-croscopy in Paussus favieri Fairmaire, 1851, where the antenna has become a complex glandular organ, supplying rewarding substances to the ants. In the present work, the antennal sensilla of P. favieri are investigated by SEM, TEM and Focused Ion Beam (FIB/SEM) technology. Most sen-silla of scape and antennal club are highly modified mechanoreceptors (i.e. multipointed, fringed, branched, brush-like, sickle-shaped), singly or grouped in tufts (“antennal symphilous organs”). These “trichomes”, here assigned to 8 different morphotypes of sensilla chaetica (Ch.1– Ch.8), show a variable number of basal pores (present also at the base of the taste sensilla Ch.9), which spread dense substances of unknown chemical composition on the seta. Although hygro-, ther-mo- and chemoreceptors are reduced in number as compared with non-myrmecophilous rela-tives, and mainly relegated to the apex of the antennal club, their diversity is comparable to that of other carabid beetles: two types of sensilla trichodea (Tr.1– Tr.2); three types of basiconica (Ba.1– Ba.3); one type of campaniformia (Ca); one type of coeloconica (Co) and one type of Böhm sensilla (Bo). Contrary to the hypothesis that Paussus species lack a Johston’s organ, a non-connective chordotonal organ composed of 9 groups of scolopidia has been found inside the pedicel. A comparison between sensilla of P. favieri and those of other non-myrmecophilous and myrmecophilous ground beetle species is provided.

DI GIULIO, A., Maurizi, E., ROSSI STACCONI M., V., Romani, R. (2012). Functional structure of antennal sensilla in the myrmecophilous beetle Paussus favieri (Coleoptera, Carabidae, Paussini). Corresponding author. MICRON, 43(6), 705-719 [10.1016/j.micron.2011.10.013].

Functional structure of antennal sensilla in the myrmecophilous beetle Paussus favieri (Coleoptera, Carabidae, Paussini). Corresponding author

DI GIULIO, ANDREA
;
2012-01-01

Abstract

The evolution of a myrmecophilous lifestyle in beetles is often associated with morphological alterations. In particular, the antennae of all members of the myrmecophilous ground beetle tribe Paussini are greatly modified, with flagellomeres flattened or crassate, frequently reduced in number from 9 to 5 or even 1 single “antennal club”. The enhanced glandular function of the an-tennal club has been recently described by scanning (SEM) and transmission (TEM) electron mi-croscopy in Paussus favieri Fairmaire, 1851, where the antenna has become a complex glandular organ, supplying rewarding substances to the ants. In the present work, the antennal sensilla of P. favieri are investigated by SEM, TEM and Focused Ion Beam (FIB/SEM) technology. Most sen-silla of scape and antennal club are highly modified mechanoreceptors (i.e. multipointed, fringed, branched, brush-like, sickle-shaped), singly or grouped in tufts (“antennal symphilous organs”). These “trichomes”, here assigned to 8 different morphotypes of sensilla chaetica (Ch.1– Ch.8), show a variable number of basal pores (present also at the base of the taste sensilla Ch.9), which spread dense substances of unknown chemical composition on the seta. Although hygro-, ther-mo- and chemoreceptors are reduced in number as compared with non-myrmecophilous rela-tives, and mainly relegated to the apex of the antennal club, their diversity is comparable to that of other carabid beetles: two types of sensilla trichodea (Tr.1– Tr.2); three types of basiconica (Ba.1– Ba.3); one type of campaniformia (Ca); one type of coeloconica (Co) and one type of Böhm sensilla (Bo). Contrary to the hypothesis that Paussus species lack a Johston’s organ, a non-connective chordotonal organ composed of 9 groups of scolopidia has been found inside the pedicel. A comparison between sensilla of P. favieri and those of other non-myrmecophilous and myrmecophilous ground beetle species is provided.
2012
DI GIULIO, A., Maurizi, E., ROSSI STACCONI M., V., Romani, R. (2012). Functional structure of antennal sensilla in the myrmecophilous beetle Paussus favieri (Coleoptera, Carabidae, Paussini). Corresponding author. MICRON, 43(6), 705-719 [10.1016/j.micron.2011.10.013].
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Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/11590/153742
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