01597nas a2200169   4500008004100000245007800041210006900119260000800188300001000196490000700206520108700213100002001300700002301320700002401343700001601367856004401383       2007                        eng d00aHygroreceptors in the larva of Libellula depressa (Odonata: Libellulidae)0 aHygroreceptors in the larva of Libellula depressa Odonata Libell  cJun  a550-80 v533 aUltrastructural and electrophysiological (single-cell recordings) investigations were carried out on the coeloconic sensilla borne by the apical antenna of the larvae of Libellula depressa (Odonata: Libellulidae). These sensilla appear as pegs located in pits. One of them is a compound sensillum constituted of two fused pegs in a common pit and the other two are single pegs located in separated pits close to each other. Coeloconic sensilla show position and ultrastructural details very similar to those described in insect hygroreceptors. The electrophysiological recordings on the apical antennae of the last larval instar of L. depressa clearly show the presence of moist and dry cells responding antagonistically to humidity changes. This study gives the first evidence of hygroreceptors in dragonfly larvae and represents the first electrophysiological approach to larval sensilla of aquatic insects. The presence of hygroreceptors in L. depressa larvae is in agreement with the hygropositive response shown by these insects in laboratory and field behavioural experiments.1 aRebora, Manuela1 aPiersanti, Silvana1 aAlmaas, Tor, Jorgen1 aGaino, Elda  uhttps://odonatas.myspecies.info/node/3601859nas a2200157   4500008004100000245008500041210006900126260000800195300001100203490000700214520137700221100002001598700002301618700001601641856004401657       2008                        eng d00aThe antennal sensilla of the adult of Libellula depressa (Odonata: Libellulidae)0 aantennal sensilla of the adult of Libellula depressa Odonata Lib  cNov  a504-100 v373 aAn ultrastructural investigation (SEM, TEM) on the antennal flagellum of the adult of the dragonfly Libellula depressa (Odonata:Libellulidae) revealed sensilla located in pits on the lateral-ventral side of the antenna. These sensilla are represented by sensilla coeloconica and by deeply sunken sensilla. The sensilla coeloconica are innervated by three unbranched dendrites, which enter the peg and show a dendrite sheath ending at the base of the peg. The peg has no socket and its cuticle is irregular with wide pore-like structures at the base of which actual pores are visible. The structure of these coeloconic sensilla is in agreement with that reported for single-walled insect chemoreceptors. The deeply sunken sensilla are represented by two kinds of sensilla styloconica, named type-1 and type-2, located at the bottom of deep cavities appearing as simple openings on the antennal surface. These sensilla are no-pore sensilla with inflexible socket and unbranched dendrites and, notwithstanding their structural differences, share common features typical of thermo/hygroreceptors. The presence of chemoreceptors in adult dragonflies sheds light on evolutionary trends in insect perception; the previously unknown occurrence of thermo/hygroreceptors in dragonflies is very important in view of the reported ability of Odonata to thermoregulate heliothermically.1 aRebora, Manuela1 aPiersanti, Silvana1 aGaino, Elda  uhttps://odonatas.myspecies.info/node/16