Animals are depicted next to the corresponding antennal SEM images. (A) Detailed view of the antennae of L. y-signata. The proximal part of the antennae is not only covered with sensilla, but also scales. Glands (g) are highly abundant on the antennae. Many mechanosensory sensilla (S.ch.: Sensilla chaetica) were arranged in circles on the antennal segments. On some antennal segments gustatory sensilla (arrows) can be found between the S.ch (for further information read Missbach et al., 2011). Very rarely zero to four olfactory Sensilla basiconica were identified per segment, in a mostly redundant pattern on the antennae with similar numbers of olfactory sensilla and sensilla types on each antennal segment. Antennal segments are separated by antennal breaking points. The pattern of sensilla is modulated by increasing the number of annuli of a segment through molting. (B–E) Different morphological types of basiconic sensilla. No grooved sensilla/olfactory coeloconic sensilla were identified on the antennae. Only small pegs surrounded by a cuticular wall (s. coe.; referred as coeloconica-like sensillum, Bockhorst 1988) were located on the antennae. These sensilla are not olfactory (for detailed external morphology see Missbach et al., 2011). (F) Detailed view of the antennae of T. domestica. The antennal organization is similar to the bristletail, with antennal breaking points and lifelong molting. The most abundant sensilla on the antennae again are mechanosensory S.ch.; beside those gustatory and olfactory sensilla are distributed in a species-specific modular manner over the antennae. (G) In contrast to L. y-signata, grooved sensilla can be found on the antennae of T. domestica. (H and I) Different morphological types of basiconic sensilla. (K and L) Gender specific differences between a female (K) and a male (L) antennae of P. siccifolium. Female antennae are short and lack trichoid sensilla (S.tri.). They more or less lack sensilla on the proximal annuli, only the last two annuli are covered with a high number of olfactory and also some mechanosensory sensilla (S.ch.). (M) Male antennal tip. Similar to the distal female antennal annuli the highest density of sensilla can be found on the last annuli. (N and O) Both grooved and pored sensilla can be found on these segments. Scale bars: A: 50 μm; B, C, D, E, H, I, N, O: 2 μm; F: 100 μm; G: 1 μm; K, L: 200 μm; M: 20 μm.