The variability of antennal sensilla in Naucoridae (Heteroptera: Nepomorpha)

Abstract

The morphology and distribution of sensilla on the surface of the antennae of the naucorids’ species were studied via scanning electron microscopy. Eleven types of sensilla were identified regarding specific sensory modalities, based on their cuticular morphology. Cuticle morphology identifies five types of sensilla trichodea, four types of sensilla basiconica, one type of sensillum coeloconicum and sensillum ampullaceum. Three new types of mechanosensitive sensilla were found. Moreover, the morphological diversity between the antennae allowed the distinction of ten different antennal types that correspond to different sensillar sets. The sensilla found in Naucoridae share similarities with the sensilla of other nepomorphan taxa, as well as of terrestrial insects. However, no sensillar synapomorphy was found between Naucoridae and Aphelocheiridae.

Morphology of the Antennal Sensilla of Notonectoidea and Comparison of Evolutionary Changes in Sensilla Types and Distribution in Infraorder Nepomorpha (Insecta: Heteroptera)

“…Apart from morphological variations among sensilla types, there is also an important variability in the incidence, density, and distribution of the different types of sensilla among different insect species (e.g., Hymenoptera) even within a single genus, and between sexes within a species [22,23]. Similar variations in types, density and distribution of sensilla have also been observed in the studied taxa of the nepomorphan species [24][25][26][27]; however, their phylogenetic effects are still little explored. In addition to the putative phylogenetic effects on such variability (as in Hymenoptera's species, for instance [28]), the diversity, density, and distribution patterns of sensilla may be the product of interacting selection pressures related to feeding and foraging habits, habitat type, mating systems [29][30][31] and the insects' systematic position.…”

“…Chaika and Sinitsina [32] found a few types of sensilla trichodea in Notonecta glauca, including the oar-like sensilla that is designated to ST4 in our studies. Such extended (in comparison to the rest of sensory structures) sensilla have not been observed in previously studied nepomorphan taxa [24][25][26][27]. Their shape and size suggest they might be used to recognize the vibrations of water waves.…”

“…However, some of the previous studies on nepomorphan antennal sensilla deal with only one or a few species [32], making it difficult to compare sensilla within taxonomic groups. Ultramorphology on the antennal sensilla of the nepomorphan superfamily has been conducted systematically in several studies [24][25][26][27], using a consistent terminology for the sensilla types. A previous study on the antennal sensilla of one family of Pleidae (Notonectoidea) was presented by Garza et al [33].…”

“…These sensilla have been analyzed regarding evolutionary aspects based on the currently studied taxon (Notonectoidea) and the previously available data on Nepomorpha, after Nowi ńska and Bro żek [24,25,27], Nowi ńska et al [26] and data on Gerromorpha, after Nowi ńska and Bro żek [35]. The morphological cladistics analysis of the antennal sensilla of Nepomorpha was performed on a phylogenetic program of Tree Analysis Technology TNT and Winclada.…”

“…The basic morphology of the antennal sensilla as well as the ultrastructure of the receptors of several taxa of the infraorder Nepomorpha were studied by Chaika and Sinitsina [32]. More detailed studies on the morphologies, distributions and functions of antennal sensilla were conducted in a systemic approach, based on numerous species of Nepidae, Belostomatidae [24], Aphelocheiridae, Ochteridae, Gelastocoridae [25], Corix-idae, Micronectidae [26] and Naucoridae [27]. Moreover, Garza et al [33] published research on the antennae and sensilla of some species of Pleidae, with an emphasis on their morphologies and suspected functions.…”