The antennal sensory array of the nocturnal bull ant Myrmecia pyriformis

•We describe in detail the sensilla on the antennal apical segment of Myrmecia pyriformis.•We present SEM images and descriptions of seven different types of sensilla.•We provide information on the distribution, size and numbers of the seven sensilla.•We compare our data with what is known about other ant species.

Insects use antennal sensilla to not only detect chemical and mechanical cues but also to sense changes in temperature, humidity and CO2 levels. Very little is known about the variation in numbers, size and structure of sensilla in ants. Here we describe in detail the array of sensilla on the apical segment of the antennae of the nocturnal Australian bull ant Myrmecia pyriformis. Using scanning electron microscopy techniques we identified eight types of sensilla: trichodea curvata, basiconica, trichodea, coelocapitular, chaetica, trichoid II, ampullacea and coeloconica. Mapping the spatial location of each sensillum revealed distinct distribution patterns for different types of sensilla which were consistent across different individuals. We found, in most cases, the number of sensilla increases with the size of the apical antennomere, which in turn increases with body size. Conversely, the size of sensilla did not appreciably increase with the size of the apical antennomere. We discuss the size, numbers and distribution of sensilla of M. pyriformis compared to other ant species. Lastly, given the inconsistent use of sensillum nomenclature and difficulties associated in reliable identification we have attempted to consolidate the ant sensilla literature to make possible interspecific comparisons.