External morphology of the antennae of Rhinocricus padbergi Verhoeff, 1938 (Diploda, Spirobolida)

ABSTRACT

The antennae of millipedes (Diplopoda) have an important role in detecting various types of enviromental stimuli. The structural organization of the antennae is closely related to the degree of sensorial perception. The antennae generally consist of eight segments, the most distal (apical) of which characteristically contains four cone-shaped sensilla. In this paper, we describe the external morphology of the antennae of the diplod Rhinocricus padbergi. Antennae from anesthetized mael and female millipedes were fixed in Karnovsky solution and processed for scanning electron microscopy. Intraspecific variation was observed in the number of apical cones (13-18) in segment VIII. This number of cones differed from that usually found (4) in other millipedes species. Segments I, II and III lacked sensilla while the remaining segments had different types of sensilla, including trichoidea, chaetica and basiconica. The presence of the latter types of sensilla suggests that R. padbergiantennae have chemoreceptor, mechanoreceptor and thermal/ hygrosensitive functions, respectively.