Ultrastructural features of the midgut of Rhinocricus padbergi (Diplopoda: spiroboida)

The midgut epithelium of the milipede Rhinocricus padbergi has been reported to be stratified or pseudostratified, and there is evidence that this region of the intestine is lined by a single layer of absorptive epithelial cells interspersed with smaller regenerative cells. In this work, transmission electron microscopy was used to study the structure and organization of the midgut of R. padbergi. The midgut was lined by a pseudostratified epithelium in which all of the cells were in contact with the basement membrane but did not necessarily reach the apical surface. The epithelium contained three cells types, namely, absorptive cells with apical microvilli that gave the midgut epithelium a "brush border" appearance, secretory cells that were interspersed with the absorptive cells and probably served to lubricate the epithelial surface, and regenerative cells located in the basal region of the epithelium. This organization of the gut cells in R. padbergi was similar to that of other arthropodes.

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

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.