Comparative morphology and moulting of sensilla basiconica of Lepisma saccharina linnaeus (Zygentoma: Lepismatidae) and Machilis sp. (Archaeognatha: Machilidae)

Comparative morphological studies of the different types of sensilla basiconica of Lepisma saccharina (Zygentoma: Lepismatidae) and Machilis sp. (Archaeognatha: Machilidae) revealed 3 types in Machilis (sensillum basiconicum types A–C) and 4 types in Lepisma (sensillum basiconicum types D–G). No-pore sensilla (sensillum basiconicum types A, B and D) were found in both species. The organization plan corresponds to that of no-pore sensilla of pterygotan insects. Original characters are doubled basal bodies and a larger number of sense cells. L. saccharina possesses both single-walled (sensillum basiconicum types F and G) and double-walled sensilla (sensillum basiconicum type E). Machilis possesses only single-walled sensilla (sensillum basiconicum type C). For the first time a double-walled sensillum is described in apterygotan insects. The sensillum basiconicum type E is a typical double-walled sensillum but with only one circle of spoke canals near the tip of the hair shaft. A sensillum with spoke canals, but with a single wall, is also found in L. saccharina (sensillum basiconicum type G). The organization plan of the multiporous sensilla with pore tubules of Lepisma and Machilis corresponds to that of the multiporous sensilla of pterygotan insects. Sensillum basiconicum type F of Lepisma shows a peculiarity in that it is a “doubled sensillum”. All sensilla basiconica described in both Lepisma and Machilis have 4 enveloping cells and the position of the moulting porus is at the tip of the hair shaft.