Morphology of the larvae of three species of Arrenurus (Acari: Parasitengona: Arrenuridae)

Abstract

Morphology of the larval stages of Arrenurus sinuator (O. F. Müller, 1776), Arrenurus bifidicodulus Piersig, 1897, and Arrenurus perforatus George, 1881 is described. Particular attention is paid to the characters differing between the three species. Larvae of the three species differ in the size and shape of the dorsal plate, although the proportions of their length and width are the same. Distinct differences appear between the proportions in the length of the lateral margins of the epimers. In A. sinuator and A. perforatus the shape of the anal plates is very similar, the only difference being a small process on the posterior margin of the plate. In A. bifidicodulus the shape of the anal plate is slightly different owing to the truncated anterior margin. The structure of the pedipalps also differs. The PIII1 setae are always bipectinate but they are distinctly thicker in A. sinuator and A. perforatus. In A. sinuator PV4 and PV5 setae are bipectinate, in A. perforatus PV3, PV4 and PV5 setae are pectinate, and in A. bifidicodulus the PV3 seta is pectinate. Distinct differences also occur in the feathering of legs. Above all, in A. perforatus on the tarsus of leg pair III one more seta was observed and marked as IIITa8. The present description of the larval A. sinuator is compared to that given by Stechmann (1977) and the description of the larval A. bifidicodulus is compared to that given by Cichocka (1980).

Keywords:

• Acari
• Arrenurus bifidicodulus
• Arrenurus perforatus
• Arrenurus sinuator
• larvae
• morphology
• water mites

Acknowledgements

I thank E. Biesiadka for consultation. Financial support was provided by Komitet Badań Naukowych in 2004–2007 (research grant no. 2P04C10527).