Morphology of the larvae of Arrenurus nodosus Koenike, 1896; A. knauthei Koenike, 1895 and A. stecki Koenike, 1894 (Acari: Parasitengona: Arrenuridae)

Abstract

The morphology of the larval stages of Arrenurus nodoslrs, A. knnirthei and A. stecki is described. Particular attention is paid to the different characters separating the three species. The larvae of the three species differ in the size and shape of the dorsal plate. Distinct differences appear between the proportions in the length of the lateral margins of the epimeres, which are similar in A. knnuthei and A. stecki, but different in A. nodosus. There are differences in the shape of the excretory pore plates. In A. stecki the shape of the anal plate is slightly different owing to the truncated proleg. The structure of the pedipalps are very similar. The PIIIl setae are always bipectinate, the PIVl is pectinate in A. knauthei and smooth in the other species, the PV6 is short and thick in A. nodosus, and long and thin in the other two species. Distinct differences also occur in the feathering of legs. The ITi8 seta is short in A. kna~lthei and long in the other two, the LITilO seta is long in A. nodosus and short in the other two, and IIITilO is thick and pectinate in A. nodosus, and smooth and fairly thin in the other two.