New findings on Daidalotarsonemus and Excelsotarsonemus mites around the world (Prostigmata: Tarsonemidae)

Daidalotarsonemus and Excelsotarsonemus are tarsonemid genera commonly found in the canopies of rainforests. The first one comprises 25 described species and it is one of the few tarsonemid genera occuring worldwide. Excelsotarsonemus, on the other hand, is a poorly known genus with just three described species from Central America. The taxonomy of these taxa has been supported by a poor morphology understanding, based mainly in Phase Contrast Microscopy, leading to the misinterpretation of the characters and erroneous identifications. This way, Phase Contrast (PC), Differential Interference Contrast (DIC) and Low Temperature Scanning Electron Microscopy (LT-SEM) techniques were used to analyze specimens of these two genera deposited several museums around the world. Twenty five new species of Daidalotarsonemus from the Americas, Asia and Oceania and three new species of Excelsotarsonemus from South America were discovered in the study. It was found that the geographical distribution of D. tessellatus is much smaller that it was noticed before, being limited only to North America. Based on the position of setae c1 and shape of the tegula of the females, it was determined that Daidalotarsonemus can be split in two species groups. Similarly, Excelsotarsonemus can be divided in two groups based on the modifications in the e and f setae in females. Using the LT-SEM, it was observed for the first time a wax-like substance covering the tegument in both genera. Fungi, lichen and bacteria were often found attached to the wax substance, fact that has important biological and agricultural implications. Both genera, especially Excelsotarsonemus, have some dorsal setae (d-e-f ) with very broad and intricate folding patterns. These sail-like setae probably allow the mites to become airborne, glide within the forest canopy and colonize new trees.

Key-words: Taxonomy, canopies, rainforest, LT-SEM.

S.A. Financial Support: FAPESP.