THALASSARACHNA BASTERI (ACARI, HALACARIDAE), DESCRIPTION OF EXTERNAL CHARACTERS OF LARVA, NYMPHS AND ADULTS AND OUTLINE OF DISCRIMINATING CHARACTERS OF LARVAE

Thalassarachna basteri is a species widespread in the North Atlantic, in the course of an annual life cycle it runs through one larval and two nymphal instars until the adults hatch. The development of external morphological characters from the larval to adult state is described. It proved to be similar to that known about other genera. Larvae in general have smaller plates, an incomplete number of setae on the venter and the legs, and shorter legs than the following instars. The larvae of T. basteri have almost the same shape and the same number of setae on idiosoma, gnathosoma and legs as larvae of northern hemisphere genera similar in size and sharing the habitat and life-style. Beside that the larval ocular plates of T. basteri are divided into an anterior and posterior platelet, still more generic differences exist, these are outlined.