Two halacarid mites viz. Copidognathus australensis (Lohmann, 1909), and Rhombognathus validipes Bartsch, 2000 are reported from India for the first time. Copidognathus australensis was collected from Chatham Island (Andaman Islands) and Rhombognathus validipes was collected from Wandoor, South Andaman (Andaman Islands) and Mus Island (Nicobar Islands). Earlier records of these species were from Australia.
An updated overview of sexual dimorphism in halacarid mites is presented in this paper. Males and females of halacarid mites morphologically differ in the genital region. Additionally, sexual dimorphism can be seen in some species in dorsal plates, ventral plates, chaetotaxy of legs, idiosoma, gnathosoma, which is the theme of the present paper. A distinction of males vs. female mites is someti - mes reflected in size and fusion of various idiosomal plates and width of cuticular membranous areas. Other sexually dimorphic characters such as paragenital are - olae, postgenital papillae, lamella in legs, fossary setae on tarsus found in some species of halacarids are also discussed
The present study reports a new distribution record for the halacarid mite Acarothrix palustris Bartsch, 1990 on mangrove pneumatophores from Goa, India. Earlier this species was known from Hong Kong and Singapore (West Pacific Ocean). The present report represents the first record of the species from the Indian Ocean.