Basalt and Balaustiinae (Acarina: Parasitengona: Erythraeidae)

John Clark *1

1 Christchurch Polytechnic Institute of Technology

The larvae of Balaustium mites are non-parasitic members of the Parasitengona. Balaustium larvae feed on pollen and small arthropods. Although the genus is poorly known in New Zealand, it is a widespread saxicole on Banks Peninsula and in Canterbury braided river beds. Recent work on Banks Peninsula revealed communal egg-depots in rock crevices. Rock crevices under basalt rinds are particularly well suited to holding 1,000+ eggs. In addition, these sub-rind refuges are used for moulting. Basalt rinds are often easily removed with a small steel lever allowing the collection of large numbers of eggs or prelarvae as well as pupa I & II. The collection of pupa I with their adhering larvae pelts is providing a way to link the heteromorphic larvae with post larval forms. The collection of large numbers of prelarvae near eclosion in our austral 2014 Spring from many locations in Canterbury and Banks Peninsula has provided material for taxonomy and other studies. Other Balaustiinae genera found as pupae under basalt rinds included Abrolophus and Wartookia. Rind refuges may be ancient: they are often replaced with an adhesive.  

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