oa Annals of the Natal Museum - African Trombiculidae (Acarina). 2. The genera Eutrombicula Ew. And Sauriscus Lawr., with description of a new subgenus, Squamicola

Volume 15, Issue 13
  • ISSN : 0304-0798



The genus Eutrombicula was first raised by Ewing (1938) with the common North American pest-chigger E. alfreddugesi (Ouds.) (Trombicula irritans of authors) as the type species. He distinguished this genus from Trombicula on two characters: the division of the palpal claw into only two prongs, and the presence of less than 30 body-setae on the dorsum, in the larvae. Later, Ewing (1943) separated off a genus Acariscus: the synonymy of this, and a general account of Eutrombicula, were dealt with by Michener (1946) and Fuller (1952). Subsequently, it became difficult to separate Eutrombicula at the generic level from various species of Trombicula Berl., sensu lato, and Eutrombicula was thenceforth usually regarded as a subgenus of Trombicula. It was so treated in the checklist of world chiggers of Wharton and Fuller (1952). The post-larval stages of Eutrombicula species typically have parasensillary eyes, that is, eyes placed close to and immediately posterolateral to the sensillary bases. On the basis of a particular interpretation of the original drawings of Trombicula minor Berl., the type of the genus Trombicula, known only from adults, Womersley (1952) assumed that the adults of T. minor possessed parasensillary eyes. He therefore sunk what was known as Eutrombicula in his newly-interpreted subgenus Trombicula. This was later rectified by Womersley and Audy (1957). In 1954, Dr. R. F. Lawrence very kindly lent his large collection (new species descriptionbed by Lawrence, 1949, 1951) to one of us (J.R.A.) and also gave permission and encouragement to have the batch-slides remounted, one chigger per slide, so that holotypes could be kept together and paratypes be available for distribution. Accompanying the type slides was a quantity of tubed material. Dr. Zumpt and Dr. Lawrence also sent a number of collections from which fresh material could be studied. All this was studied in Malaya, the new species being sent to the Belgian Congo (P. H. V.-G.) for study together with the great wealth of material which was being collected there. Details are being prepared for publication. The present paper summarizes data on species already descriptionbed which can be correctly ascribed to Eutrombicula if this genus is regarded in a broader sense than hitherto.

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