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Experimental & Applied Acarology, 21 (1997) 629648Regeneration of Hallers sensory organ in the
tick, Ixodes rubicundus (Acari: Ixodidae)V.N. Belozerova*, D.J. Kokb and L.J. FouriebaBiological Research Institute, St Petersburg University, St Petersburg, Old Peterhof, 198904
RussiabUniversity of the Orange Free State, Bloemfontein, Republic of South Africa
(Received 28 August 1996; revised 26 January 1997; accepted 9 April 1997)ABSTRACTA study of regeneration in nymphs and adults of the South African tick Ixodes (Afrixodes)
rubicundus, from which the forelegs had been amputated during the previous instar, revealed that
the structural changes in regenerated Hallers sensory organs resemble those observed in other
ixodid ticks, in particular in another prostriate tick, Ixodes (Ixodes) ricinus.The adult regenerates
re-establish their atavistic features in terms of the increased number of different sensilla on the
distal knoll, in the anterior pit and the capsule. The nymphal regenerates, in contrast, re-establish
the features of the previous instar through a reduction in the number of some sensilla on the distal
knoll and in the post-capsular area. The structural changes in different compartments of the organ
appear independent. The phenomenon of regenerative induction through the appearance of
specific changes in Hallers organ of the contralateral non-treated foreleg is probably characteristic only of prostriate ticks. A unique modification in the regenerated Hallers organ as revealed
by duplication of the Hallers organ capsule was discovered in both I. rubicundus nymphs and
adult ticks.Keywords: Hallers organ, regeneration, sensilla, Ixodes rubicundus, ticks.INTRODUCTIONIxodid ticks possess a high ability for the reparative regeneration of body appendages (Rockett and Woodring, 1972; Belozerov, 1993) and of their sensory
equipment, particularly of complex sensory organs (the so-called Hallers organs)
situated on the tick forelegs (Leonovich and Belozerov, 1992, 1993; Belozerov and
Leonovich, 1995). After regeneration, these organs reveal some specific and regular
changes in their structure, in particular in the set of sensilla and their topography
(Leonovich and Belozerov, 1992, 1993; Belozerov and Leonovich, 1995). Some of
these regenerative structural changes could be interpreted as atavistic and the data* To whom correspondence should be addressed at: Tel: (812) 427-1009; Fax: (812) 427-7310;
e-mail: [email protected] 1997 Chapman & Hall630 V.N. BELOZEROV ET AL.on Hallers organ regeneration can be of help, therefore, in solving some of the
problems in tick phylogeny and taxonomy. The regularities of regenerative modifications...