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Chromosomal multiformity in Botanochara bonariensis (Coleoptera, Chrysomelidae, Cassidinae)
C.E. StolarI; C.J. Bidau I,II
IFacultad de Ciencias Exactas, Químicas y Naturales, Universidad Nacional de Misiones, Félix de Azara 1552, (3300) Posadas, Misiones, Argentina. Send correspondence to C.E.S.
IICONICET (National Research Council).
ABSTRACT
The Cassidinae are characterized by highly conservative karyotypes, except in the Stolaini. This tribe shows the highest chromosome numbers in Coleoptera and complex chromosomal sex determination systems. We analyzed four natural populations of Botanochara bonariensis from Misiones and Entre Rios Provinces (Argentina). The Concepción del Uruguay sample showed 2n = 47 (male) and 2n = 48 (female), the male meioformula being 22 II + XpneoXneoyp. The Itacurubí population showed 2n = 27 (male) and 2n = 26 (female), with a male meioformula of 12 II + neoXpneoy yp. The Mbororé and Ñu Porá populations showed 2n = 41 (male) and 2n = 40 (female) (the chromosome number of both samples is the modal one due to the existence of Robertsonian polymorphisms) and the male meioformula is 19 II + neoXpneoy yp. Autosomal morphology also showed wide variation among samples. Our results suggest that chromosomal speciation has been a relevant mechanism in the evolution of the genus Botanochara, this process was probably favored by the small size of demes, low vagility and host plant specificity. A taxonomic revision of B. bonariensis is needed to clarify the status of this morphospecies, possibly an array of several sibling species.
Keywords: karyotypes; chromosome numbers; sex determination; Coleoptera.
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