Cytotaxonomic Characterization of the Genera Scleratoscopia and Tetanorhynchus (Orthoptera-Proscopiidae)

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In the present investigation we studied cytotaxonomically three species of grasshoppers of the family Proscopiidae, <I>Tetanorhynchus silvai, Scleratoscopia protopeirae</I> and <I>S. Spinosa</I>. Analysis of the phallic complex and of external morphological traits showed significant differences between species. In particular, comparative analysis of the phallic complex suggested that <I>Scleratoscopia silvai</I> Jago, 1989 should be reassigned to the genus <I>Tetanorhynchus</I>, as first described by Rehn (1957). <I>T. silvai, S. protopeirae</I> and <I>S. spinosa</I> have diploid numbers of 2n =19 X0 in males and 2n = 20 XX in females. The chromosomes of these species are described here for the first time. Although they present the same diploid number, these species differ in chromosome morphology. <I>T. silvai</I> showed a karyotype consisting solely of acrocentric chromosomes, whereas <I>S. protopeirae</I> and <I>S. spinosa</I> have karyotypes formed by two pairs of submetacentric autosomes and seven pairs of acrocentrics. In these two species, chromosome X is submetacentric. The karyotype of <I>Scleratoscopia</I> was considered to be derived due to the probable occurrence of pericentric inversions from an ancestral karyotypes consisting of acrocentrics. Three species analyzed are monomorphic for their karyotypic constituints. C-banding showed that these species have small blocks of constitutive heterochromatin in all chromosomes in the complement, except for pairs 7 and 8 and for chromosome X of <I>T. silvai</I>, which presented larger blocks. Silver nitrate staining in early prophase and in specrmatids showed the occurrence of at least two nucleoli for each species studied. <I>S. protopeirae</I> and <I>S. spinosa</I> represent the first species in the family Proscopiidae, with a karyotype of 2n =19 (_??_) in which biarmed chromosomes occur. The chromosomal differences between T. silvai and the Scleratoscopia species also support the reassignment of <I>S. silvai</I> to the genus <I>Tetanorhynchus</I>.



    CYTOLOGIA 61(2), 169-178, 1996-06 

    Japan Mendel Society, International Society of Cytology

References:  24

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