Leggadas (Mus sp.) de Moundou (Tchad). Observation d'un caryotype aberrant chez une femelle

Pigmy mice (Mus sp.) from Moundou (Tchad), Aberrant karyotype in a female.In a sample of 12 pigmy-mice, one male had the karyotype 2n=36. N.F.=36, sex chromosomes PR, already known from five different taxa, but morphologically it does not belong to any of these. Ten specimens (7 , 3 ) present the karyotype previously described in a population from Ippy (Central African Republic) and for a male from Senegal: , 2n=19, sex chromosomes X/Y₁Y₂; , 2n=18, X/X. Probably we are dealing with a taxonomic entity derived from the superspecies minutoides/musculoides.An aberrant karyotype was found in one female: 2n=19, N.F.=37. The supernumerary is a small acrocentric, morphologically similar to the Y₂ of the male. Its origin could be explained through non-disjunction during the first moiotic division of a paternal spermatocyte, X and Y₃ having passed together to the same daughter cell. If Y₂ is homologous with a segment of the autosomal arm of the X/TR, the complement XXY₂ does not imply the intersexuality of its bearer, but should be considered as an autosomal duplication.