Meiotic study of hybrids in the genus Eulemur and taxonomic considerations.

A reproductive study was conducted on seven hybrids of Eulemur showing chromosomal multivalents involving at least four chromosomes at the pachytene stage. Three individuals were infertile hybrids and one presented a reduced spermatogenesis. In three out of these four hybrids, multivalents were associated with the sex bivalent in a large number of spermatocytes (23%). The relative importance of the reduction of fertility in males linked to chromosomal multivalent formation as well as the genetic background is discussed with regard to the use of cytogenetic data for systematics. Our findings argue for the classification of Eulemur fulvus collaris and E. f. albocollaris in two separate species. In regard to their repartition area, their separation along a linear north-south axis in Madagascar is discussed.