The largest known chromosome number for a mammal,in a South American desert rodent

Summary Tympanoctomys barrerae, a desert specialist member of the family Octodontidae, until now thought to be conservative, and ancestral to South American hystricognath rodents, presents the highest diploid chromosome number (2n=102) known in a mammal. Unexpectedly, its karyotype was found to be composed mainly of metacentric to sub-metacentric chromosomes. Mechanisms by which such a karyotype may have been derived are discussed.     

Karyological conservatism in South American camelids

Summary Llama, guanaco, vicuna and alpaca show similar diploid numbers, gross chromosomal morphology and homologous G, C and NOR banding patterns. This chromosomal homology is also found in the two-humped camel and very probably in the one-humped camel as well. These findings indicate that the camelid karyotype can probably be traced back to early Miocene times. This probably represents the most extreme case of chromosomal conservatism among mammals.This work was supported by grants from the Organization of American States and SECYT.Acknowledgments. We wish to thank Dr. M. Pizarro for his assistance and encouragement.     

Revision of the isopod crustacean genus Mothocya Costa,in Hope, 1851 (Cymothoidae: Flabellifera), parasitic on marine fishes

The genus Mothocya is fully revised. Irona Schioedte and Meinert is placed in synonymy with Mothocya. All named species but one, including 18 new species, are described and figured in detail. A further eight undescribed species are listed. With one exception Mothocya species are all gill parasites found principally on atherinomorph fishes of the families Hemiramphidae, Belonidae, and Atherinidae. Brief accounts are given of the biogeography, biology and host-parasite interaction of the species of Mothocya. Keys to the species are provided for the different major biogeographic regions.